Yamaha Outboard Won't Start Fuel Pump Failure Stalling

[@عزالخوي-ه7ظ]

Although the videos are few, they contain a lot of useful information that is difficult to find on another channel. All thanks and appreciation

[@stevenk7486]

FINALLY! I found the RIGHT video. Thank you Sir!! You rock

[@stevepaul2262]

What a great video. He even shows the oil change.

[@manbearpig8691]

Awesome video. I hit thumbs up & subscribed. I didn't have that much gas in my oil, but I did have some. Mine is a 2005 150 HP 4 stroke Yamaha. I'm 90% sure that you have found my problem! Wow that lift pump is over $200+ ! It needs to get about zero degrees before I can find out for sure.

[@Salli66]

Terrific Video , costly incident if not caught immediately,would also check plugs,especially if it ran with watered down fuel,Diesels are also known for that.

[@outboardst.comoutboardspec8631]

Thanks for your input, and couldn't agree more

[@alancall5113]

Is wow best on KZbinMan did you really help me Thanks for sharing big time

[@robertjackson7590]

Ethanol has caused so many problems with outboard it's terrible. I'm getting my 250 HPDI on my old boat project and just running a Holley Blue Marine with a regulator to eliminate all these problems. Installing a Racor 2 micron primary, pull the diaphragm pumps and block plates on the ports in the block. Good Luck....

[@brianaustin82]

Fantastic video. Bravo Zulu!!! Thanks -Chief

[@outboardst.comoutboardspec8631]

All good, hope we were able to help, thanks!

[@VEEZY_FISHING]

Can a bad pump cause a rough idle? I’ve changed my 04 F115’s injectors, cleaned out the VST, new spark plugs, and fuel filters and it’s still idling pretty rough

[@Thecoachco]

I have an issue with my 1999 Suzuki df 70 ,starts up ,runs rough with throttle lever up,stalls when lever put down,plugs fouled black dry carbon,bulb only sometimes gets tight,but mostly fills like somethings leaking ,changed plugs runs decent,,3 things I think it could be either Ignition coils,old rusted injectors and rail and the pump your talking about.,Maybe change all three?Please let me know your thoughts

[@Thecoachco]

When I get home,Im going to test my fuel pump,,thanks for the info

[@Thecoachco]

I tested my fuel pump and no leaks

[@outboardst.comoutboardspec8631]

Hi, so with 4 Stroke EFI fuel systems, there is a low pressure fuel pump, which is the subject of this video. The low pressure pump pulls fuel from the tank and pushes it into the Vapor Separator Tank, where another pump takes over and feeds pressurized fuel to the injector rail and injectors in volumes that vary depending on the demand from the ECU. Fuel pressure at the rail will always need to be in the range of 40 PSI. Too much or too little pressure and the motor will not run correctly. It is very common for EFI fuel systems to accumulate contamination and or water in the VST, and injectors over time and when there is enough debris it can cause fuel obstructions in the high pressure fuel pump intake, as well as the high pressure filter located between the VST and the injector rail. Also the injectors themselves can develop obstructions from debris which will cause them to malfunction. If the injectors and VST/pump have never been cleaned and filtration replaced on a 24 year old EFI motor, it is definitely something to inspect. An easy way to do this is to measure fuel pressure at the injector rail while the motor is running, you should always be in the 40 PSI range at all rpms for most port injected EFI systems. A good fuel pressure reading will not tell you if you have contamination in the injector rail, which is common, but a bad (low) pressure reading tells you that either the VST pump is failing or it is obstructed or both. A low fuel pressure reading is cause to go into the VST and inspect/clean and usually replace the fuel pump and intake filter. In addition to cleaning and replacing damaged parts in the VST, I normally replace the high pressure fuel filter, flush the fuel hoses and rail and remove the injectors and send them to a professional cleaning service for testing and cleaning. In your situation, the fouled plugs can be caused by the fuel injectors leaking, and hanging open, which will dump too much fuel into the mix and cause the motor to run way too rich, which will also cause the motor to run very poorly if it runs at all. These issues are common with a contaminated fuel system.

