RPM fluctuating

[LubeDude]

I have a 1987 Merc 150 that has had everything rodone this summer but rebuilding the engine. Compresion is 120 all the way accross + or - a # or two.<br /><br />The problem now is that at WOT It runs flawlessly. but at any intermitent speed just cruising along, every 15 seconds or so it will change RPMs by about 1-200. Goes up, then 15 seconds later goes down, then up then down. Whats up with that??? It does it at Idle also, goes from about 7-800 RPMs to about 9-1,000.<br /><br />When it is Idling at 1,000, it will take off fine with no problems, when it is at 750-800, it will not take off slowly, I have to hammer it to get it to take off and then it stutters a couple times.

 

[KCLOST]

Re: RPM fluctuating

If it does this after warm up, I'm suspecting the reeds...

 

[KCLOST]

Re: RPM fluctuating

Did you ever check those out??? <br /><br />I assume you have good spark, and your throttle linkage is tight?

 

[LubeDude]

Re: RPM fluctuating

So far I think thats the only thing I havnt done, and Im going to do that next spring.

 

[ronmold]

Re: RPM fluctuating

Check those bleed hoses. My '86 had 2 of them split at the jugs but away from you so you couldn't see the cracks. Motor idled rough.