Outboard fuel pumps
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- เผยแพร่เมื่อ 7 ก.พ. 2025
- In this video I do a couple of crude fuel pump tests using a pressure gauge and then replace the one-way valves in a four stroke EFI Mercury low-pressure pump. I also show the metal reed valves in a Yamaha fuel pump from a two stroke motor.
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Excellent and ageless video - helped us troubleshoot and repair our Mercury 30hp, 4 stroke, EFI fuel pump. Amazing how we can count on you mates from down under and not from our own here in the USA! Thank you so much!
You're welcome Joe. :)
have to say, really appreciate your uploads. no boat experience, just bought a boat and with your videos i have serviced the impeller, carby, shaft seals, lower unit oil change. and now the fuel pump. thanks very much stu
Glad to help. :)
I had exactly the same problem with the fuel pump in three boats, and it took weeks for the mechanics to understand what the problem was. The engines would be running and then suddenly there would be a power loss, like a lack of petrol. We changed everything: petrol tanks, pipes, everything. We even changed the high-pressure pump, but in the end, it was a mechanical pump. One of the plastic gaskets was off. The confusion was as when the problem was happening and i was turning the key off and starting the engine again the boat would run perfectly fine, but after an hour or more, the problem would return.
I bought three new pumps as the Mercury dealer in Greece said there was no repair kit . I am extremely happy that my boat and engines work perfectly again. Thank you for the wonderful video.
Your videos have made me a hero :)
In Egypt, we have hundreds of live aboard dive boats and each boat has a couple of RIBs with 40HP yamahas.
Now our sailors over here have hearts of solid gold, but they are pretty careless with our equipment. We all suffer terribly with keeping the outboards well maintained.
So after watching your videos, I started doing these odd jobs and it has had a huge impact. Sailors from other boats keep coming over for me to fix theirs!!!
Thanks for the greta videos!
Great to hear! Someone has to keep these old motors going. :)
Here from America , I just recently rebuilt my Mariner 200hp had the block bored and had new pistons , bearings and more . Runs like a beast . I've been a mechanic for alittle over 20 years but still learning everyday , lol
Nice one, glad to hear is running well after the rebuild. You're dead right though, there is always something new to learn!
If you don't mind telling, how much was the rebuild versus the price of a new 200hp engine?
This plus the VST video saved me a fortune. Local marine shop couldn't figure out what was going on. These two videos were exactly what I needed to do it myself on a 60/40 EFI mercury jet. Thank you SO much! Very valuable videos.
You're welcome Jeremy, glad to hear the vids saved you some money. :)
Thanks again Stu, you are a life saver. Ron from Michigan USA
Awesome video this video explained how the fuel pumps work didn't know much before it. I wish you would put videos up more often like two or three times a week don't worry about editing them just put them up real time I'll still enjoy them a lot thanks
Hey Joe, glad you liked the video. I am working on finding a way to make more time for at least one mid week video each week. I had started doing short "quick tip" videos and I really need to get back to that.
Oh, and I also have the 'dangarstu' Instagram account for little midweek bits and pieces.
Great video Stu, you always make things clear and seem easy. Thank you for your tips. I often suggest your channel as reference when people are asking for certain outboard problems, Cheers Rob
Thanks Rob, glad you liked it and always appreciate people spreading the word. :)
Great video!!! I have been having fuel problems I just changed the priming bulb and it didn’t work so now this will be my next thing to check. Again thank you sir you are a big help and I did learn a lot from your video.
You’re welcome, good luck!
Very informative. Gotta buy you another Fosters. Bought an `86 90hp merc w/16ft runabout. Been running good gas and Sea Foam. Got it going 36mph top speed. Gonna rebuild/replace the fuel pump for maintenace. Hope to get more speed but I think that`s all she`s good for (36mph).
Thanks mate, glad the vids have been helping you. :)
Hey I just wanted to say thank you for all your videos very informative you do a really great job thank you again
Wow, extremely thorough on the wire wheel about the old loctite at 8:15 Great job on that.