[@regkershaw]

I have the fuel issue with my F70. It will run fine for a while then when you put a load on it it plays up then stops. I've replaced the filter and the primer and fuel line ends and also fuel pick-up and gauge in the tank and it still has this problem. I was thinking it could be the pump but which one low or high pressure. I might have to change the low pressure one because it seems you had the same problem. Would you know the part number for that pump. I think its about a 2013- efi f70

[@outboardst.comoutboardspec8631]

The description of your problem sounds more like an obstruction or pump failure on the high pressure side in the vapor separator tank which feeds the injector rail. If there is debris or water in the high pressure side between the VST pump intake and the injectors, it will cause exactly the issue you are having. Normally the if the low pressure pump is failing, the engine will completely stall out until the motor is primed again by hand with the prime bulb. If the Injector pump is starting to fail or is obstructed, it will cause a drop in fuel pressure when the motor is at higher rpms and consuming maximum fuel volume. When accelerating, the fuel pump can't keep up so the engine drops rpms, but when the rpms drop along with the need for immediate max volume of fuel, the pump is able to catch back up. So, a very common symptom of VST pump failure or obstructed fuel injectors or both, is that the motor falls on its face during rapid acceleration or it may reach high rpms and then bog down, but when it falls off, it usually won't completely stall. Sorry for the late reply, are you still dealing with this issue?

[@dalegould8411]

Great video and information 👍🏻👍🏻

[@outboardst.comoutboardspec8631]

Thanks 👍

[@r.t.1942]

i have a 4 stroke yamaha fuel injected it lost power and would only idle , and would die and restart , do you think that could be the same issue on mine . yahama f150xtr. im new to boating

[@outboardst.comoutboardspec8631]

Hi R.T., sorry for the late response. It is a high probability that you are dealing with a fuel restriction of some kind. The pump that failed in this video was the lift pump which pulls fuel from the tank and pushes it into the Vapor Separator Tank. The lift pump on the F150 is identical to the model featured in this video, only with the F150 there are two lift pumps stacked together. Lift pump failure can be diagnosed by waiting on the motor to stall, then pumping the primer bulb to refill the VST. If you have to repeatedly refill the VST using the primer bulb or else the motor stalls, then usually the lift pump is to blame. Also check your oil, if it smells of gasoline, this is another sign that the lift pump is damaged and leaking into the crank case via the valve train. The other benefit of checking the primer bulb is that if there is an obstruction between the fuel pick-up and the primer bulb, you'll find it pretty fast since usually the primer bulb will go flat if it is obstructed. The high pressure pump inside the VST is responsible for feeding pressurized fuel to the injector rails and injectors. These pumps can also fail, with the early failure symptoms being that the motor will usually idle ok and run ok at low RPM's , often it will run fine on the hose, but under a load in the water, the motor will bog down when you go to wide open throttle/high RPM's. This test is a bit more complicated, but is still fairly simple: put a fuel pressure test gauge on the Schrader fitting on the fuel rail and test in open water. Fuel pressure should always hold steady slightly above 40 PSI. If pressure is normal at idle and falls on its face when you try to turn up RPMS's, you will lose RPM's and either drop down to idle/low RPMS involuntarily or stall completely. Either way, if this scenario plays out, you either have a failing VST/High Pressure Pump or the pump is obstructed or both.

[@gordonbrinker]

Could this issue occur on a 2006 250 Yamaha? Engine was running fine from launch to slip. Then a few days later it started right up and idled us out of the marina with no issues. Once in open water the engine kept bogging down and dying when throttle was given and rpm reached 1500ish. This happened about 4 or 5 times and then the engine would not start again. Wouldn’t even turn over. Just a click sound as if the starter engaged but couldn’t turn the engine over. We limped back in with the kicker and await word now from mechanic.

[@nothing_but_lunkers1584]

Should I be able to see oil inside when I take this pump off?

[@outboardst.comoutboardspec8631]

The back side of the pump is cam driven and is directly exposed to motor oil being pumped through the valve train, so yes. Pretty typical for the back/interior side to be oily.

[@UpperBayBassin]

Is that the 5qt or 10qt oil jug?

[@outboardst.comoutboardspec8631]

5qt

[@tonyjordan1320]

Great video, my 115hp Yamaha is not giving me any running problems but it is a 2004 model, should I replace this lift pump as prevenative maint.???

