I am trying to help my nephew out. He just bought a boat with an 89 70HP Evinrude motor that wont idle. It will run if you throttle up the fast start but it wont idle at all.

Here is what is known about the motor - it had oil injection but it was taken off. I have no idea if this was done correctly or if the removal technique used could be part of the problem. The carbs are clean - I pulled them and cleaned them myself. Compression is from top cylinder to bottom 110,95,92. All cylinders are getting spark.

Any direction on trouble shooting this issue is GREATLY appreciated. Thanks

Compression is a little suspect. Remove spark plugs and take a pin light and look into the cyl. See if you can see any scoring. If not then decarbonize the motor real good and see what happens.

Compression was tested with a loaner tester from O'Rielly's so I can not attest to its accuracy but it was consistent.

How do I "decabonize" the motor?

Did you check the reeds? Have seen the enrichment solenoid leak by or the arm be turned the wrong direction causing a rich condition. These motors bad about sticking the rings on the bottom cylinders. Is it spitting fuel?

How was the idel before you rebuilt he carbs?

Sometimes soaking isnt enough.

I agree with above, decarb it and recheck compression.

When he got the boat it would not idle. The carbs did not appear to be dirty when I cleaned them. After the cleaning there was no change in operation of the motor. It runs strong when throttled up but wont idle at all.

**EDIT**

The spark plugs were black. How do you "decarbonize"?

Reeds visually looked intact and ok. Solenoid arm was pointed towards the opposite end of the solenoid and not away from it which should be correct? No fuel leaking from the solenoid either.

Sounds like your getting too much fuel, has to come from carbs, fuel pump or enrichment solenoid. You have to pull the out hoses, pump the bulb to check the solenoid. Could you have some old bad fuel? I like to pull the spark-plugs and spray Creep by Sea Foam in each cylinder and let set over night. Then add Sea Foam to the fuel.

OMC also used to make a spray can you took the air box off and sprayed it into the carbs while the motor was running for a while when the can was empty you shut the motor off for something like 3-12 hours and then start it up again. It got alot of carbon out the first time we did it. I dont know if they still make it thought.

matt

Looks like it will be going to the shop! Awesome. Will update the post when a real meachanic reaches a verdict!