#3 cylinder problem

[racingchuck]

I have a 1990 arriva with a 150hp Force outboard, cylinder #3 is way over fueled, when removing the spark plug and turning the engine over there is tons of fuel coming out, I have checked the float in the middle carb, its fine, by-passed the elec choke solenoid to the middle carb, even by-passed the primary fuel line on the middle carb, so that it has no fuel supply, BUT #3 cylinder still has tons of fuel coming out of it, compression on all cylinders is 110 to 120 even #3, so anyone have any ideas for me, Im a bit confused at this point as to how #3 is getting any fuel, much less how much it is being over fueled...Thanks

 

[Frank Acampora]

Re: #3 cylinder problem

I have not worked on those engines specifically but I think the 5 cylinder has two fuel pumps. If one is activated by cylinder #3 and if the diaphragm is broken, the pressure from the other pump will force fuel back through the pump port(s) into the cylinder crankcase and it will be pumped up into the head by piston action.

So, check all fuel lines and all fuel pumps.

 

[jerryjerry05]

Re: #3 cylinder problem

Rebuild the pumps.The diaphrams could be bad or the valves gone.
Ethanol is messing with lots of stuff!! J

 

[racingchuck]

Re: #3 cylinder problem

Ok guys Im going to check into the thought of a bad fuel pump, or bad diaphram, I was thinking that with 5 cylinders, and 3 carbs that the top carb fueled #1 & #2 cyl. , the middle carb fueled #3, and the bottom carb fueled #4 & #5, but Im guessing that passed the reeds in the intake/eng their must be another way for #3 to get fuel, a bad diaphram in a 2nd pump would over fuel, I can see that, just not understanding how #3 is getting all this fuel, and all others are ok, seriously I have removed the middle carb, turned the engine over, and it still looks like a water hose of fuel coming out of #3, burnt 5gal of fuel on the lake in less than 5min