[@outboardst.comoutboardspec8631]

The lift pump/O-ring is one of the easiest parts to replace and not terribly expensive. It is a rare failure, but that said, when it fails, oil diluted with gas can cause severe damage inside the crank case. On an '04, probably a good idea.

[@irasaposnik6511]

I’d get an Eska my man

[@johnvillagomez637]

I have 1995 yamaha 150hp 4 stroke. Can that parts fit on my engine . My original pump is only showing ( MIKUNI MADE IN JAPAN 63P ) and nothing else.

[@thefishingchef3589]

So I have been having a hell of a time trying to figure out why my primer bulb looses prime. I’ve replaced everything. Lines, separators, etc, can’t smell gas anywhere from any fitting on the poly tank. But when it’s hot outside it will loose prime. In the morning when it’s cool it will hold fuel. Is there one way valves in these pumps that could fail? I have the same engine. Help!!!

[@PedroRodriguez-ui6pq]

excellent video , can you please explain how to replace just the diaphragm (40 $) the entire pump is 200 plus...thank you

[@FlexZero]

if i remove that pump without draining oil, will oil come out?

[@outboardst.comoutboardspec8631]

Not if the motor has been sitting for a day or a few hours. All (most) oil should have drained out of the valve train shortly after shut down. If it's jacked up like this one was, all bets are off. Removed about 5 gallons of fuel with some oil in it.

[@outboardst.comoutboardspec8631]

And if you suspect fuel has contaminated the oil pan, definitely time for oil change and oil filter

[@FlexZero]

@@outboardst.comoutboardspec8631The RPMS in my 90HP Yamaha motor haven't been able to get over 4200 RPMs. Sometimes it surges over that but only for a second or two. I did some research and seen Yamaha recommends changing this pump every 3 years. Do you think the pump could be my problem? I pulled the dipstick and gas didn't come out like it did in the video.

[@sparkyobrian6417]

Minor over flow" LMAO, fantastic video, as always !

[@kdiddy1310]

I have a 115 yamaha 4 stroke that runs for bout 10 minutes down the lake and then all of a sudden it dies and I have to pump the bubble to get it to crank. I pulled the lift pump and it wasn't leaking behind it, can it still be this lift pump as the problem or do I need to look somewhere else? Thanks and great video.

[@outboardst.comoutboardspec8631]

This sounds like a lift pump failure all day long. Can also be caused by other issues with the the boat fuel system (tank, pickup, hose, primer, filtration). If primer bulb is flattening out while your motor is running, this would indicate possible obstruction between the tank and the motor, or if primer is bone dry when you go to re-prime after the motor stalls, this could indicate an issue with the boat-side fuel system. Would inspect fuel hoses, primer, filtration for signs of leakage, smell of raw fuel anywhere besides near the tank vent is a red flag. If there is even a pinhole size air leak in the supply hose, the vacuum from the lift pump will just pull air, and stall the motor. Once boat fuel supply is ruled out we're back to the lift pump. On the inline 4 stroke Yamaha's the cam driven lift pump is relatively inexpensive (as compared to the 12V lift pumps on the V6 models). I would be inclined to just replace the lift pump and O-ring as a matter of preventive maintenance, especially if the motor is more than about 10-15 years old. While you are at it, inspect the internal fuel hoses going into and out of the primary (little filter on the port side of the motor), into and out of the lift pump. These are preformed hoses that are prone to cracking and dry rot and also need to be replaced after about 15 years.

[@kdiddy1310]

@@outboardst.comoutboardspec8631 ok, thanks for the advice. I replaced all the fuel line,filters,low lift pump, bubble. The bubble isn't pulling flat on mine. Even the inline and canister fuel filter and hose under the cover. Still having same problems. Is there anything else this could be? Mine will run up the lake fine when first put in the water. Then after about 15 min. It starts acting up. Try to get on plane and kapoot it falls on its face and cuts off. I can pump the bubble and it will crank back but runs for a min. Then cuts back off. I ohmed out the coils. They seem to be fine. Not sure what's left other than a computer. Thoughts? Thanks in advance

[@jamesmcguire1523]

@@kdiddy1310 the same problem I am having. what was the cause of it. would love to know

[@williamharding124]

@@kdiddy1310 did you ever figure this out, my 200 is doing the exact same thing

[@kdiddy1310]

