mercury tohatsu 4 stroke 25hp 30hp outboard burning out ECU with aftermarket fuel pump

I added diodes to retain the battteryless feature of this motor..if I had to I could run it without the battery and both stators would power the pump.
you can just run the pump off the battery and charging circuit and use the pumps original power to trigger a relay, it's easier but you have to have battery power of course. without battery there is not enough amps to keep pump running at idle.

[@nicktr823]

Can you provide an amazon link to the diodes you used. Also, if i used a relay to power the pump directly from the battery, would i still need diodes?

[@omieyouknowme]

@@nicktr823 can search for 20SQ045 diode made by tnisesm. The relay is there to take the load and is a means to turn off the pump when engine turns off. Highly recommend you use a relay to run pump. It's a safety feature too you don't want pump running with motor off. The diodes are there so ECU is not starved of current. If motor is running the ECU will always have enough current to do it's work and excess is sent to pump. The pump will then draw the rest of the current from battery or elsewhere. If you don't have a regulator charger on manual start motor you can just run off a battery. Your battery size will limit how long you can run so if you use a 50ah lithium battery expect 8 hours then you charge battery again. If you tie the battery to fuel pump power as shown in my diagram with diodes you can double that run time. If you add a voltage regulator on battery side your run time now is based off fuel instead. I would recommend you use fuel pump wires from ECU to trigger a relay. Where the relay gets it's power is up to you.

[@adamviklund6574]

Great video! Having problems with my Mercury 25 from 2013 (just 40 hours on it), OR-serial with tilt and electric start. My engine died after 5-10 min on the water (it did start when the engine was cold). Authorized mechanic identified a bad high pressure fuel pump (and said it works until engine is warm). They said there were power to the pump and advised me to replace it. I installed an aftermarket pump and it worked great for 1-2 h - then the engine died and now it won't start at all. I connected the fuel pump directly to the battery and it starts right up. When I measure volt in the connector that connects to the VST it shows around 15 V - but the second I connect it to the VST it goes to 0 V. Therefore I figure my ECU is fried and I'm looking into your solution. The thing that bugs me: what was the original issue? Can the original pump fry the ECU? I connected the original pump to a battery and it still works - so I'm thinking the mechanic got it wrong and I replaced the original pump for no reason. BTW: the filter at the bottom of the original high pressure fuel pump was super clean.

[@omieyouknowme]

@@adamviklund6574 your symptoms are exactly same as mine. The high pressure filter was clean as well. My original pump was dead when I purchased the motor. The pump was seized, it had sand in the impellor. I would assume that trying to start the motor with pump bad pump had caused high enough resistance that I fried the negative driver in the ECU. I am not shocked how fragile this design is, would have used a fuse at min with original design to blow if pump has instructions and causing higher Amperage draw. Good luck to ya. I sold this motor and boat last year.

[@adamviklund6574]

@@omieyouknowme Thanks!!! Now that you mention it I saw some sand at the plastic thingey at the bottom on the original pump (where the filter sits) I bet there was sand in the impeller. Well then I think I have my answer. When I crank my engine I also (sometimes, it kinda comes and goes) get intermittent beeps and flashes on the engines warning light. According to the manual indicates ""Water temp or MAP sensor out of range". I assume the MAP sensor is reacting to the lack of fuel??

[@omieyouknowme]

@@adamviklund6574 map sensor measures elevation for the first split second then it measure vacuum inside intake. It's used to measure how much air goes in then ECU applies fuel based off map sensor throttle position to achieve best air fuel mix. Basically a carb but computer compensates.for elevation and temperature too. The two initial beeps are oil pressure I believe, because the motor is not turning enough to open that switch. It's set to 5psi only. You can prob disconnect that switch ground it or open it and crank to verify.

[@JorgeSalvadorLopez]

I dont know why Tohatsu Made these engines so complicated just for move a propeller.ecu damage every week.i Will return to carburator.an ECU from quick silver 1100 dollars.same part in Yamaha system 350 dollars. And Mercury AND Tohatsu hard to find.

[@omieyouknowme]

This ECU is not fixable. Same with all small engine ECU. If you know someone who is familiar with micro squirt you can build one for 350$. There is also speedunio option. These are small ECU you can program. If I find another 25-30 up tohatsu I will try this. But id be concerned if ECU keeps frying on the motor you have other issues.

[@PhilippeAuguste-pp8td]

Hi sir l from Mauritius, have same problem my Tohatsu 30hp the Ecu get damage. No spark on the s plug the engine does not start at all. In in fact have 2 outboard motor. Could you please give me a cost for the modification and a new ecu. Thanks for you reply.

