RPM's going up and down

[CAPT.KEITH]

I need a expert,
I have a 1987 sea ray 340 in it is two MIE 340's My Starboard engine rpms are jumping about every 10 to 20 seconds when running above 2600 rpm,MOSTLY. I need 3200 to plane.
I switch to run off the other tank and was able to run at wot for about 15 min. b-4 I had to return to slip so I went out the next day and it ran about ten min. at wot b-4 the rpm's began to jump around.At this point it early Sep. and the gas is from last season.
tuned last season with wire's,coil,plugs,ignition modular,reman carb.
That being said the reman was no good till this season when I got the right one working all looks good but why is the engine jumping with my rpm's.
Just did a compression test all at 135 psi. all plugs except one looked the same the odd one at the electro was a light tan color ant electro was dry?

Thanks for your time on this matter,Capt Keith

 

[rma153]

Re: RPM's going up and down

Do you have ignition sensors in your distributors? - they can start acting up and can eventually cause no spark

 

[CAPT.KEITH]

Re: RPM's going up and down

Hey thanks for your thought's RMA153.
Yes I do and they where replaced last Aug of 06. I've read that some people have gone threw several in a short period of time. And then I lost that thread.The one's that I took off were the older style, they last at least six year's.
Have you heard of a black grease ( from radio shack ) to coat parts to keep them cooler when touching warm plates such as inside the dist.?
Would you be able to tell if the exhaust elbows are supposed to be cool to touch or hot after running.
I'm thinking about throwing on new coil and cap and do that thunderbolt IV test to see if I can narrow it down some more I only have till the end of OCT.
Thanks,again as you can tell this my first post and your comments I believe to be on the right track!

Capt Keith

 

[CAPT.KEITH]

Re: RPM's going up and down

Just for FYI, after compression test one s/p turned up clean, restarted engine and it turns out that I had one s/p wire that was not clicked on the plug.
Thanks for you time everyone.
Captain Keith