2015 Yamaha 115 4-stroke misfire diagnostics

[@johndouglas6079]

I just want to thank you for this video. My Yamaha 115 was doing the same thing-just out of the blue started missing. I went through the diagnostic process you laid out and was able to isolate the problem to spark plug on #3. I put in a new set of plugs, problem solved. Thank you again!!!!!

[@hotheadzmarine]

They are bad about spark plugs that's for sure.. Glad it helped You, Thank you and God Bless.

[@billarenz2719]

Thanks for the great trouble shooting video, you helped me get my motor back to running on all for cylinders. I started disconnecting injectors and found when #1 injector was disconnected there was no drop in engine rpm- switched spark plug made no difference, replaced injector- fixed rough running motor. Thanks again.

[@hotheadzmarine]

Awsome..Maybe you would be so kind as to leave us a 5 STAR Google review... it's super simple, fast & easy. It truly helps a lot and let's good folks know we're here to help ..g.page/hot-headz-marine/review Thank you so much again and God bless you 🙏

[@richardhohenberger2072]

I was informed by owners manual and You Tube? that you should not run a Yamaha F115 4 stroke when using the "Hose Flush Adapter " on the engine because the water pump rubber blade will over heat and melt due to not intake water from the Lower Unit slots on the engine!!!! (where the hose Muffs are placed!) The impeller does not get any water and runs dry!!! The upper hose connection only flushes out the top end of the engine!!! Therefore you probably just made the rubber water pump impeller worse............ Please correct me if I am wrong! Richard H. My engine is a 2015 Yamaha F115 4 stroke.

[@igotmesothelioma]

You're right

[@hotheadzmarine]

Read the comments, we're well aware but Thank you Very Much

[@RR-ph6zy]

I used to work at the Fukuroi City plant in Japan installing lower units, when using the hose port on the motor the water does fill the head, and naturally gravity takes its course and water runs down and out of the port holes in the lower unit, I'd say fine to run the motor with the hose in that port as long you let the water run long enough to run out of the lower unit before starting. All manufacturers put writing in manuals to protect the manufacturer against failures for warranty reasons.

[@chunkyfather29]

False ! You can run engine using flush port ! And I recommend it. First the powerhead gets water first and fills up. Preventing heat damage. Secondly, water runs down intake pipe into water pump housing lubricating it better then ear muffs. You can only run engine on idle or in low rpm in gear

[@richardhohenberger2072]

Let me ask this. When you engine is running isn't it designed for the water pump to push water upwards to the head? In that case it would be sucking air from the bottom end at the intake ports and into the water pump impeller. Just my Opinion. Richard

[@arielmesa100]

Great video and very very helpful for people like my self that like to know my engine in and out and most of the time is really really hard to find a honest outboard mechanic that would be straight forward and would try to save some dollars for the costumers, thanks for the videos keep up the good work!!!!!

[@kimseymour8896]

That a great video thanks for going through it so thoroughly.

[@donroyer420]

Good job of methodically troubleshooting!

[@hotheadzmarine]

God bless you Sir.

[@sapper3082]

THank you! I was having the same issue with mine and I am going to try this now!

[@beby138]

great video thanks for sharing

[@robertjackson7590]

Excellent video... Ethanol is a problems for any diaphragm pump that sits up. Phase Separation of the fuel.

[@hotheadzmarine]

Yes Sir.

[@peteraivaliotelis3219]

very nice and helpfull viceo. thanks guys.

[@hotheadzmarine]

Peter Aivaliotelis, Thank you for your kind words. God Bless

[@bryanleibe2298]

My 70 hp had the same problem with the sparks plug, two of then bad. Checked for spark and all fired but mechanic said I had two bad spark plugs on a engine with only 70 hours. Keep 4 new spark plugs in the boat now. Boat ran great for first 10 min. , stopped to fish and when I started again it ran horrible and had to limp back to the dock.

[@hotheadzmarine]

Overheating maybe?

[@jaywaldrop5236]

Got a 07 115 but it only “bogs” almost as its missing when it’s trying to get on plane. It never misses in idle or after up on plane. So not sure how to go about it. Changed all plugs still doing it. Do you have an idea of what it might be or how to test. Thank you

[@hotheadzmarine]

Thinking high and low pressure fuel filters, fuel line, spark plugs ect. Is it overheating possibly? Water impeller service? water in fuel? these are where we would start after confirmation of compression and spark.

[@jaywaldrop5236]

Changed the spark plugs went and ran it still doing it. Don’t think it’s over heating because it does it the 1st time you launch it. Changed the plugs. Only does it when trying to get on plane.

[@joshuapeters8435]

Just a question.If your using the hose flush, isn’t it bypassing the lower unit.Putting water straight into the head??