[@omieyouknowme]

Hi I'm sorry to hear that. I do not repair ECU and the tohatsu ECU can not be repaired just replaced If you have no spark, then this is most likely a kill switch issue. Disconnect the brown wire for stop switch or lanard and try again. If that does not work I will find the specific test for the two crankshaft sensors if they fail the ECU will not spark either.

[@trevorcothran3273]

And just bypass that ECU for the fuel pump, would that work?

[@omieyouknowme]

@@trevorcothran3273 use the positive wire from ECU to trigger a relay to run pump. If motor shuts off it will open the relay and shut off pump. This is how it's done on all efi systems

[@shawnkeenan2576]

I wanted to point something out about this setup. So seeing that you are using the negative signal from the ecu, that means that this will only work with an ecu that is still working. If you started with an ecu that had failed, how would you have done this differently?

[@shawnkeenan2576]

I just saw your reply down below. Use a positive trigger instead.

[@omieyouknowme]

@@shawnkeenan2576 yes. The negative is usual what failed. If you supply pump with 12v from external battery and motor runs, your ECU is still ok. The positive trigger can still run the relay and still provide some amps as well to pump if you use a diode. If you just want to run pump off a battery then use the positive trigger for relay only and call it good.

[@RaajjeAnglers]

I have the same engine. i got 12 volts for injectors, fuel pump. but the problem is it does not spark. i have tested lanyard switch and stop switch. it does not have any issue. resistance in both side cps is in range. i don't know why it doesn't spark. will it be a problem with ecu?

[@omieyouknowme]

If there is voltage and ECU is not sparking disconnect the kill lanyard wire. Believe they are the brown ones. Check each wire for continuity with ground if one is shorted out. The injectors working and no spark tells me it's lanyard or ECU. I will lean on the simple stuff first.

[@RaajjeAnglers]

@@omieyouknowme even warning light is not turning on. i checked continuity on lanyard switch. there is no issue

[@RaajjeAnglers]

@@omieyouknowme a faulty sensor can cause this problem?

[@omieyouknowme]

@@RaajjeAnglers can you try cranking with kill switch engaged for few seconds then release the kill switch button. Like push starting a car with manual transmission. I have similar situation now on a Yamaha and this is how I start it. I had this same issue on a mercury few years turned out to be bad stator.

[@michaellawson-j5z]

why not just use the ecu to ground (power) a relay that switches 12v to the pump?

[@omieyouknowme]

@@michaellawson-j5z this is how it's normally done on cars trucks and larger outboards. For the smaller ones that can run without a battery, a capacitor is charged on the first pull to provide the 12v supply for everything. That same charge powers the ECU which in turn grounds internally for pump idle injectors ect. If you run these motors off a battery, yes you can just ground a relay, but most people buy the smaller motors to run battery less. My circuit still allows a battery less operation by taking excess amps from the charging circuit for pump.

[@trevorcothran3273]

if I buy a factory pump I should be ok

[@omieyouknowme]

@@trevorcothran3273 ya. But it's 600-700$ if it fries ECU you won't be on the hook hopefully

[@malcolmlund7938]

I just got a the replacement fuel pump from Quantum and wired it with the time delay from my battery lead - just like you did. So far works great! But, you made a key point - Quantum will sell a lower amperage pump if requested? If true, I could have requested that and swapped it for my orig pump, with no special wiring required. Am I correct?

[@omieyouknowme]

@@malcolmlund7938 their low amp pump is same as regular pump. I measured current at 40 psi.

[@malcolmlund7938]

How could someone find and get the low current pump? Do they have to request it from the vendor on Amazon, or does the vendor have it listed on Amazon separate from the high amp pump?

[@omieyouknowme]

@@malcolmlund7938 there is no low current pump on Amazon or eBay. It's all the same pump. Low current pump is OEM from marine dealers and they run 600$ and up

[@brettgatz5834]

Thanks

[@danielmid6022]

hi, great video! do you have the part number of the lower draw fuel pump? would you trust it to run off the ecu or would you still run it on a seperate relay? thank you!

[@omieyouknowme]

Well the low draw pump pulled the same amp. I would not trust these cheap pumps they come from the same factory. I feel safer running a relay as this is how fuel pumps are run in automotive world and the 40+ hp outboard all use a relay.

[@danielmid6022]

@@omieyouknowme sounds good thank you! I saw another video where he uses a time delay relay. Do u think that is necessary?

[@omieyouknowme]

@@danielmid6022 delay relay not needed, well with electric start at least. With pull start maybe.