Dammit mate I needed this 18 hours ago.. Thanks for the video regardless all great info once again.. Successfully cleaned and tuned my carbys just from a couple of ur videos so far, confidence inspiring indeed. Saved me a few hundred atleast
I've heard that a few times! I had been meaning to do this one for a few weeks too... Glad to hear the videos have been saving you money. :)
Great video. I noticed on my old pump that after removing it to test it you can pump the button plunger that goes in the motor and feel if it holds suction with your finger over the pickup side and feel the pressure on the outlet side if the pump is good.
hey that looks just like my 4hp yamaha fuel pump I thought was leaking internally but was the cheesy finger clamps. changed them out with SS clamps like you showed on one of you other videos. the hand pump is a must have for pressure leaks. good video. Thanks
Thanks mate, those pump / gauges sure are useful, that's for sure. :)
Dangar Stu every new youtube account I make your the first channel I sub to. I'm trying to diagnose my 25 efi merc right now and I'm pretty sure its the pump.
Great videos! The one on the VST really helped me with my 2003 Merc 40hp 4 stroke. I was also surprised to see I can buy a new low pressure fuel pump for cheaper (96USD) than a company wanted for the rebuild kit (120USD). Thats if they had the right kit number. Keep up the great videos!
Thanks Jim. It's weird sometimes with parts. It also pays to look first as the prices can sometimes be surprising.
Another great video from you Stu. I have two of these guys on my Yamaha 150. I was told both were replaced for preventive maintenance, but now I know how to test and overhaul them if needed. They are less of a mystery to me now! We have ethanol blended fuel here in the US that isn't the best for boat fuel systems. I wish that they would go back to good old regular gasoline!
Easy way to check those is by loosening the mounting bolts a bit and then give the primer bulb a squeeze, if they're bad fuel will leek out of the hole in the back that Stu pointed out in the vid. They're easy to rebuild but a new one is only $40.
Don't tighten the mounting bolts up too tight, they only need about 6 ft lbs or so.
That's a nice quick check for a leak in the diagram, I like that.
Yeah, we have ethanol fuel here and the government mandated that all service stations must sell it. However along with that law is that the blend is a maximum of 10% and bowsers have to be marked (in most cases it is very poorly marked, and hidden by other 'power words' ). So generally if you stick to the major brands and use 95 or 98 RON fuel you are OK in Australia. You can get 91 non ethanol in many servos but you have to be careful as the 10% ethanol is often in the same pump .
In saying that we still get bad fuel! We filled up last weekend and ended with 50 litres of bad fuel (diesel+E91 in a supposed 95 pump!) last weekend which killed my engine with in about 500metres from the dock! So now I have another major winter project - or a new motor - to be done by October.
Ron Powell Wow Ron, sorry to hear about that. I guess the whole ethanol and water issue is more widespread than I thought. They do sell non ethanol fuel here in the US, but it's very hard to come buy. A search in my state (New Jersey) shows only two places to buy it in the entire state. (It's a big state here too!) And none of them are anywhere near me. Best I can do is try to burn the fuel in the tanks ASAP and not let it sit. I also dose it good with an ethanol fuel treatment with every fill up of the boat.
Sent this Vid to my friend perfect for his motor- Thanks Stu
Glad it helped
Thanks for pulling the Yamaha pump apart. Now I see why a lot of places just sell the pump diaphragm.
Yeah, it is certainly the most common part to fail.
@@DangarMarine where can i order the Diaphragms?
thank you for you time to make this videos.
Great video as always. Really enjoy watching them, and I learned a lot. Thx
Love the "vintage film stock" that you used to take us back to show the one-way valve diaphragms. Don't worry about making "lame" videos, there's no danger of that happening. Oh, and as for giving your viewers the shirt off your back, that's wonderful of course, but if it goes any further than shirts, it might become a problem. Thumbs up !
Thanks Stan, sometimes videos don't quite go to plan but because I'm always doing them at the last minute my options are either to just put it out as is, or not have something for that weekend. One day I'll find a way to make the time to do them much earlier and do a bit more research first!
