Omc 120 3000 Rpm At Full Load?

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Hey all,

I have a 1986 seaswirl open bow 16.5' 120 omc (2.3l gm engine w/ 2 jet Rochester). I picked this boat up earlier this year, and have an engine issue. Here is the problem: Running in neutral, the engine revs crisply, and hits 5000 rpm (thats when I let off). When running under load (doesn't matter how many people are in the boat), the max rpm is 3000 rpm. I have a 15.5x15 pitch prop, and a 15.5x13 pitch prop. The max rpm is the same with either prop installed. I have checked compression 145-150 psi on all 4 cylinders. Did a basic tune up: cap, rotor, plugs, wires, which had nil effect. I am a CAT diesel mechanic, and if this was a diesel, it acts like lack of fuel. I am not a gas engine guy, and have been told that it is not a fuel issue b/c it would run hot? The timing was set at 14 deg. btdc. I reset it to 4 deg. as per the valve cover spec., and this had nil effect. The distributor is new, and has mechanical advance. Please Help!!

[gonzo]

What do the sparkplugs look like? If it is running lean they will be very white

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Gonzo,

Should I check them now, or should I check them right after a full speed run? If I check them now on the trailer, the last load the engine saw was when I idled through the marina before loading. Will this change anything?

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I had another thought. The distributer has been replaced (not by me), and has been updated with an electronic ignition conversion kit. Is there any component in this ignition system that would limit the revs?

[PAR]

Your engine should be hitting 5,600 to 5,800 RPM if well tuned and propped at WOT under load.

Which ignition module do you have, the CDI or the Mallory?

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Par, maybe I misspoke. As I said before, I don't have much experience with gas engines. The distributer cap, the points have been removed and replaced with an electronic pickup. The pick-up is wired to the coil. There is an electronic component mounted to the front of the valve cover, but I don't know what it is. I can post pictures if needed.

[gonzo]

If the limiter was faulty you wouldn't be able to rev it up even with no load. Check the plugs after at least twenty minutes of whatever you max speed is.