115 has problems with idle thru 2700RPM

[modernrocketry]

1996 115 TurboJet

The boat ran great for 2 weeks, I took my son out wakeboarding and the boat had a really hard time getting him up on plane. Lots of smoke, etc. I assumed the water jet intake was clogged with kelp. I reversed to clear the kelp. The boat planed much more easily afterwards. Later I dove under the boat and cleared a few small pieces of kelp.

After this, the engine idles very rough and between 2000-2500RPM will die if you don?t press the choke Button every 10 seconds. Around 2700 RPM, it runs great!

I?m thinking carb problem, but would like some more educated feedback!

Thanks!

 

[ezeke]

Re: 115 has problems with idle thru 2700RPM

Reversing a turbojet drive boat won't clear anything, so it is possible that you have overheated the engine and maybe blown a head gasket.

Start your search with a compression test and spark test. Do both with all spark plugs removed.

The compression test should be done with the emegency kill lanyard pulled to supress fire.

Use a tester capable of a 3/8 minimum gap for the spark test and look for a snappy blue fire.

Check the sand filter for debris.

 

[modernrocketry]

Re: 115 has problems with idle thru 2700RPM

Here in Southern California we have Bladder Kelp that breaks free and floats on the surface. It is usually very large and very dificult to break. I have found that reversing the engine does help clear the intake. It's not perfect, but it allows me to got to calm waters and reach under.

I have solved this issue and wanted to post the results.
1. Two Harbors accidently received a bad fuel delivery of 100% ethanol. When added to their existing tank, it resulted in a 60/40 mix (40% ethanol). That only caused the engine to run very rough.
2. The fuel primer was failing and allowing air into the gas line.

I solved these by replacing all fuel lines and installing a new primer (on a TurboJet those primers are EXPENSIVE!!!)

Can't wait until the weekend!!!