Excellent video, as was the VST service video. Would like to see more. Learned a lot. Do a video on servicing a 60 hp efi outboard. Love the tips and tricks!
Just wanted to say thanks for your taking the time out, in making your videos. Great stuff! We all enjoy them, and are so helpful... I'd like to request, when you find the time.. Will you make some more videos, covering motor Bogging...Why?? Is it in relation to Fuel pump, or in the carbs? Mainly, just more videos on Fuel Pumps, and Carbs... Thanks again, Don.
Hi Don, glad to hear you've been enjoying the videos. Doing one on bogging and not achieving full RPM is a good idea. I'll have to think about the best way to do it but I'll come up with something!
Great!!
Hey Danger! Your videos are always my first choice when marine work is needed so I have a question. I have a 2013 yamaha fxca 250 and recently on the water was having fuel pump issues. (Engine dying completely as if starved of fuel and primer bulb being the short term solution) Got it home and investigated the low pressure fuel pump which is electronic and absolutely no fuel coming out of the line which should be feeding into the VST. Went to the fuse box and found the fuse was blown. switched it out and fuel pump worked for a short time then nothing. Fuse blew again. Tried bigger fuses and they all have blown. Is my pump shot or is something else causing the fuses to blow? Thanks for all the great teaching!!!!
Great work Stu!
Thanks Will! :)
Hey matte great watch just wonder the low pressure fuel pump to replace instead off rebuilding I thought you mentioned the price was reasonable was quoted $800 -$600 today
Great video as usual. I am motivated to trouble shoot my Yamaha fuel issue. Thanks
Comedy gold stu.. hahah I have no idea how you manage to keep a straight face!!
Anything's possible with editing! :)
Cant stop watching the second hand on the clock
2002 honda bf40. Original fuel pump. Is it possible that engine oil makes it way via the pump plunger/camshaft inside the pump? I noticed very little weeping of oil underside the pump assembly/gasket. Does not smell gas. Excellent video! Thank You
Good video.I thought maybe you would be showing a fuel pressure gauge installed in-line to show actual pressure it was producing.I just acquired a fuel pressure gauge to install between pump and carb. on my 85' Johnson two stroke to test.
I used the fuel pressure gauge in the original video that fuel pump came from, but unfortunately the boat this goes on is no longer hear so I can't test it directly. It is a good point about testing one in the future though. I'm normally only interested in fuel pressure with EFI motors but it would something worth checking for carburettors too.
Haahaaahaaa!! I think this is the first time I have been made to laugh while viewing a marine repair video!
So you gave him the shirt off your back!! Love it!!
Hi the vidoe is a big help im struggling to find the one way valves for my 4 stroke engine where did you get your from please?
This video is awesome! Where did you get this Marc rebuild kit? I can’t find it anywhere.
Do you know the torque for the bolts that attach the low pressure pump to the head?
Where did you get the diaphragm from for merc pump also do you know where to get the bottom plunger assembly
very good presentation I go by Jake I'm 73 and in poor health but I enjoy watching your presentations. One question, we have an old Johnson 40 hp. with the oil being mixed by an injection method,do you have a video showing how to rebuild the dual carbs if you do please let me know thank you.
Hi Jake, I don't have one specifically on those carbs, but other videos on cleaning carbs and installing carb kits that you may have seen. By dual carbs, do you mean that each unit is feeding two cylinders? I've got some carbs like that from an old V6 that had 3 dual carbs on it. I could do a video on that carb if I can find it.
mine squirts out fine on the boat from the outlet...I cleaned the VSP VST was wondering if carb cleaner is ok to flush through it or will it eat the rubber???
Just happened to see this great vid. I have -04 BF50A and the oil is getting thin and it smells like there's gas in it. How common is it that gas leaks through pusher rod opening? Can the gasket and rod be changed without buying the whole pump? This may be also a thermostat problem since here in Finland we have pretty cold sea at spring and autumn...and practically always if comparing to Australia😊
great video!
