1988 johnson 88spl sudden drop in rpm

[Mel85CJ]

We have an issue with our 1988 88spl (we just got and installed this motor)
We ran it friday and sat am with no issue, it gets up to 5000rpm with the 13 pitch prop we just put on it. However, yesterday afternoon it started running rough. My husband went to check it out and foud the plug wires were old and came apart. This am he got new wires from the local marina and put them on. The boat will not get above 2500 rpm and also idles very low (like 500rpm) my husband has also put in new plugs and even removed the carbs and cleaned them and reinstalled..... any ideas on other things to look at? This has taken away the day today and my (pretty mechanically inclined) husband is just out of ideas...

Please help

Thanks
Melanie

 

[Daviet]

Re: 1988 johnson 88spl sudden drop in rpm

A couple of thoughts, what is the compression numbers, have you checked the spark on all cylinders?

 

[Mel85CJ]

Re: 1988 johnson 88spl sudden drop in rpm

We got spark on all cylinders, cant check compression since the compression guage is. 2 hrs away at home

 

[Daviet]

Re: 1988 johnson 88spl sudden drop in rpm

Spark is good. Be careful doing this, remove one plug wire at a time and see if you have a cylinder that is not firing. Like I said be careful, you can get quite a jolt if you get shocked. If you find a cylinder that removing the plug wire does not cause an RPM drop, remove the plug and see what it looks like.
As your husband probably knows, timed spark, compression and fuel is all you need to make your engine run. You are missing something.

 

[Mel85CJ]

Re: 1988 johnson 88spl sudden drop in rpm

We are thinking now it is a bushing with the flywheel and timing. We are gonna try to pull the flywheel this am.