[@hotheadzmarine]

If you have one, hook the hose up to the flush..turn the water in..do you see water coming out of the water inlet ports? If so you are keeping the impeller wet and lubricated enough to idle for a short time without damaging it.

[@bluenoserterris5753]

Yes, but you cost the guy an impeller replacement he didn't need! No wonder people don't trust dealers....

[@emilyduron3004]

Emily Duron 15 minutes ago I have a motor that I think is ok but wanted to let you listen to it and see what you thought. It idles and a little shaky, but give it just a little Throttle and all is good. Only when prop is engaged. Is there a way to get a hold of you?

[@hotheadzmarine]

Email [e-mail]

[@emilyduron3004]

Thanks for all your expertise and getting back to me on my questions. Highly recommend to others looking for service .

[@sethsanner8586]

@@hotheadzmarine so I have a 2007 Yamaha f115tlr and it sat for a while so I changed ALL of the fuel filters on the motor including the one inside the vst and new injectors and it gets on plane and will only run about 4k rpm and slowly drops and will come down off of plain but won’t die, so I found fuel in my oil and changed the low pressure pump, and still have the same issue. If I stop and kill it and cycle the fuel pump, it will run 6,200rpm and then slowly drop rpm

[@hotheadzmarine]

@@sethsanner8586 Fuel in the oil would be the VST tank overfilling and venting into the crankcase.

[@charliesmith9528]

I have a 2017 4 stroke 115 with only 14 hours,,it had been running perfect however today wheni took it out it had very little power as if it wasnt running on all cylinders,,intermittently it would level out,,,any ideas,,i usually fix my own stuff however all my old engines have been 2 strike carb engines

[@hotheadzmarine]

Clogged injector possibly. That low of hours indicates a life of sitting with old gas in the fuel rails. Search some videos on how to clean your own injectors. Sounds probable. 👍🙏

[@charliesmith9528]

@@hotheadzmarine I pulled plugs today and 3 out of the four plugs looked great,,3rd cylinder spark plug was black unlike other three..im assuming this is cylinder that is mis firing,,will a clogged injector make the spark plug black like this ?

[@hotheadzmarine]

@@charliesmith9528 no, a clogged injector will not cause that. Could just be a bad spark plug or coul pack.

[@outdoorsman0331]

Nice video but my # 4 plug looks bad black and oily like a ring or valve problem on a 2015 Yahama 115 skips bad, could that be a injector problem??

[@hotheadzmarine]

Could be a few things, I'd start w\ compression test, then spark test, injector fire, then injector. swap components from a known good cylinder to verify if you need.. thats a good way if you do not have a scanner.

[@outdoorsman0331]

@@hotheadzmarine Thanks for the quick response hope its not a compression problem on a 2 year old motor i will check tomorrow

[@hotheadzmarine]

@@outdoorsman0331 Could be as simple as a bad spark plug honestly.

[@outdoorsman0331]

@@hotheadzmarine Thanks for all the help going to get new plugs this morning i will let you know if it fixes the problem

[@hotheadzmarine]

@@outdoorsman0331 Your more than welcome, hope we can help you.

[@joshuaivalu3718]

There's 2 coils top coil has #1 and #4. And bottom coil has #2 #3. Bottom coil with#2 and #3 no spark. But I switch coil and work other way around. What would be the problem?

[@hotheadzmarine]

Bad coil. Replace. Good diagnosis procedure by the way. Hats off to ya

[@kenmoses8]

Is it possible to have a “bad” injector or spark plug, but engine runs “perfect” at lower rpm? Add gas past 2000 r.p.m and the engine almost chokes, sputtering violently. Lay off the gas, engine resumes to normal. Drive it for an hour at slow speed thinking it might be bad gas and then engine all of a sudden runs fine at all r.p.m.... Day 2, same exact process starts over, an hour later, perfect...

[@hotheadzmarine]

Ken Moses, hello thank you for your question it's really an in-depth response that may not go well in this environment but it sounds like you have a high pressure fuel delivery issue

[@BubbaC85]

Did you ever find the problem?

[@hotheadzmarine]

Let me state I am well aware spark plugs should NOT be installed with any power tools. I have stated it over and over in our shop. The tech here was new at the time and I failed to correct him.

[@emilyduron3004]

I have a motor that I think is ok but wanted to let you listen to it and see what you thought. It idles and a little shaky, but give it just a little Throttle and all is good. Only when prop is engaged. Is there a way to get a hold of you?