[@JoshTalbert]

I have a 2014 30hp that I replaced the pump on. Ran for 2 years no problems or errors lights. thought I burned out the aftermarket pump but I am still getting 12-14 volts to the pump lead when I hit the starter. Do you think my ecu is fried? pump still doesn't seem to be running so maybe it just wont run under load. just curious if you got any voltage to you pump leads when your ecu was fried?

[@omieyouknowme]

You will get positive voltage at the pump lead but not negative if the ECU is fried. Verify by running the pump with external power source. The ECU just grounds the power, that's the failure not the positive side.

[@JoshTalbert]

@@omieyouknowme so just to verify you are saying the ECU controls the pump from the negative terminal. Definitely still getting 12-14v on my meter when I hit starter across the pump harness leads. I want to try and measure the current in series and see if it drops under load

[@omieyouknowme]

@@JoshTalbert yes it's a negative trigger. The positive is same and shared with coil and injectors and idle valve all on same line. Put your hand on ECU if it gets hot while running it's overloading that circuit and u are on borrower time. Other possible issue is pump is working to hard with high pressure filter plugged and drawing to much amps to keep up

[@everestinspections9088]

What you going to burn out next

[@omieyouknowme]

@@everestinspections9088 this is how majority of efi systems run fuel pumps. Should last longer than pump. Motor was sold with boat

[@PhilippeAuguste-pp8td]

Hi thanks for your answer, I swaped the 2 sensors, having same issew. Has mentioned early I have 2 tohatsu 30 hp. Do think if I replace the Ecu I will not have the same problem later . I expreance that before the Ecu get damage. From your experience do you have any idea how the Ecu get burn. Have replace the wiring harness also. Thanks..

[@omieyouknowme]

If ECU is failing you may have a bad ground or the pump, injector or coil is drawing more power than is provided by stator. One trick is to take the common hot wire, that runs the injectors and pump and run it via a battery. That is find the hot wire which is common for all these and tap it with +12v The ECU will drive the negative side to operate the injection and pump. This would tell you if ECU is bad or if there is an issue with one of the three pulling to much of a load and burned out ECU

[@omieyouknowme]

Crank position sensor Single wire test against ground 148-222 ohms resistance Double wire test against red/white against black wire should be 148-222 ohms resistance Ignition coil resistance.17-.23 resistance with primary wire against ground Check the black yellow cable it's kill switch make sure it's not grounded

[@omieyouknowme]

Blue wire on fuel pump is common hot. But if you do not have spark there is another issue

[@ayhankucukozer1478]

Tohatsu outboard does not get gasoline into the cylinders. The injector, ecu, spark plugs are intact. When I pour gasoline into the pistons, it works a little. When I press the starter, oily gasoline comes out of the exhaust. Could the high pressure pump have malfunctioned? How can I test it? Greetings from Istanbul, Turkey..

[@Aetius63]

Hi Omie, great video you produced, it's very orienting. I have a Mariner 25 HP Four Stroke EFI engine (OR201916 )), absolutely manual, my fuel pump burned out and once replaced (I did not resort to a Service Officia Mercury, I clarify), the shutdown was altered. The man overboard caused a short circuit and the engine wouldn't start. I live in Argentina and after your publication, I understand that no one knows exactly what are the characteristics of the relationship between the amperage of the pump and the ECU of this engine, so I can assume that the inconvenience that arose may be collateral damage of the replacement of the original pump with one that does not correspond to the model and year of this engine? I have already contacted Quantum and they have already suggested the exact model of them corresponding to my engine (HFP-382OB). Can the issue be reversed? Thank you very much for your contribution, Ezio.-

[@omieyouknowme]

Sorry to hear about the kill switch. Sadly once the fuel pump driver circuit is damaged it can not be repaired economically at least. I tried to remove the potting compound from the ECU with various chemicals and the time effort was not worth it. Be careful any pump other than an OEM pump even one from quantum could cause more damage. The cheaper aftermarket pumps, they do work fine on larger motors.

[@Aetius63]

@@omieyouknowme Thank you very much for your quick response. Do you think that changing the fuel pump mentioned above recommended by Quantum, could solve the problem of the shut-off switch? Or does the fuel pump have nothing to do with the kill switch?

[@omieyouknowme]

@@Aetius63 they are separate issues. If you can run the pump by applying 12v manually then crank the engine if still no start then there is something else going on. The kill switch is nothing more than grounding the brown wire. I would run a continuity check on the brown wire with kill switch in place. If you see ground on it with kill switch in place then there is a break in the wire somewhere to ground or switch itself is bad. The ECU rarely goes bad with the kill switch being grounded it's designed for that. Worst case trace the ground wire to ECU The brown wire goes to pin 3 this should not have ground unless kill cord is removed. Pin 28 on ECU is ground. This must be grounded at the lanyard with black yellow to brown or black to black on kill switch.

