Engine quits after five minutes with cover on, runs fine with cover off

[Jemm]

Hey all;

My 96 9.9 runs fine with the cover off. It's great. When I put the cover on, it sputters and dies after about 15 minutes at idle.

If I catch it sputtering and remove the cover, it recovers and does not die.

I tried putting a fan on the cover and tried both blowing air into the engine and pulling air out of the engine. It still dies.

I've recently had the stator and power pack replaced. There is a new 50 degree thermostat.

I've set the carburetor mixture screw to factory default. I've check for kinked or pinched wires and hoses, I've tried different fuel, and a different fuel hose. I've sprayed carb cleaner into the carb.

anyone have any ideas. It would be hugely appreciated.

 

[tashasdaddy]

Re: Engine quits after five minutes with cover on, runs fine with cover off

exhaust leak into the cowl area, could be o-ring on water pump, base gasket. the engine does not like it's own exhaust. not enough oxygen.

 

[Mas]

Re: Engine quits after five minutes with cover on, runs fine with cover off

Try running the motor later in the evening with a flashlight & hood off. The light may illuminate exhaust thus pinpoint the choke!

Outboards do not like exhaust for the same reasons people do not like it.

MAS

 

[Jemm]

Re: Engine quits after five minutes with cover on, runs fine with cover off

Thank you both. I did replace the power head gasket and the (boden-see) gromet between the exhaust nub and the exhaust housing. I also replace the seal between the exhaust housing and the lower engine clamshells.

I'll try the flashlight trick tonight.