Thanks mate. :)
First, thank you for taking the time to put together these very informative videos...Now, question about fuel pumps.. I'm having an issue with an 1987 Johnson 90hp v4, which I just purchased and have it on the water several times no problems.. But, now it boggs down, doesn't die, just boggs down.. seems to happen once you try an open it all the way.. Things I've covered so far...One, I changed out the primer bulb, and switched over to a different tank of fuel.. So what next?? thanks Don..
I would make sure the carb bowls are full of fuel by draining one straight after it happens. If they aren't it could be a dodgy fuel pump. If they are full it could be a problem with blocked main jets meaning the carburettors will need a clean and perhaps the float levels set.
was awsome love this site got all my gears now happy as larry lol cheers m8
Hey Troy, glad to hear you've got all your gears sorted out.
Where did you buy the low pressure fuel pump diaphragm kit at? I can't find any for sale. New subscriber here, great content!
I learned so much from your video. Si fu.
Felt like Dangar today, did a powerhead swap on my Johnson 115. The VRO pump makes me nervous though
Nice work. With the VRO pump just make sure you start up with premix oil until you are sure that the oil in the reservoir is being consumed.
Can you do a video that shows what are the most important or crucial tools/gadgets/testers to own when a noobie is considering to maintain and service their own outboards?
Sure, that's a great idea. I'll try to get to that one soon. :)
Hey stu! I know you get a lot of request for vids. I have a request that im sure most would like to see. When you google reading a spark plug, the info is vague and hard to tell. A quick tip on spark plug color reading would be great and a lifesaver. Could save someone from a piston rebuild by reading plugs. I myself just know dark is oil and white is lean. Thanks and please keep up the great work!
Good idea, reading spark plugs is an important thing to learn about. I'll start keeping interesting spark plugs in a tray somewhere and when I have enough of them I'll do the vid.
Dangar Marine I have a 1966 Evinrude 5 hp, recently replaced a leaking fuel pump, connected everything and it fired up but it won't stay running more than 5 seconds, cleaned the carburetor the previous winter and also replaced spark plugs...any ideas on what the problem is?
That sounds fuel related. Try choking right before it kills and see if it keeps running. it could be something else but i would start there. Mine did very similar after i rebuilt my fuel pump and all fuel lines and carbs. I just KNEW it was electrical. I bought an extra fuel connector and ran fresh fuel on a different tank. My problem was i was sold water as fuel from a marina. Since i just bought the fuel it didnt even cross my mind. Pulled my fuel/water seperator and it was FULL with water! Fresh non-ethanol fuel my ass! The marina screwed me. So try fresh fuel this time. Or dump some of your fuel in a glass jar and see if it has water in it. Let it sit for a lil bit and you will see the seperation if it is bad. Hope this helps and good luck
bigfat hotdog it will stay running for a few longer seconds on full choke but still dies... just put new fuel mix in a week ago... could the carb have gotten gummed up only 4 months or so after a good cleaning?
bigfat hotdog also it only starts using starting fluid but once that's gone it dies immediately
How good was that black and white valve video cut in!
Thanks Matt!
hi i was wondering if that plunger in the back could leak oil into the fuel ive got a lot of smoke like its burning a lot of oil 4 stroke 40 merc thanks
Thanks for the video, my suzuki df30a year 2019 cuts power over 4000 rpm after 5-10 minutes ride. It starts and runs very smooth and perfect. Can you give any idea; is it the low or high pressure pump?
So you should not be able to suck air from inlet or blow air through outlet, right?
I have 2 of the pump at 11:17, Yamaha. When I squeeze the fuel bulb, fuel leaks out into one of the holes where the mounting bolts go. That’s very bad right? I’m surprised that both of the pumps I have do the exact same thing.
Could be a couple of things. Either the diaphram / gasket in the pumps are bad or the needle and seat in the carburettor isn't sealing and the crankcase is filling with fuel through the throat of the carburettor. I would take one of the fuel pumps apart first and carefully look for tears, holes or pinched sections.
can you tell me which fuel pump repair kit you used? I need to replace those reed valves in mine and cant find a rebuild kit. thx
Thanks for this. I have that very fuel pump, bu my problem is that there's no water flowing through it. Can't figure out how the cooling channels are set up in that pump. Have tried vinegar and poking with wire, but no luck. Any advice for me at all? Thanks for all you do here, chief.