[@Aetius63]

@@omieyouknowme The pump since it was replaced, works well and the engine always started without problems, the problem is that the engine would not start with the man overboard device put on the switch. But thanks to your guidance, we will review the continuity of the cabes and their connections. Thank you so much for your support

[@omieyouknowme]

@@Aetius63 there are only three items that can cause a no spark no start. The kill switch, crank position sensors and stator. The crank position sensors if one fails will run but may not start. If stator fails it will not provide the need voltage to ignite the coils. Good luck. I often thought about adding a carburetor back into the block but this motor firing pattern is unique and needs sequential. Not possible sadly

[@amimer-enginezer]

GOOD MORNING I have the same engine recently I start for 15 minutes maximum, the engine turns off and it does not restart until it cools down knowing that there is no cooling problem.

[@omieyouknowme]

Run the fuel pump with external battery, does it stay running for more.thsn 16 min

[@joelflowers7500]

Hello. Thank you so much for your video. I’m about to take on the same project. I was curious about one of your comments. You said that any motor with the OR serial number was subject to this. My serial number starts with a OR but it’s a 2018 I’m wondering if that still applies if they changed everything in 2014?

[@omieyouknowme]

Interesting that your serial is OR. I would not think that later models are affected by the weak fuel pump driver in ECU.

[@JRDelirious]

I wanted to let you know that I replaced that pump. It works great! My issue with my motor wasn't immediately apparent. My fuel pump wouldn't throw an alarm until I ran it for a period of time, shut it down and then it wouldn't re-start. I kept thinking it can't be the pump. But after going through a whole list of things it might be, it ended up being the fuel pump that was the problem. Thanks for this video and I'm sure glad I found an answer to paying 600+ dollars for a 100 dollar part. I guess after it warms up it would fail. Who knows?? Thanks again.

[@omieyouknowme]

This is a symptom of your ECU overheating. When you are running engine put your hand on the ECU. If it's hot you are on borrowed time

[@JRDelirious]

@@omieyouknowme Oh man, that's not I wanted to hear. Even when I replaced the original pump? The ECU on my motor is way behind a bunch of wiring in the front of the engine 60hp Merc. EFI. It ran great when I installed the aftermarket pump from Quantum. Would it be possible for the original fuel pump to cause the ECU issue? It's only a 5 year old motor... Kind of sucks but, it's nice to know where I need to look next time I have problems though...

[@omieyouknowme]

@@JRDelirious the 60hp doe not have ECU issue it's only the smaller motors under 30hp. Aftermarket pump should be fine on 60hp

[@JRDelirious]

@@omieyouknowme Thanks! I've been thinking about that all day! Anyway you letting me know that the aftermarket fuel pumps work good was a big $$$ saver Thanks again!

[@omieyouknowme]

@@JRDelirious make sure you replace the low pressure and high pressure fuel pump after new pump goes in. Low pressure pump filter is the big round one hanging on port side. High pressure sits at bottom by spark plugs. It's encased in black foam' it is hard to get.to but easy to replace, push on red clips. Lots of videos on it

[@colinspinella2677]

Can you put like a 3 amp diode off the fuel pump wire that runs to the ecu.. my ecu fried from aftermarket fuel pump and was wondering if putting a diode on just the negative and positive coming off the plug on fuel pump going back to ecu will keep it from getting above the 3 amps

[@omieyouknowme]

No it would limit the pumps output and heat it up. I tried similar approach by driving pump with just stator putting out 2.5 amps burned up the pump. Pump needs full amperage from either battery or by joining two power sources.

[@tedroman7091]

I have a 2013 25hp with a similar problem. Runs great for and hour sometimes and shut down. Wait an hour or so and it starts right up. This been going on for years. Any help or suggestions would be great. Water pump was replaced. I'm trying to run it with the cover off. Or mount a fan under the cover blowing on the ECU

[@omieyouknowme]

Are you doing a lot of idling? Next time when it's been running for 20min put your hand on the ECU is it Hot! Checked fuel filters high and low pressure? A blocked high pressure filter will load up the pump, since it's that old it's best to replace it. Sits under the fuel cooler pita to get to it's sitting vertical metal canister. I used a napa filter was 8$ vs 45$ for outboard

[@MicheleBrugnerotto-lo3vo]

Good morning Im following you from italy and yout videos are very interesting. My 25 mercury efi is an 0R282938 . I have around 800 hours on it with the first pump. I have a battery Connected. Is better to make this modification? Or i need only to pay attention at the pump amps for a future? Thank a lot and sorry for my english.

