9.5 hp surging

[starcraft69a]

I have a 1965 9.5 and under full throttle it surges in power. so I pulled the cover off to watch it run under full throttle and it runs fine no surge and runs faster. If i put the cover back on it slows down and will surge. Is this a fule mix problem os there anything I can do befor rebuilding the carb? thanks in advance.

 

[mchin]

Re: 9.5 hp surging

you're motor maybe choking on it's own exhaust fumes. There's a oval gasket that is seals the lower cowls. Here's the part from the BRP site, the part should be the same for Evinrude as well as Johnson.

0312211
SEAL,Exhaust housing

By the way it's not easy to get to this part, there's a sequence to taking off the cowls and lower unit.

Ya might wanna get a manual.

 

[Rick.]

Re: 9.5 hp surging

I agree. It's probably exhaust leaking into your cowl. If your running it in a barrel don't worry about it as the motor sits low and the fumes are more concentrated. If it does this on the water you will have to replace the gasket. Best of luck. Rick.

 

[tashasdaddy]

Re: 9.5 hp surging

adapter plate gasket leaking. agree with above.

 

[ezeke]

Re: 9.5 hp surging

The 9.5 can easily leak exhaust inside the engine compartment from a torn or loose exhaust relief hose #309830. Like other motors, exhaust can also leak from a bad exhaust gasket at the engine.

The most common source of exhaust leakage is from a missing impeller housing seal or from a missing or leaking shift rod boot #309631.

Exhaust leaks around the exhaust housing seals #0312211 are very rare but are sometimes caused by items such as screws being dropped into the cowl from above.

The surging that you describe could be from having the lean/rich needle adjusted incorrectly; it should be done with the cover on.