Mid 80’s E/rude V-6 150hp. Loses power after planing

[mogems-yahoo-com]

After not being winterized, this rig starts easily & runs well until I get on lane. Then it falls flat. I’m going to completely purge the fuel system this week (incl.: Dump & clean tank, flush fuel lines & pump & filter, install fresh fuel mix 45:1). Also will R&I plugs. Any othe suggestions before I button it up & test run again? Thanks, George Salomskas , mogems@yahoo.com or 856-447-3641 South New Jersey.

[fleetwin]

Well
Could be just about anything, so starting with new plugs is a good idea. Do your carbs have metal or plastic bowls? Do you have an OMC jet screwdriver? If you have metal bowls and a jet screwdriver, I would pull the high speed jets and inspect. The plastic bowls make their own debris when threading jets in and out, so you have to be extra careful during removal/installation.
You could isolate problem cylinders by removing the large plastic air box cover and injecting each throat with fuel/oil mix (from an oil squirt can) while the engine is misbehaving. The RPM should drop some when injecting a good cylinder. If there is a fuel delivery problem on a particular cylinder, the RPM will spike up for a second indicating a lean condition for that cylinder. If there is no RPM change when injecting a particular cylinder, that would indicate some other problem like ignition.
You could try pushing the key in (to prime) for a second while the engine is misbehaving, the RPM might spike back up for a second if there is a lean condition in a cylinder(s). Unfortunately, this method can cause confusion because you are richening up good cylinders while supplying needed fuel to the lean cylinder(s).
Sounds like you are going to check your fuel system, which is the place to start. Do you have a spin on water separator filter, that might have water in it. Your fuel system may have an air leak/restriction causing a lean condition at high speeds as well. You could try pumping your squeeze primer bulb while the engine is misbehaving as well, an RPM increase would indicate an air leak/restriction/filter, or fuel pump problems.
Sorry I can’t give you any specific advice, except to say inspect the simple stuff to avoid getting buried in confusion.
Let us know if we can be more help….D

[jerry-ahrens]

Fleetwin has given you some good advice. A couple other things I can throw in here are 1. You may have a power pack failing on either the left or right bank. Your engine has two of these. These motors will run pretty good this way till you try to get on plane, then bog down. The pack can malfunction, then start working again. 2. You may have a float needle stuck in one of the carburetors. Again the motor will run pretty good till you try to get on plane. Use the squirt bottle method that Don has suggested above to check.
Keep in mind that if you have a plugged or obstructed carburetor, you WILL do engine damage if you continue to run it this way, because you are also starving the engine of oil. Just something to keep in mind to avoid a blown powerhead. Hope this helps!

[Anonymous]

I was gonna say "try detaching it from the trailer and it might plane better" but looks like them other guys might be more helpful…..

Best,
T2

[fleetwin]

Jerry is right about the powerpacks, will run pretty good on three cylinders at lower speeds….You will need a spark tester to analyze further. One bad pack would kill one bank of cylinders (either port or stbd). Let us know if you find one bank of cylinders is not sparking, then we can proceed with some basic ignition tests….

[mogems-yahoo-com]

Great info guys. Hey T2, nyuk nyuk nyuk! Thanks to all of my friends @ AOMCI. We belong to the most super intelligent & very cool club.

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