[@omieyouknowme]

800 hours leave it alone. Replace the high pressure fuel filter and keep doing what you are. If you modify motor per how I did it, it balances the amp and retains the battery less feature of the motor. If you decide to run a relay with a battery that will work but your battery will not charge at idle unless you run it at 2500rpm or more you will drain battery

[@beekay6198]

What color was the trigger wire for 0R motor used in the video? I have the same motor, and can't find the +12vdc trigger wire in the remote umbilical, to trigger the relay's coil...

[@omieyouknowme]

The two wires for fuel pump one is positive which is common wire for all the 12v in motor, I don't recall as I'm not near motor. But you can trigger coil with negative if your ECU is still good. If ECU is fried use the positive trigger coil.

[@michalispapagrigoriou6192]

hi .ispossible to know what kind of Time delay relay use? thangs!!!!

[@omieyouknowme]

I don't know because I don't use time delay relays. Amazon may have one

[@cantinadiscus]

Hi ,I have this motor,I have this issue when turn key no status light and no beep , engine no start!! If I try to star more and more time I listen a beep and engine start!!! But ecu when I turn the key (first step) take energy from battery? Or only from stator when the flywheel starts to spin??

[@omieyouknowme]

There is no power to ECU with key in, only when the stator is turning over. It has to charge a capacitor inside ECU. But once it's running it starts all day, the capacitor will discharge over a day. So first start it can take two or three tries. Normal

[@Anne-ClaireBADIER]

Good morning, I had the same problem. Can we connect the fuel pump with the rectifier output and parallel the output of the electronic box in order to obtain the right intensity for the adaptable pump?

[@omieyouknowme]

That's what I did. I added a diode though on each line feeding the pump. If you have tilt trim and trim the motor it could draw amperage from the ECU side, the diode prevents this on main line. The diode on ECU line will help prevent a surge back into injectors and ECU as well

[@extreamsportsenthust]

Any more Info on this issue?

[@omieyouknowme]

Not sure what you are asking. I have almost 60 hours on motor after making this video and modification with aftermarket pump. U can see motor running in later video I posted on lake pend in Idaho

[@omieyouknowme]

kzbin.info/www/bejne/o3Oloat9nLGngtEfeature=shared

[@omieyouknowme]

Other issue I had was a piece of fuel line broke and was lodged in VST inlet. Blockage would starve the motor because needle was open but not enough fuel went to pump easy fix hard to troubleshoot

[@trevorcothran3273]

What would it hurt to hook the fuel pump to its own power source on a switch?

[@omieyouknowme]

@@trevorcothran3273 no. But if there is emergency you need to be able to kill it or fuel will keep pumping

[@John-p9z2y]

How would this work on a manual start

[@John-p9z2y]

​@@omieyouknowmehow will this work on manual starr

[@omieyouknowme]

@@John-p9z2y yes. But you have to install a voltage regulator first. Look on starboard side of motor for the three yellow wires. If present buy the voltage regulator and add it. Use the output from it to run pump and charge battery. The OEM are pretty expensive but aftermarket will work as well.

[@John-p9z2y]

​@omieyouknowme is that a adjustable time delay relay ?

[@willichenca]

Do you where I can find ECU for motor?thank you

[@omieyouknowme]

I bought mine from eBay, but boats.net has them as well.

[@FishingFun23]

You mentioned getting the high-pressure filter at Napa. Can you share the part number?

[@omieyouknowme]

Wix filter 33033 it's 1/2" longer but fits like the tohatsu in same holder

[@FishingFun23]

Thank You!@@omieyouknowme

[@AlejandroGonzalez-wh1vx]

hi, i have been looking at videos and internet about this problem , my pump gave out and want to replace it with a quantum pump i was going to do a relay so i wouldn't burn my ecu but i saw you comment that it only affects smaller engine size motors , i have a 2015 60hp efi outboard , so i should be good with just placing pump and not having to cut into harness to add a new relay for aftermarket fuel pump correct

[@omieyouknowme]

Thay is correct the 40hp and up are not affected.

[@dannyhvac37]

Hopefully not too late. I think I have your same engine 2015 60ELPT. Aftermarket pump fried my ecu 1st use. Dealing with repairs now. If I would have known then I would have just bought the OEM $600 pump. I could put a replay in now and bypass the ECU but the resale value would be killed, Looks like now I have to get the factory ecm and oem pump now. Let me know how yours turns out.

[@omieyouknowme]

@@dannyhvac37 the ECU on 40hp and up motors already use a relay. So this video not applicable to your situation Good news is your ECU can be repaired. There are online repair places that can do it n

[@extreamsportsenthust]

Would love a step by step on this for us electronically challenge folks!