@@williamharding124 nope still troubleshooting

[@mattjamesofc]

thanks for this video man, such a niche issue

[@apackwestbound5946]

Tyler forgive me if this is a STUPID question; isn't all that gasoline running around pressurized inside the crankcase a significant explosion & fire hazard? At this point, short of a complete engine tear down to measure internal tolerances, could you determine whether or not the gasoline diluted oil and that oil's compromised lubricating ability has already lead to significant damage to the internal crankshaft, camshaft bearings and/or journals? The "test run" on the river may go ok today and the engine could still prematurely fail catastrophically due to the damage caused by the failure of the lift pump. If you, the seasoned experienced professional in the marine technology industry that you are, were looking at a used boat/motor could you determine if this engine has a normal life expectancy ahead of it or if it is a "time bomb" about to expire? -Respectfully,

[@outboardst.comoutboardspec8631]

All awesome questions. Yes, I would think there definitely has to be elevated risk of fire or explosion from fuel sloshing around in a hot crank case. Possibly keeping the fuel under pressure in the oiling system has some effect in preventing it from lighting up? I have no clue. With fuel related topics I keep it simple, fuel, and fuel vapor, is designed to explode, and given the right conditions, fuel will always explode. Why it does not tend to explode or flash in these conditions is above my pay grade. When this situation came to my attention, I spoke with my old shop foreman and another tech I worked with back in the dealership days, and they said the same thing: seen this failure a few times, nothing ever blew up. Viscosity breakdown and related metal failures: Again, I'm relying on my fellow engine tech's who have seen more of these failures than I have. After strongly recommending that I advise the owner to part ways with this motor ASAP in what ever way allows him to sleep at night, which I did, they both said they'd seen a few like this and about half of them either showed up in the shop DOA with serious mechanical damage, with damaged bearings etc everywhere, or only lasted a few hours after delivery before they developed catastrophic mechanical issues, again smoked bearings mostly, and power head requiring complete tear down. In this case, the motor had an odd sound coming from the crank case that I've never heard before, but ran perfect in delivery/sea trial. The owner uses the boat regularly and has put another 50 hours or so on it since and has reported no problems yet. Signs of impending doom: Short of a crank case tear down, tough to say. This motor had 200 psi compression +/- when I checked it (hot with new motor oil). After compression and leak down, I can't think of much else. When I am doing pre purchase inspections for prospective buyers, the first thing I look at is motor oil. If there was heavy wear, one might luck out and find some shavings or "powdered steel"/excessively gritty feel in the oil samples, which would indicate serious failure. With bigger motors such as v6 with variable cam shaft timing, I usually check the filter screens in the stepper motors which adjust the timing on each bank. All of the motor oil in the motor passes through those screens, and sometimes they catch stuff that hasn't been fed through the oil filter yet. One might luck out and find torn up metal there. Other than that, there are not many easy ways to check for latent internal damage that hasnt killed the block yet.

[@MEGA_SOKO]

Gasoline in liquid form will not explode. Flammable and combustible liquids themselves do not burn. It is the mixture of their vapors and oxygen that makes it highly flammable. This is why a semi-clogged fuel injector can greatly hinder the performance of an engine, it needs the fuel to spray in an atomized state for the best burn. That being said, gas in the crankcase will not cause a fire because it's still in liquid form, add the fact that it was diluted with the crankcase oil. Hope this helps.....

[@tonyjordan1320]

@@outboardst.comoutboardspec8631 The owner has put another 50 hrs. on this motor and no problems? Somebody is living right.....

[@45mjv]

Thank you for the video. My lift pump fails on my 2004 F200 when the motor is very hot (i.e. after the motor has been sitting for 15 minutes in the sun on a 95 degree day after having been run). I then need to pump the bulb and run it until it stalls, 2 or 3 times, to get cooler air under the cowling etc. It then runs fine. Can anyone tell me how to locate the lift pump relay? Perhaps that relay is going bad and does not work when it gets very hot.