SOLVED: So I found a solution to the problem. It is a fairly straight shot through to the tell tale hose. It is pretty narrow though, and with age, it gets a little jagged in there, which can catch a lot of sand and shell debris. I used penetrating oil and various size zip ties to "saw" my way through. Required much more physical effort than clearing hose or tell tale, so don't be afraid to lean into it. Hope this helps someone else.
Hey Dangar Stu, what's the best place to or these parts from in Sydney or online?
I got the 2stroke fuel pump . Tohatsu
You wanna check the clock battery behind you, bud, looks shot! Great videos though.
I need to know how to disassemble the cam shaft button that pushes on the diaphram! Thats all thats bad on my engine.
hi stu i have the honda bf90 and got the shock of my life because as always every time i use my boat in the sea i get home and next day flush engine properly. well the last time i used my boat i took my top cover off engine and to my shock at the side of my thermostat there is a metal covering with a hose attached well it was all corroded at to buy new metal cover i would be happy if you could show on your videos where the water system flows so that i might be able to watch for any more problems by the way i have the full honda bf 90 diagram pages if you would like me to sent a copy to you i will do so but watching your videos are much more informative
Hi Jimmy, I've been meaning to do a video on the full path of the cooling water for AGES! Thanks for the prompt to bump it up the list. Stay tuned!
I have a 30hp Mariner EFI about 4 years old. It runs fine from cold. If I stop the engine after approx 2 hours and leave for approx 1 hour it will not start. It turns over fine but will not start. If I leave the engine overnight it will start up again just fine. Any ideas? Fuel is always filtered into tank and a fuel/water separator is fitted. Engine is serviced annually. I have enjoyed your blogs over the years and have begun searching through them again to help find a solution to the above problem. Cheers.
Does anyone know where to order the rebuild kit or even just the little valves and rubber pins from?
Hi What caused the fuel pump to fail? Because in the span of 6 months, he changed three times, and I don't know why
thank you! im struggeling with my boat, a mercury 90hp 4 stroke 4carb engine, on full throttle it wont go full rpm.. i opened my fuel pumps (1 pump serving 2 carbs) and found the "sealant gasget"? full of some white powder, tho i cant seem to find a leak, tho there was some sandlike sort of grainy stuff in the chambers, so i cleaned them out, hoping it was the sinner, maybe blocking some valves or something... and i dont want that stuff in my carbs. cant seem to get my membrane off tho, but i cant see any damage... i see some fuel getting into the water but i cannot find where it comes from... its an 2001 model.. do u have any ideas?
My 06 mercury 4 stroke efi is losing prime on warm starts. Could this be a possible issue or does it sound like high pressure vst? I've replaced primer bulb and main fuel line but problem seems to be getting worse. It takes about 10 attempts to start but once it cranks the engine runs fine.
hi mate, I have motor BF50A that has problem with the fuel pump. But I cannot find where I can buy the rubber. Could you help to show me where should I get it?
I have 60hp Merc, would a high pressure or low pressure fuel pump cause motor to not ramp up past 4000rpm?
i have a yamaha f115 with a similar pump. i opened it up because im getting fuel in the oil. the diaphragm has oil on the fuel side is that normal?
Excellent video! Can anybody tell me if there’s a gasket between the head and the plastic back of the pump?
Could the bad valves cause fuel to get into the oil
Love your videos Stu, so Briiliantly simplified for lamen like myself..
My mariner 40hp efi has been beeping a continuous warning beep..
Apparently oil pressure, or overheat. I've replaced oil, oil filter, cleaned high pressure pump, replaced both fuel filters and bought all new fuel lines... Still getting the dreaded beep..
I'm going to replace this low pressure pump now as the cooling water runs through it so hoping it might help?