[@omieyouknowme]

I drew it up on a paper. My version is bit more because I troll a lot and redid it how OEM would. For most everyone else though The basic thought is You run the pump off a relay The relay takes power from battery/alternator on one side and sends to pump. Other side of pump is ground to engine Relay is triggered using old fuel pump positive and negative wires. The ECU fuel driver circuit has no real load now

[@extreamsportsenthust]

I bought a Tohatsu pump for a 05-14 25-30hp for $450. I have 45 min of run time with no issues. ECU has not gotten more than 75 degrees. P/N: 3AC043100M Fuel Feed Pump

[@omieyouknowme]

@@extreamsportsenthust I spent 250$ on the entire motor. It was worth more as parts, but now that it runs, it's a pretty nice motor quiet and despite being heavier than the two cyl Yamaha version it runs smoother. Did end up costing me a new used ECU and throttle body but it's boat motor, hole we throw money into Hoping others find this useful as a lot of older motors out there.

[@simenfiskaa3608]

Hey! Thanks for the video! I have a mercury 30hp 2016 with serialnumber starting at 0R. The ground on my ecu is allready fried, after inserting an aftermarket fuel-pump. Any suggestions for what to do? Would it be possible to controll the supply from the battery with the relay, and controll the relay with the supply from the ecu and directly grounded. In addition to wire the ecu supply with the battery supply to drive the pump? Or would it be easier to just by the original fuelpump and using the positiv supply from the ecu and ground it directly?

[@omieyouknowme]

If it's already fried the negative trigger is what went out. Use the positive output from ECU to trigger a relay. Assuming this is electric start then either run the relay off the battery side or use my diagram and diodes. If you want to go OEM have at it but damage is done to ECU and they are getting harder to find new or used. I contemplated just converting to carb at one time, since low pressure pump and ignition is there just needed fuel.

[@simenfiskaa3608]

Thank you for answering, it helped a lot! I went for the after-market pump and diods and it got the engine running. One problem occurres when I restart the engine after running it, without relesing the fuel-pressure on the «measuring valve». Then it starts fine, but when I turn up the speed, it slowly shuts down. The same happens if I run the engine for a long time (60min+) without turing off and relesing the fule pressure. Any ide why? Could it be because the pump draws 4,5A (measured) and making too much pressure? I have not measured the pressure, but I will. Could a solution be an extra fuelpressure-regulator between the vapor-separator and the injection, if the fuel-pressure gets too high?

[@simenfiskaa3608]

I tried delaying the pump with a manual button, just to check if a time-relay was a solution. I tried between 1 and 10sek, but the same thing happens. Only differense is that it takes longer time before the engine starts shutting down.

[@omieyouknowme]

@@simenfiskaa3608 bypass the ECU to trigger the fuel pump relay. Meaning power the ECU from battery and try again. If it does not die your fuel pump circuit inside ECU is done. This would isolate it to either ECU issue or fuel issue. If the engine still dies running.it.off battery then you can look at vst needle seat where low pressure fuel comes in, measure low fuel pump out pressure should be 3psi give or take.

[@henrywiltz6008]

We’re are you located

[@omieyouknowme]

Colorado mostly

[@drewda610]

So I’m having the same problem with no power to fuel pump but only after the motor warms up. Added a new ground directly to fuel pump and still doesn’t want to hot start. 2014 25hp OR serial number. Is my ecu fried or possibly just getting too hot due to fuel pump pulling too much amperage? It is a stock pump I believe, bench tests fine. Thanks!

[@omieyouknowme]

Run the fuel pump trigger wires to relay, then have the relay pull from a battery to drive the pump. Make sure to have a flyback diode on the relay as well. Yah your ECU is probably done this will allow you to run it. With that said if you have a volt meter, check the amp draw in your pump with just battery. If pump is pulling to much is your high pressure filter plugged?

[@drewda610]

Filter looks fine, pump pulled .8 amps on a battery and 1.6 running under load in the motor. This seems pretty low, it was also with an Amazon multimeter so take that info with a grain of salt. I think I’m going to go the route of running it of if relay and replace pump if necessary. Do you have a part # for the relay with fly back diode you used or are they seperate parts? Thanks for all the info!

[@omieyouknowme]

@@drewda610 I used Ford relay from junk yard or you can find relays with flyback diode inside them. You can also add a small .50 amp diode in the terminals for fuel pump side.

[@omieyouknowme]

@@drewda610 how did you test under load? Run the negative to motor ground from pump, then run multi meter between pump and hit terminal in motor plug. The positive side runs the fuel pump injectors idle valve but it's the negative side that burns out it's the switch side

[@omieyouknowme]

@@drewda610 also check fuel pressure with motor running should be 43psi plus or minus 3. I used a tire gauge for this.

