Mariner 4hp lost power after hitting rock

[jokajo99]

I have a 4hp mariner that was running great untill I hit a rock or something and then when I ran full throttle i had practically no power. Any ideas? Any responses would be appreciated.

 

[sschefer]

Re: Mariner 4hp lost power after hitting rock

I have a 4hp mariner that was running great untill I hit a rock or something and then when I ran full throttle i had practically no power. Any ideas? Any responses would be appreciated.

Not sure if you have a shear pin or a rubber hub in that prop but I'd bet thats the problem since that's the design. IE.. hit a rock, shear the pin or spin the hub and save the drive shaft or crank.

Pull the prop off and take a look.

 

[CharlieB]

Re: Mariner 4hp lost power after hitting rock

After you check that prop, if it checks out good, Too hard a 'bump' could have sheared the flywheel key causing the timing to advance. Does it still idle at the same speed as before? Advanced timing should raise idle speed.

Check WOT Timing with a timing light, if it has changed THEN pull the flywheel and check for a sheared key.

 

[jokajo99]

Re: Mariner 4hp lost power after hitting rock

It is not a thru hub exhaust.I pulled the unit out today and saw no sheered tines or any metal pieces in the case.The oil was clean and looked like new.I do not have a timing light but may be able to get one.Any other advice?

 

[CharlieB]

Re: Mariner 4hp lost power after hitting rock

Remove the spark plug, use a flashlight if needed to look into the hole while turning the motor over slowly by. Bring the piston up to Top Dead Center (TDC) and leave it there.

Check the timing marks on the flywheel, does the TDC mark line up with the pointer?

If not, then remove the flywheel and the sheared key, order a new key from your dealer and reinstall the flywheel.