1990 Johnson 120HP gas bulb keeps going flat.

[Pwa120]

i have a 1990 Johnson 120 horse. i get out on the lake the engine starts fine. however when i give it throttle the gas bulb always goes flat after about 30 seconds at full throttle but i can putt around the lake for 2030- minutes going about 5mph. I've bled the gas and just cant figure what else could be wrong. help please.

 

[imported_lorin]

Re: 1990 Johnson 120HP gas bulb keeps going flat.

What's wrong is you probably have a fuel restriction somewhere in the fuel line or in the fuel pick-up in the fuel tank. The fuel pump sucks the fuel out of the line and more fuel can't enter to take it's place so a vacuum is created in the line and the bulb collapses. Other possible causes are a bad bulb or the vent on the fuel tank is clogged or closed. You can putt around because enough gas can get by the restriction at slow speed to keep the fuel line full and so the bulb doesn't collapse.

 

[Pwa120]

Re: 1990 Johnson 120HP gas bulb keeps going flat.

do you think that a test of maybe hooking up the bulb to another small tank would be an idea. to isolate the problem? thnx Lorin

 

[tashasdaddy]

Re: 1990 Johnson 120HP gas bulb keeps going flat.

yes. check to make sure the gas line in connected correctly. the bulb has a arrow on it the arrow points toward the engine. it a common mistake.

 

[imported_lorin]

Re: 1990 Johnson 120HP gas bulb keeps going flat.

Yes, using a different fuel tank, and/or using a different fuel line and/or bulb would be the way to isolate the problem.