[@fern8808]

Thanks for the video, one of the few that actually helped and made sense. If your ECU is not yet fried then this is one method to go. Im about to replace my fuel pump on my 30 hp efi, I went over your diagram. I dont quite understand why you Teed the ECU power with the stator power? If you wire up the relay to use the ECU positive and negative on 85, 86 to trigger the relay and use the 30 to the stator/battery from the rectifier to run the pump positive lead on 87 and ground the other connector of the fuel pump to the motor. Wouldn't that be the same and there would be no need for the Tee connection from the ecu power, isolating that ECU from the fuel pump power? In theory if you have a dead battery in this method it would not fry anything but the fuel pump would not run as there is no power to the pump but, if you pull started it wouldnt the stator provide momentary power on each pull to power the ecu which would trigger the relay and draw power from the stator? Im no electrical engineer so if anyone could chime in. Thanks again for your video, i must have watched it 8 times lol

[@omieyouknowme]

The ECU and battery power side both have a diode on each line. They are T together because the main stator at idle does not put out enough amps to run the pump by itself. Same goes for the ECU by itself at idle it's only putting out 3.2 amps. If you power the pump from just the battery with a relay yes it's a simple circuit and this is how larger motors operate. But if you idle or troll a lot that battery will be powering the pump and you will be left in the water stranded if it's to low of a charge. So the solution is to power from both circuits. The positive and negative from ECU powers the relay which does not take any kind of a load. By feeding it to the pump as well it still works as primary source of power. The relay all it does is closes the ground from main motor to pump, this is actually taking the bulk of the load. Then the main stator delivers the additional 2 amps to the pump via the T. At idle this circuit works great, because both circuits put out 3 amps, I have 1 amp left over on main stator to charge battery and or run fish fish finder. Here is where the diodes come into play. As you increase the rpm the ECU will provide more amperage to the fuel pump. At the same time because the ECU is providing more amps the main stator for battery outputs more and will reduce it's output to pump and divert it to the battery. The diode also prevents the battery or tilt and trim from pulling amps from ECU. This way the ECU is protected as the amps is only going to the pump. I was able to measure the current flowing from each circuit on water and this little jack works passively.

[@omieyouknowme]

The ECU frying is on the negative sise trigger not the positive. By using the negative from main motor case the pump has all amps available from the ECU and the rest is supplemental from main stator

[@fern8808]

@@omieyouknowme - Thank You for the explination. It really helps. I just ordered parts to do this, ill use your method, funny im having trouble finding a relay with diodes on amazon, ordered a bosch relay with a diode on 85,86 but also ordered 20 amp diodes as per your diagram. Ordered a new low pressure fuel pump as the housing has some sort of corrosion making those clear discs not seal well. Using 14 gauge wire, will let you know if it works. Everyone should see this video before replacing their fuel pump with an aftermarket one.

[@omieyouknowme]

@@fern8808 the flyback diode on relay is to also protect the ECU from spikes when it turns off. You can buy relay at Napa as well. Be sure to check and replace high pressure fuel pump filter too. After this video I had a piece.of fuel line break off from low pressure inlet and plug the needle. Motor was starving for fuel at mid throttle.

[@fern8808]

@@omieyouknowme thanks, replaced all filters , plugs and low pressure fuel pump, cleaned injectors and in the process of replacing the high pressure pump. everything but the fuel lines replaced and the high pressure reg. I guess im the guy who thres parts at it lol got stun out on the water one season and was trying to get back using the trolling motor.. almost made it. a boater was nice enough to tow me to the dock after 2 hours of trolling back. This motor is noew to me, when i purchased it it ran fine, a year later it didnt run as it was sitting in my garage while i was raising the transom of my boat. when I fired it up it sputtered and thought it was the filters so I replaced them, same thing, thought it was the fuel pumps but read the after market ones fry ecus and came accross your video. Its the only one that explaines in detail what you need to do . Thanks again ill let you knwo if it works out, waiting on blade connectors lol

[@JRDelirious]

So, if I had a 1C serial number 60hp engine would the Quantum pump work? I really hate to buy that $600+ pump from Merc.

[@omieyouknowme]

The larger engines have bigger stators to push more amps and use a relay to drive the fuel pump vs the ECU direct. Should not be an issue using the quantum pump.

[@JRDelirious]

@@omieyouknowme Thanks, I've been on the fence with all I've read about aftermarket pumps. This video really helped.