[@eallanboggs]

Am I the only one that uses a Mechanics Stethoscope to listen to injectors to find out of they are pulsing or not With the engine running you put the scope probe on each injector and you should hear a tick, tick, tick If not either the injector or wiring Does this tell you if the fine screen in the injector is clean or not? No

[@hotheadzmarine]

No we use them all the time..smart business using them. Good job👍

[@Marcos_reyna]

I didn't know u could turn on the engine with just the hose connected there. I thought it needed to muffs to be able to turn it on

[@hotheadzmarine]

You shouldn't run it there BUT as we mentioned I think in the video it was getting a new water pump while here. Thanks for your comments

[@charliesmith9528]

Number three cylinder plug was black when i checked the plugs today,,,

[@hotheadzmarine]

Gas fouled, change the plugs and see if its resolved. could be a stuck or leaking injector but if stuck open the cylinder would fill with fuel.

[@scottjess1556]

You can buy those fuel pumps from multiple places

[@hotheadzmarine]

Cool. You gotta a source you could share?

[@tonykourounblis1854]

@@hotheadzmarineeBay

[@edwardarmstrong6416]

This is us

[@edwardarmstrong6416]

Let's catch plugs and clean injector

[@jerrychf]

So the spark plug fail right? I saw you guys swap the spark plug from no.4 to no.3 and no.4 cylinder remove the injector but it nothing happen when running engine? I was facing something similar problem with my F115a. It happen misfire at below 1500 rpm but not all the time, after 1500 rpm it run perfectly, that mades me guess for 1 of cylinder misfire at slow speed.

[@SEOKLADUCKIN]

Change all 4

[@pedropablogranados7080]

Hello in what cjty do you have the business

[@hotheadzmarine]

Huffman Texas

[@pedropablogranados7080]

I have the same problem in my yamaha 150 hp 4 stroke 2018 and anyone mechanic find the problem but i live in miami florida

[@pedropablogranados7080]

Thanks for answering

[@hotheadzmarine]

@@pedropablogranados7080 ABSOLUTELY anytime. Thank you Pedro

[@pedropablogranados7080]

I have one question if you can help me,what part do this problem

[@saracopeland9627]

your test re the water pump is completely wrong. you need a water tank to submerge leg in or muffs for the impellor to even work, the water does not change in pressure as it is simply being circulated around and through the cooling system under mains pressure on the hose. Just fyi

[@hotheadzmarine]

Lol.. no kidding. Did you listen to the video stating water pump was being replaced as well. Why is it people take time to make contradictory, negative comments on people's posts. We should all strive to less negativity in an already demeaning online world. 🙏🇺🇲 ps. You are not completely correct either as it is a flush hookup that circulates water throughout the entire cooling system. Hence the word flush.

[@Nobamaable]

@@hotheadzmarine I wouldn't let you clowns wash my boat let alone work on my engines... pathetic!

[@captlucky2320]

It's a Yamaha it's always a sparkplug I hope y'all are not a Yamaha dealer I done seen so many things done wrong

[@hotheadzmarine]

It's not always a spark plug!! "I done seen" LOL..dont freak out man. We're field engineer's 🤣 we actually repair them for half the $$ successfully..& NO, we are real mechanics. But yea no doubt we go about things in a manner the dealer hasnt been trained on..its an off the cuff video.

[@captlucky2320]

@@hotheadzmarine how you diagnose a wp on flush hose and say it's not pumping like it should cmon man that's bs but maybe you believe it

[@hotheadzmarine]

@@captlucky2320 did you listen to the video or just watch ? It was in for service and the misfire. The pump was being replaced afterwards Sir.

[@hotheadzmarine]

@@captlucky2320 1..just one of the customers requests was to replace the water pump impeller kit.

[@redsoxwinagain2007]

Nice, always get a younger tech to stand in water while pulling electrical connections off a running engine. Misfires should show up in the YDS log (depending on the year).

[@hotheadzmarine]

Yea, that 12 volts with extremely low amps is a killer. This isn't 500 VAC. Take care.

[@mattcroft4299]

Flush port is only for engine when NOT running . How do you expect the impeller to pick up water without muffs on! Glad you're not working on my motor.😂

[@hotheadzmarine]

Thank you for watching the video. I hope it helped you in someway other than just to report negative comments and already negative online world.. if you would have been paying attention to the video you would’ve heard me say we were going to service the water pump afterwards however, just for the sake of engineering conversation at idle with 35 to 42 psi of water pressure coming through the hose it is backfeeding the water pump and the water pump and is not running dry. But once again, thank you for your comments and watching the channel. We appreciate you..

[@mattcroft4299]

@@hotheadzmarine I understand totally that the pump will back feed. But You cannot use a flush point to then show the impeller is not making the correct flow or pressure, your supplying water to its output side, not the input. That is why you use muffs or test tank. The water supply must be on the gearcase, not flush point.

[@Nobamaable]

You don't use a power tool to put spark plugs in... what a bunch of knuckle heads ; \

[@hotheadzmarine]

Did you read my comment