1991 Force 90 hp motor wont stay running

[fun4life]

Like the title says i have a 91 90hp force motor that wont stay running. The problem all started when we were out on the lake and we ran out of gas in the one tank so i switched to the other tank, as soon as i did that it would start for a few seconds then stall out over and over again. We got towed back to shore and headed home. When i got home i hooked up the water muffs and it started up fine, i revved it up and all seemed well. I went to another lake and it was exactly the same, run for a few seconds and die.

I was unaware that i was supposed to run the motor with the vent open and i havent had a chance to test that out yet but i wondering if i may have damaged something running like that? I pulled the fuel pump and the diaphragm doesnt appear to be damaged and builds pressure.

Any help would be appreciated cause im stumped

 

[NYBo]

Re: 1991 Force 90 hp motor wont stay running

I was unaware that i was supposed to run the motor with the vent open and i havent had a chance to test that out yet but i wondering if i may have damaged something running like that? I pulled the fuel pump and the diaphragm doesnt appear to be damaged and builds pressure.

That would explain the problem. You will have to do that test and see how she runs.

 

[fun4life]

Re: 1991 Force 90 hp motor wont stay running

Out of curiosity why does it run fine out of the water? And also i ran it a few times in the water with the vent closed without issues, thats why im curious if i damaged something.

 

[fun4life]

Re: 1991 Force 90 hp motor wont stay running

Well i did a quick compression test and found 2 cylinders @110psi and 1 @30psi. Guess im gonna have to do a tear down.

 

[NYBo]

Re: 1991 Force 90 hp motor wont stay running

Ouch. So it's not just fuel starvation from the closed vent.

The reason it may have run fine out of the water is that there's no load on the motor so it doesn't require a lot of fuel. There was probably enough leakage in the vent's gasket to allow enough fuel to flow under a no[load condition.