[@omieyouknowme]

@@JRDelirious the pumps all come off same line for aftermarket weather you spend 20$ or 100$ same pump. The OEM usually have higher quality control but cost of one OEM I can buy 5 aftermarket. I keep one as spare in boat takes with tools takes.me 20 min to swap out. Pump will fail if they run dry from low pressure pump failure or debris getting jammed inside them. Pretty reliable otherwise regardless if OEM or not

[@JRDelirious]

@@omieyouknowme Thanks. Great research. A ton of things are like that, all the same factory just different brands...

[@dannyhvac37]

How did your repair go? I have the same 1C 60hp (2015), looks like the pump fried my ECU, just wondering if you did any better?

[@ScallywagSailing]

I have a 2013 MFS30B. Motor turns over fine. No spark on any spark plug. No warning beep when I first turn key on. Any ideas? Thanks!

[@omieyouknowme]

Start with kill switch if no ignition. It's the easiest and first thing that goes. Find the wires that go to kill switch one side is ground the other goes to motor. If you have a multimeter prob both wires with continuity test one side should beep the other side should not with key inside switch..if it beeps both sides a new switch. If it checks out good then look for 12v at Injector wire when cranking, if you get 12v there then it's waking up the ecu. Can go from there a few more tests can be done in the two crank position sensors.

[@ScallywagSailing]

Stator checks out good both ohms (.4 all three legs) and about 8 VAC when running all three legs. With starter turning the engine over, VST FFP plug has 12 VDC measured unplugged directly into a voltmeter. When I jump the VST FFP plug and supply ground and 12V directly, it pumps plenty of fuel. With the FFP plug inserted back into the VST and the motor turning over it does not pump at all. So this leads me to believe the ECU is not supplying the ground to close the circuit and activate the high pressure pump. Is the ECU waiting on a signal from any other sensors first, before supplying the ground for the high pressure pump...or is the ECU bad? AND, does this explain the no spark on any of the three plugs? like without fuel pressure the ECU will not provide the go ahead for spark?

[@omieyouknowme]

@@ScallywagSailing the ECU not supplying the ground for fuel pump is typical of the driver inside it burning out. This is pretty common and u can supply ground to the other pin and rig up a switch to go around this. Assuming the ECU is not getting ground on the kill switch, it would start. You said you are not getting spark either, this leads me to believe your ECU is either not getting enough voltage to start up from the stator, (6 white wires starboiside) or the kill switch wire is shorted to ground. Is this electric start? Tiller or remote?

[@omieyouknowme]

@@ScallywagSailing ECU does not sense fuel pressure, once it's turning over 250rpm it will generate spark and fuel. I'll dig up the stator testing this morning. I'm leaning towards the kill switch being grounded myself from what you described because ECU usually only has issues with over voltage or under. Also check the ground, there a small ground wire that attaches from ECU to block next to starter solenoid up front, in a round eleyet.

[@omieyouknowme]

@@ScallywagSailing brown wire from ECU pin 3 , if it test to ensure it is not ground. There is another brown wire in front harness, should be plugged if remote same test. Black yellow is lanyard stop switch that closes the brown wire from handle or lanyard

[@matssundin15]

I have a 2011 25HP non tiller ECM still good I just got this fuel pump what’s the easiest solution to keep my ECM safe

[@omieyouknowme]

If it's non tiller then you have electric start. I would do a dual power source like I did use a decent diode on each line to prevent feedback. Then use the negative for fuel pump to trigger a relay. The relay should close the negative side of pump to engine ground. The duel feed will allow ECU and main stator to feed pump all the amps it needs. As engine rom goes up the ECU provides the amperage. The negative trigger from ECU is what fails if you use that to drive a relay there is no load on that circuit

[@matssundin15]

Ok it seems so complicated I don’t even know where to start is the relay only for the negative and am I cutting the negative feed to the ECM completely?

[@matssundin15]

@@omieyouknowme ok with some research and after watching TJay P video I’ve decided to use the Beuler time delay relay. It seems to be the same principle but he’s installing it using an ECU with bad ground (bypassing it). Are you making your T connection in the relay? Seems in his video he’s done pretty much same thing except using positive to trigger the relay? Just wondering best way to use that relay with a good ECU and keep it protected. Send trigger to ground side instead?

[@omieyouknowme]

@@matssundin15 I don't know why he is using a time delay relay, his setup will also drain the battery at idle. He is using positive to trigger relay because that ECU is fried. If the ECU is still good negative should be used . I'm general fuel pump, injectors idle valve all devices are triggered from negative side. The positive side remains common. If you tone the positive wire on pump it will be same in injectors. This is how efi ECU work.even the fuel pump in your car is triggered by negative signal

[@omieyouknowme]

@@matssundin15 remember its KZbin and videos are suggestions or tips if you not comfortable take it to shop let them take responsibility.