88 Mercury Black max v6 lost 1k rpm from top end

[waveskimmer]

Black max v135 lost about 1k rpm on the top end, and comes on plane poorly. Did a high speed shutdown to read the plugs, all were pretty close to dry. Compression checks out, 120 psi on each cylinder. This all started with a fill up at my local marina with bad gas. Soaked the carbs internally with seafoam, got a bit better. Now running with e-free 90 octane. Going to check the fuel pressure tomorrow. Seems quite obviously to be fuel starvation. Inline fuel filter in front of the pump stays full with no bubbles at all RPMs.

Any ideas?

Thanks!

[David - WI]

Are you sure you don't have a bunch of water in the tank from the bad fillup?

[waveskimmer]

Sorry, should have mentioned that I'm running on an external tank to eliminate that possibility.

[David - WI]

Still... water in the carbs, water in the filter?

[waveskimmer]

Was hoping the seafoam soak would take care of that, but I do have gasket kits on the way if it comes down to carb teardown. I'll drain the float bowls via the main jets to get a look. Inline filter looks good, just replaced the cartridge.

[KIRCHNER]

MAke sure you have 14v+ at the motor, @ 1500 r p m.

[skialot2]

You have a fuel restriction somewhere past the filter. Pull the plugs for the main jets from the float bowls. pump the primer to flush the crap from the float bowls and make sure fuel flows freely. You may have to one carb at a time. You might want to spray carb cleaner directly in the main jets with the little straw that comes with the cleaner. Then blow the jets out with air. Use the straw from the carb cleaner. Stick it in the end of your blower and pinch it with your fingers. It will seal enough to blow the crap out of your jets. If that doesn't work, take your carbs off and clean them thoroughly. Good luck

[waveskimmer]

You have a fuel restriction somewhere past the filter. Pull the plugs for the main jets from the float bowls. pump the primer to flush the crap from the float bowls and make sure fuel flows freely. You may have to one carb at a time. You might want to spray carb cleaner directly in the main jets with the little straw that comes with the cleaner. Then blow the jets out with air. Use the straw from the carb cleaner. Stick it in the end of your blower and pinch it with your fingers. It will seal enough to blow the crap out of your jets. If that doesn't work, take your carbs off and clean them thoroughly. Good luck

Yup definitely fuel restriction. The fuel pump was due for a rebuild, did that, no change. Pulled the top carb and noticed the butterflys over rotate past 90deg at stop position. Probably not much to do with the current problem, but... I'm probably going to drop the float level a bit as well to try and richen things up.