Any other suggestions would be amazing..?
We are working with this exact pump and encountered a problem getting one of the mounting bolts to thread when we put it back together. We backed all four out carefully just one time and three went back in well while the other won’t latch onto the female threading. Do you have a recommendation for how to correct this so that the pump can be fully reassembled? There is no visible issue with the bolt and so I figure that the problem is inside. We did switch bolts and found that any one of them works in the three good female threaded parts.
What’s the first thing you would check in this scenario, boat runs great except for at full speed RPMs drop and rise until I slow down a bit?
You are awesome, One of the best Channels on TH-cam for boating. Could the fuel pump being old /weak cause a weak jet from my carburetor/ not enough fuel?
Yes, if the fuel supply isn't high enough the level in the carburettor float bowl will be too low and the mixture will be lean. It could be a carburettor problem too though.
Dangar Marine, Thanks , I rebuilt the fuel pump. Think I've got it sorted out , still some adjustments to do. But I think it's time to replace the tachometer
Thank you for video! What part number gasket kit for fuel pump?
My son has a 4 stroke 9.9 hp evinrude, 1999 model, fuel pump isn't working and you can't get a spare pump, it the one with the rod that works the diaphram, any ideas please
At the begining 3:30 U pumped air into the outlet and exhausted immediatly when u release finger.
Does it means that if you pump in the inlet
The outlet will release also immediatly?
Does it means that the faulty valve is always open?
The valves should only allow air to pass one way easily. If you pump into the inlet it should flow straight out the outlet. Yes, a faulty valve with be open allowing fuel to flow in either direction because it is always open.
I can't find the kit for this I need the exact black rubber plugs but I'm not sure on the size
You vids are 👍👍👍
Thanks mate. :)
I have replaced my low psi fuel pump and still have no fuel in the water separater. What do you recommend?
Hi Stu. I have a problem the engine Flood`s on all 4 Carbs, when turning the Key on?? I have sat pressure on each, carb on my work bench, and nothing comes out of the intake? But when it is put on the engine
it Flow`s out??? Could the pressure on the pump be too high?? It is a Mercury 50 hp 4 stroke 4 cyl from 2001 ( not the EFI model).... Enjoy your Videos.. Hope you can help mee. Sincerely Mogens Madsen
from Denmark Europe..... Have a good day.
Would want to know why the engine gets bad real quick and our motor is Yamaha 40hp 4 stroke. I would want to know why our engine get warm. I was wondering if the oil is not working well
How many fuel pumps does a BF90A Honda outboard carbureted have
I have a question concerning the "problem" of the pump you rebuilt not being perfect (according to the pressure test) after your work..... What if you had wet or dampened the pump with some gasoline prior to the after-rebuild test ? Would things not have been happier inside the pump if the new valves had some liquid at least passed over them prior to being pressure (or vacuum) tested? After all, they do deal with liquids, not air. I do agree that it's good to test on the bench rather than out on the water, but just wondered if the test was completely fair to the newly installed parts.
Stan, you beat me by a few minutes. I agree that those valves should be 'lubricated' for the tests as they are not air tight, in fact they are not even fluid tight. They don't actually have to seal , just be very restrictive to reverse fluid flow as they are being pulsed very quickly . That pulse speed means that fuel cannot reverse flow easily .
On the KT100 go karts ( carb and fuel pump in one unit!) you need to put a squirt of WD40 on to the needle seat and on the one way valves to be able to set them up correctly. I use WD40 as some other cleaning fluids are not nice to nylon / plastic parts. The alternative is two stroke oil diluted 50:50 with kerosene, not petrol ( it evaporates too quickly and is too flammable for bench testing stuff)
Out of interest I'll squirt a bit of fluid in there and see how it changes. I think the test is useful enough just to know that the case has sealed properly (certainly saved me this time!), but if it was possible to get a better indication of the health of the valves it would be good. I think the trouble is, that as you both say, they will never hold air pressure fully so drawing a line between serviceable and needing replacement would be tricky.
I just tried this on my spare two stroke fuel pump and it worked OK.