[@richarddarrah9368]

Hey mate I got a Yamaha f100 fuel injected and it’s hard to start on cold really hard takes ages of priming and winding to get it started, once it’s started it’s fine all day while fishing stopping starting etc

[@outboardst.comoutboardspec8631]

Richard sorry for the extremely late reply. F100 EFI is a rare bird. This issue sounds more like fuel injectors either obstructed or otherwise contaminated and leaning out the fuel side of the fuel/air mixture at cold start, when fuel should run rich. Once the motor is at running temp, it can and will run leaner. If this was a carbureted F100 I would say the same thing except the carburetors would be responsible instead of the injectors. There can be electrical issues that can cause similar problems, but they are less common that fuel system/fuel delivery malfunction. The number one running problem we see in our shop is fuel contamination and contamination related fuel system failures.

[@jarrodlynch9330]

Could this happen with a 2 stroke 50 hp Yamaha

[@outboardst.comoutboardspec8631]

Yes, lift pump failure can and does happen on any outboard, not as often on bigger v6's with electric lift pumps. If motor is running ok, then stalls and won't light back up until you hand prime the carbs with the primer bulb, odds are good there is a problem with the lift pump. Only difference between your 50 2 stroke and this motor would be that with 2 stroke you wouldnt get the oiling system loaded up with fuel since most Yamaha 2 strokes have either external or remote oil reservoir and anything hanging around in the crank case is getting sucked right into the cylinders to burn

[@ezrawilliams6280]

Another great video, thanks!

[@outboardst.comoutboardspec8631]

Many thanks. Tryin to post more footage of some of the random stuff I run into.

[@watercool5]

So this fuel pump was designed to pour gasoline into the crank case when it failed? I guess it prevents fires and fuel spillage, but at the cost of catastrophic failure. Ouch.

[@outboardst.comoutboardspec8631]

I often wonder whether or not they actually thought about what a component failure would look like during the design and testing phase way back in the day. Overall a pretty low failure rate for the cam driven pump, but yes, this pump failure can and does annihilate a crank case from time to time

[@kingdavid2684]

You are awesome sir.

[@smalldog221]

while you were doing that you should have replaced the filter between that failed pump and the vst.. that one caught all the debre from the failed pump and if clogged you wont get WOT.

[@outboardst.comoutboardspec8631]

Good catch and recommendation! Definitely inline filter replacement would be a strong recommendation with fuel system repair.

[@mhr7962]

Great video learned a lot

[@MM-zb1uj]

Good sound-not as a Evinrude sounds like a load of metal loaded of a truck!!!!

[@leea.6101]

It’s a 4 stroke... why extract the oil? Let it drain out. This way you know you’re getting all the contaminated oil out.

[@outboardst.comoutboardspec8631]

Hi Lee, in a perfect world (automotive??) I'd drain the oil out via the oil pan drain. However, through years of experience gained and money lost, I have learned some lessons regarding 4 stroke outboard oil pans in the saltwater environment: Mother Nature always wins, ALWAYS. Refusal to heed this fact gets pricy and fast. The combination of aluminum drain pan, steel drain screw, mystery metal crush washer and a roughly 10 year soak in saltwater (with apparently minimal post run flush in this case) is an ideal setting for galvanic corrosion and or electrolysis. A tech simply hasn't lived until they've accidentally stripped the soft aluminum threads out of a customer's oil pan drain, destroying it in the process, by extracting a drain screw that has been fused into the pan by corrosion. In a few seconds, a tech can sign up for extra hours of tear down at greatly reduced or no pay at all, so that the engine can be completely scattered and the oil pan can be replaced. In the blink of an eye, a nice juicy, profitable oil change can become a net loss/cash furnace, and a mechanic's bay down for at least one or two days, and that's if the engine comes apart peacefully. My shop foreman spit his coffee out and nearly fainted the first, and only, time I ever backed out an oil drain screw in his shop. This failure is rare, but it only needs to happen once to drive that lesson home. So, yes, and especially in a time crunch on a boat I've never seen, I always extract oil via dip stick port with a vacuum pump. Also, as you no doubt saw in this case, when I pulled the dipstick to check the oil, the contents of the oil pan weren't exactly waiting around for a drain. The video footage only shows the second time I pulled the dip stick, the first time I pulled it, not captured on tape, my shirt instantly became hazmat.

[@mikedobranski4711]

Thankyou

[@Boat_FishingDoduJeju]

good job.

[@irasaposnik6511]

This is just nonsense. These motors are just garbage