Engine runs good without cover on, with cover runs bad

[sxm_tj]

hi

ive posted a thread before, stating the problems im having with my johnson 1978 25hp

i sorted them out, but ive got a new problem, the engine runs fine (in bucket not boat tested yet) without the top cover on at wot and stationary, but as soon as i put the cover on the rmps go a little lower and at wot the engine dies down.

to me this would seem like it is not getting enough ait or to much gas.

the high speed yet size is i think origninal, i just cleaned the carb verrry througly with profesional equipment.

what could it be?

thanks

 

[F_R]

Re: eingine tuns good wthout cover on, with cover bad

Re: eingine tuns good wthout cover on, with cover bad

Put it on a boat. Running it in a barrel it gets too much smoke sucked in under the hood, which kills it. You are sort of right, it is not getting enough air....actually oxygen. It won't run on carbon monoxide and all the other pollutants in exhaust smoke.

 

[grid]

Re: eingine tuns good wthout cover on, with cover bad

Re: eingine tuns good wthout cover on, with cover bad

Another problem I ran into with that model (and i'm certainly not discounting the advice about the CO and O2, which is quite true) was the shift interlock rod hitting the side of the cover, not allowing the magneto plate to advance completely. It was a unique problem, but cured by replacing the interlock arm, which had worn away too much for proper throw.

 

[MikDee]

Re: eingine tuns good wthout cover on, with cover bad

Re: eingine tuns good wthout cover on, with cover bad

Please don't rev your motor to full throttle in neutral, it is never good for an engine, this is just a pet peeve of mine, learned from experience. Now, maybe another possibility is there is an exhaust gasket leak from underneath into the cowl with the cover on, check it out, good luck Mike

 

[sxm_tj]

Re: Engine runs good without cover on, with cover runs bad

i wil test it as soon as possible, i thingk indeed it is the fact that all the somke gets sucked in and hardly any oxygen

being it creats a lotta smoke and the bin a hand it in has no room for ventilation, il let yall know.
thanks for all the help