Using an old 12volt tyre pump ( a K-mart one the kids use to pump up balls and bike tyres) I connected it to the fuel pump pulse line via a T piece. The open end of the T piece went off to a ball inflation spike that acts as a restrictor and to allow the pumped air to escape so I didn't over pressurise the fuel pump. The tyre pump pulses are enough to operate the fuel pump. The fuel out line was connected to a measuring jar, the fuel in line to my boat fuel tank . With the air pump running for 1 minute I measure just under 300mL of fuel delivered- which is more than enough for my 50hp engine. So if you have an old 12volt air pump around (probably even one with worn out one way valves would do, or take them out- then you can just connect it to the fuel pump directly) you have a great test unit !
I got a 1986 bayliner 125 outboard motor, starts with no problen but when i acelerate to go fast ,the power go off and on off and on , what it can be , the carbs, or fuel pump? Or someting else?
Hey stu I really need your help I don’t have any good mechanics or Honda dealers near me , I’m having a issue with my motor I constantly need to prime my ball and notice it’s never stays hard and when idling it doesn’t stall but shakes pretty bad . I can’t find any info on the part I need or if I should take it out and check the fuel pump . I’ve replaced the gas lines fuel filter clean gas fuel water separator and nothing any advice would be great !
what kind of pressure gauge pump is that at the 10 min 30 sec mark?? great video as always
This one I presume th-cam.com/video/lnhZFn5gkG4/w-d-xo.html
good vid
Thanks you!
Quick Question- I am cleaning the carbs on a 2001 30hp 2 stroke Yamaha for my dad, he let it sit for 5 years with ethanol gas in it. So I cleaned the carbs dumbed the old gas and had him get new ethanol-free gas it started right up but after a tank of gas was idling rough. I pulled the carbs and the jets were clogged again not as bad but some of the jelly was in the system still. So can I open and clean the fuel pump without having to replace gaskets or diaphragm? I also ordered a new hose and primer bulb and plan on scrubbing the tank clean. cleaned fuel filter also again.
or do you think to clean the tank, fresh gas, seafoam, new hose, and primer bulb, with clean carbs and fuel filter with clean it out good enough?
what about the nocking sound coming from it sounds like worn cam or shaft ??
Mine bogs down at full throttle. Occasionally when it's running fine it just runs out of gas and quits quite disturbing when you're running across the lake at full throttle. An old Mercury pretty sure it needs fuel pump rebuild. I'll take it apart tomorrow and see what I find.
Sounds like it could be a candidate. Good luck!
I took apart the fuel pump and noticed some fuel on the exhaust side of the diaphragm also noticed unburned fuel was coming out of the exhaust. The diaphragm itself looked good but obviously it was allowing fuel to pass in the wrong direction. Replaced the diaphragm and took it out to the lake for a test. Had full throttle again and actually had a couple of hundred more rpm The rebuild kit was only $8 on ebay so I saved a bundle over taking it to my mechanic who is very good but also very expensive . Very simple fix.Your video gave me confidence to tackle the problem thanks.
My outboard is doing the same thing I have a gas filter between my tank and motor seems to be when it's full with just a small air bouble runs fine other then that I have to keep priming the ball when I'm full throttle
So 2 strokes have similar pumps like the 2nd one you took apart?... and also you said with the diaphragm cracked it would leak badly ... would that leak be internal or would you see a stream of gas floating in the water? I know this is probably a newbie question but I'm just that s newbie .. lol
Hi mate. It depends where they crack. You can get fuel leaking externally if the gasket is bad between the layers, but you can also get fuel running down into the crankcase making it run rich and have fuel come out the exhaust.
Dangar Marine if it runs in the crank case and out the exhaust would that make the engine cut off when put in gear , only when submerged ? I really appreciate all of your advice and help
You mentioned an O ring wasn't seated on first assembly of the Merc pump, I didn't see anywhere that you referenced it/showed it/where it is?
On the Yamaha pump, what does the metal valves seal against, just metal, or is there an O ring or something they seat against?
