1991 Johnson 25 hp problem..

[Rost]

My brother owns a boat with a 25 hp Johnson on the back. Lately he has been experiencing a few problems with what I believe is his fuel bulb/line. Basically, when he trolls his motor bogs and quits. The only way it works is if he continuously pumps the ball. Strangly, this never occurs at WOT. And otherwise, his motor runs perfectly.

Is there anything else I can suggest for him to do other than change his fuel line and bulb?

Thanks

[Fishin4Life]

Has the carb been gone through lately. It sounds like it is starving or even flooding at low speeds. He might want a professional tune up. The motor (as I understand it anyway) uses a different jet for high speed than low speed and one could be clogged. Maybe run some sea foam and see if that will clear things up. Just a few things I would try, no mechanic, but a great jimmy rigger, LOL. Now you have great confidence in my knowledge

[83walleye]

Fuel pump. Go on hsolist and get a new one for $15. Nothing to it...

[Fishin4Life]

83walleye, where are the fuel pumps in these small motors, I thought they were gravity/pressure/something non-mechanically supplied by fuel? Always looking to learn new things.

[Rost]

I just talked to him again and he said it happens at all speeds now. Both trolling and WOT.

[harvey lee]

I have a motor about the same.Last year I was having about the same problems they are.I tried carb cleaner,new fuel line,bulb,adjusting carb and I cant remember what else.I then also used some sta-bil in the gas.It would not run right or at all.

So,I took it to a Johnson dealer and told them my problem.2 weeks later they called me and told me the motor was done.I went to pick the boat up and asked them what the problem was.He stated that when they took the motor off the boat and put it in thier tank it ran fine.They then took my gas line and hooked it up to the motor in thier tank and it would not run.

I had a small amount of moisture in my tank so it wouldnt run properly.150.00 later I was on my way with new gas in the tank.They also tuned it up and it has never ran so good.I'am now very carefull with keeping the gas tank full,no condensation.

I dont know if its the same problem,but it sure sounds like it.I would dump out all your old gas and try a new tank full.If it works it will be a cheap fix.I would buy the gas at another station.When my outboard was acting up so was my 4-wheeler and when I changed gas stations my 4 wheelers problem went away.

[Surface Tension]

Inside the gas tank is a tube with a brass end and screen. That tube goes from the fitting on the tank and lays on the bottom. If that tube is rotted it'll suck air. If you can squeeze the primer bulb up and not feel or hear air then that tube is probably OK.

Next thing to look at is the fuel line and bulb. If theres a loose connection or a crack in the hose or bulb the fuel pump will again suck air.

If that all checks out take the cover off the engine and inspect those fuel lines and connections.

Next, replace the diaphragms in the fuel pump.

[Rost]

Great advise guys. I told him about Harvey's boat. He replaced the fuel with fresh and added seafoam. He went out tonight and still no go. Tomorrow I'll tell him about your idea surface tension.

Thanks again everyone!

[marine_man]

What happens to the primer bulb after he first gets it started?

Have him prime the bulb to it's firm, start them motor, and let it run until it dies. After it dies, check to see what the primer bulb is like... is it flat? Is it empty? If so, I'd guess it's probably a fuel pump problem. As someone else said.. they're pretty easy to do yourself if you have a little mechancial apptitude.

marine_man