johnson 100hp fuel problems, i think?

[mark31019]

I've got a 1971 johnson 100hp moat motor. I can pump up the fuel bulb tight and it'll crank and run for about 100 yards and then just shut off, I can pump the bulb again and it'll crank run and do the same thing. If I just let it sit there and idle or run at a very slow speed it will run a little longer but still cut off. sounds to me it's the fuel pump. i do know the the fuel system is a suction system and not pressurized system, any ideas before i spend the time and money replacing the fuel pump? The fuel bulb is good because i just replaced it and i check the fuel line and can't find any cuts. any help would be great. thanks.

 

[oldboat1]

Re: johnson 100hp fuel problems, i think?

If you can keep the engine running by pumping the bulb, you may have a fuel pump problem. Start the testing process with absolutely fresh fuel and oil, and with oil in the right mix (50:1 for your Johnson). If you have fresh fuel and pumping the bulb doesn't keep it running, the next best guess would be carburetor problems (dirty or plugged jets).