Lastly, what videocam do you use and what software for editing?
Thanks,
RichE
It isn't so much an o-ring as a thin gasket that goes around the edge of the pump's cover plate. The reeds on the Yamaha pump just seal against the plastic casing of the pump. As the vacuum tests show, they down really seal completely, they just restrict the flow in one direction enough to cause fuel to mostly keep moving in one direction. Camera is a Panasonic v770 and I use Final Cut Pro for the editing.
Great video on the fuel pump. I wish we had a guy like you here in the Atlanta area, someone who tinkers with older motors. My 1986 model Mercury 75 HP would generate a lot of work from you! As it is, I have to do it with a book and helpful videos like this. Question about fuel pumps: yesterday I serviced mine, trying to track down a fuel problem that is giving me some stalls and bad hole shots. The rebuild kit I got included a plastic 'cap' that fits over the end of the spring that contacts the diaphragm. My pump did not have that plastic cap, nor did I even know such a thing existed, because I always bought just new diaphragms, gaskets and check valves separately for pump service, never in a proper, everything-included kit. Because I never had that plastic cap, the end of the spring would always poking into the middle of the diaphragm. Could that have been a cause of my weird fuel delivery symptoms? Here's a picture of the spring: i.imgur.com/IcF3K9A.jpg and this is the plastic cap: i.imgur.com/5yeWJRH.jpg
Hi mate, can't say I've seen that exact fuel pump so I'd hate to give you the wrong information but it makes sense that something should be there to protect the diaphragm. Something else to be aware of though is that sometimes these kits come with parts to cover a range of outboards and not all parts are needed for your exact model.
Thanks for the video. I am trying to convert my VRO on 1996 Johnson 200hp 90 degree to a premix conventional direct fuel pump. I was going to run 2 aftermarket fuel pumps in series and cap the extra pulse port- will this work?
Hey Stu! Thanks for the videos brother! While watching your choke video I had a thought that may be my be the answer to my bogging at wot. Can you confirm please: The read valve on the 2nd fuel pump in this video (used on 2002 Yamaha 90hp), is what I have. Should both reed valves sit closed (touching the seat), when installed. If one is lifted enough to see that it is not seated (maybe 3mm gap), would that cause bogging at wot? I will need to confirm, but I think I have this condition with one of my reed valves. I am getting exited and cant wait to get home and check my pump. I will comment if that is the problem, because as you said, I have never seen an issue with those reed valves, but I may have missed this a few night s ago. Thanks brother!
I just re-watched your video on pressure testing lower units where you made your own pressure-tester. In this video I see you've bought a commercial hand pump pressure tester. How much was it and where did you get it? You still reckon a DIY version is good enough? Thanks for the video
Hi David, yep, DIY version works just fine, it's just a little bit more fiddly to use. The one I bought is like this www.ebay.com.au/itm/Hand-Held-Vacuum-and-Pressure-Pump-Tester-Kit-Brake-Fluid-Bleeder-Adapters-/291832545459?hash=item43f29340b3:g:GcMAAOSwc-tY7yHW
Hi, really enjoy your vids and hope your haveing fun on your new bike. I have a 15 hp yamaha 2 stroke, that I think has has a fuel problem. 3 times when the fuel tank gets below half full it has died on me. I can pump the bulb and it will start, idle about 5 seconds and die. Have cleaned the carb and checked the diaphragms and replaced the tank to motor fuel line and bulb, still same problem. Other than preasure, is there a test for the portable tank? Should I be looking elsewhere? Thanks
I would be looking at the pick up in the tank and making sure the breather on the tank is open. It is strange to get so far (half a tank) and then fail. I would also check that it isn't something unrelated like the motor overheating.
Dangar Marine Thanks, for the info on the tank. Have a steady stream comeing from motor when it dies. All 3 times we were fishing at end of day and motor had been stopped for over an hour before we started back to dock which was about 3 miles away. Probably the shrtest run we made all day. I will test the temp and let you know what I find. Thanks again.
Someby know where to buy the handpump or the type of it ,Thankyou