Engine running at half power

[chuck71449]

I have A 1977 chrysler 135 magnapower I replaced the sterring system and took the boat out for a run about 20 mins in the engine seemed to cut back to half power I have great spark at plugs 120 on compression my magneto has cracks coming from each contact ive cleaned the carbs replaced spark plugs not sure what to do. Ive tried to move timing advance but it makes no difference it the way the engine runs i need some assistance please. it idles great and runs great with the muffs on but under a load it just dosnt have the power any ideas?

 

[jerryjerry05]

Re: Engine running at half power

Check the fuel pump diaphram??
Any fueline inline connectors?The can leak and suck air.
The fuel tank vent clogged?
Clean the carbs.

 

[chuck71449]

Re: Engine running at half power

I will give that a try we changed fuel filter and replaced the clamps made sure no air leak I havent checked the diph on fuel pump though. will check fuel pump diph and clean carbs again and see if that works let you know how it goes. Thanks.

 

[chuck71449]

Re: Engine running at half power

Ok new probem the fuel pump was sucking air and diph was bad. I had puled the flywheel before I posted this tread t see if the ky was sheared well i didnt get the flywheel tight and woun up shearing it.

my problem is before it sheared the engine was running great I replaced key and reistalled the fywheel and now ony have one coil fireing any ideas?