?? fuel issue on low revs

[russellh2]

All of the below to be done with motor in water and the cooling system is working correctly and pumping the correct amount of water.

Some non destructive checks / Possible fix:-
1...Check all flexible fuel lines and connecters that you can access / see for leaks / weeping when the motor is idling.
2...Check all flexible fuel lines and connecters that you can access / see for leaks/ weeping when the motor is running above idle, especially at the RPM when it starts to bog down.
Replace defective hose/hoses/connecters.
3...Buy a can on Carburettor / Fuel injector Cleaner.
3a..Start engine ,let it idle until it warms up to operation Temperature
3b..Remove engine cover to access the carby throat.
3c..With engine idling put 1 squirt of cleaner into throat of carby for 1/2 second and see is engine idles better - Note that motor may increase engine revs for a moment them settle down, if this occurs apply another 2 or 3, 1/2 second squirts into carby throat and monitor if you see any improvement in idle
4...If idle improves it shows that you have partial blockage in carby, and probably need to replace the fuel filter/s
5...Remove all fuel filters - Place a glass container under the fuel filter/s to catch fuel as you remove the filter, catch escaping fuel in container, aside the container and reattach fuel line. Let container containing fuel sit for a few minutes and see if there is any water in it - Note that Fuel and water do not mix.

If the water coming out of the motor is very hot it could indicate that the thermostat is faulty causing overheating engine therefore causing fuel vaporisation

Good Luck

Feedback appreciated.

[skronkman]

Yep, that looks like your fuel filter/ water separator. It should be changed over every year or so. It may or may not solve your problem but it's a much better place to start than cutting into the floor of your boat. If you can get your hands on a portable fuel tank with fittings to connect your motor then ou could try and run your boat from that as a test to see if it runs fine. This will help narrow down where your issue lies (in the fuel lines/filter/tank or in the motor). There are usually more inline fuel filters under the cowling too you can check/replace.

I'm not sure what motor you have or setup (looks like a Johnson 4 stroke, I think same as the yammy powerhead) but if you have a fuel bulb you can try and squeeze it while the motor is playin up at low revs, if problem goes away while squeezing this will also help narrow down the issue.

How long since you had a service? Checked/changed your plugs lately? Worth checking.

Often when you have a fuel blockage it shows up as a problem at high revs under load not low revs. I know it seemed to be triggered by you running the fuel out of it but sometimes it's just coincidence and the problem is not caused by what you think triggered it. Best to start with the easy and cheap things first before trying anything expensive and way before anything destructive.

If you can narrow it down to the fuel lines or the motor with a separate tank first, then We can try and troubleshoot more from there if you're interested.

Is it a carby or efi motor?

Cheers

[Mattblack]

I'd upvote the Russellh2 and shronkman if there was an option.
Could the problem be something as simple as too much 2 stroke oil being added/injected?

[Mjacc]

I'd agree with the above. I had a similar issue. although not stalling it was close on low revs but under high revs completely fine n you wouldn't know there was an issue. (Yamaha 2 stroke)
Got it serviced and changed out the old plugs which had become gunked up and it runs really well again. Not saying you have the same issue. But good to start with the cheaper options as stated above

[Fahro]

I have the same engine as you, except i've left the VRO Pump on so it mixes its own oil.

I've also had a similar problem

Once you've done all the simple checks; clean carbs, spark plugs, fuel lines and it's still playing up, it might be your power pack on the way out

[Sinsemilla]

take apart and clean the carby out and change plugs. That should fix your problem

Anth

[skronkman]

Once you've done all the simple checks; clean carbs, spark plugs, fuel lines and it's still playing up, it might be your power pack on the way out

Yep, coils and plugs are near the top of my guess fix list too based on the specific issue (less so the CDI/powerpack which isn't a cheap fix!) but I reckon there is some more narrowing down of the where the fault lies before going here. Carby cleaning and testing coils/spark can be daunting for a lot of people.

[canned_tuna]

If you head down the carby cleaning path yourself just be aware it produces a fair amount of smoke during the process. Good luck with it I hope you sort it out before Bermi

[smile0784]

Ill have a look at all those thinks tomorrow if i don't fet work tonight.

Thanks for all the suggestions

Its a 115 johnson 2 stroke with carbies

[Nude up]

I picked up some **** fuel from Drysdale once car and boat, boat would start get up on the plane then the engine would cut out 5 mins later it would start then repeat the same process. Turns out it was water I had to pull the tank out because of brown muddy lookin stuff, I pulled the carbies off the 130 Yamaha and they had a green jelly like stuff in them.
Once all cleaned up never had another problem however my car cost $2500 new pump injectors etc.

I would remove the fuel filter cut it open and have a look do not skimp do a proper job now it will save problems later