Greetings all. This is my first post.
I just bought a 1975 20' center console Grady with a 1998 Johnson 150 Ocean Runner FICHT.
On the test-ride, it had a very noticable hesitation at idle, but it never stalled. It JUMPED up to plane, and ran GREAT at higher RPM's, with no hesitation or vibration at all. Ran straight up to 35 MPH at 5,500 RPM's with no issues.
Here are my questions:
1. At idle, the engine has seriously varying RPM's. It will start, then drop RPM's, then recover, then drop again, at various intervals. Constantly sounds like it's about to stall. It does NOT have a lean pop that I can hear, but maybe it's muffled by the water and cowling? I pulled the plugs, cleaned them, (somewhat sooty) and indexed them, but no effect.
WHAT IS THE LIKELEY CAUSE OF THE ERRATIC RPM'S AT IDLE?
2. Due to the sooty plugs, I'd like to decarbonize this engine.
IS THIS RECOMMENDED? WHAT PRODUCT/METHOD IS BEST WITH THESE ENGINES? I don't want to mess up anything
3. I've heard I can get a program that can connect a laptop to the engine's computer to see what's going on. IS THIS AVAILABLE TO THE PUBLIC? IF SO, HOW MUCH DOES IT COST, AND WHERE CAN I GET IT?
Unfortunately, I don't have a lot of money, so I have to try and fix this problem myself, if possible.
THANKS in advance for any help you can give.
Oh, and one more thing... I notice that the guy uses some cheap, generic oil. That probably explains some of the soot.
I believe the E-tecs REQUIRE the use of XD50 or XD100 oil.
DO FICHT ENGINES REQUIRE THE XD OILS, OR CAN THEY USE REGULAR TCW3 OIL?