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TOPIC: Motor trouble. Any thoughts?

Motor trouble. Any thoughts? 2 years 10 months ago #128703

last time I had the Hydrodyne out, I couldn't get it to plane out but once. The rpms don't get high enough (about 1500-2000 less than what it should.) I just winterized it, but before I did, I tried getting it up to the right rpms on the trailer, but it just went to 4000 and then backfired and died out. I restarted it just fine. It just won't hold at higher rpms. The fuel pump, lines, and carb are all in good shape and I cleaned them before I got it winterized. What could the problem be? (I/O Volvo Penta 80 hp)

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Re:Motor trouble. Any thoughts? 2 years 10 months ago #128704

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It can't be that you have two plug wires switched. You'd never get 4K RPMs out of a 4-cylinder if they were but I think it's definitely a spark issue. First thing to do is check the timing in case the distributor has moved a little. Next, check the spring steel on the arm of the points. If that spring breaks, it could cause the symptoms you've mentioned. Good or bad, I'd still replace the points and the condenser. Make sure the new points are set accurately. Next, you could have a bad coil that fires intermittently. I'd replace the coil as well. (If it turns out that it's not the problem, you'll always have a spare.)

If the engine backfired as you say, a cylinder (or two) fired while an exhaust valve (or two) were open. That indicates a possible cross-arcing inside the distributor, assuming the engine is in time. Check to make sure the wire to the points is not grounding out on the distributor housing. Look for small burn spots. I'd bet your problem is in the distributor somewhere. You just have to find it.

Of course, after all the above checking and parts replacement, if the problem turns out to be some kind of unexpected fuel delivery issue, I'll deny everything I wrote. (Hillary proved I can get away with it.)

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Re:Motor trouble. Any thoughts? 2 years 10 months ago #128707

Thanks for the reply! I switched over to electric ignition (hot Spark). To do that, I had to pull out the points and install the wires in the existing distributor. It has worked great up until now. I got the wires replaced and now I'm suspecting something is up with them. i had them custom made at a shop. I'll have to remove the cap and see what it looks like. Thanks for the ideas!

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