87' 4.3L OMC will run but will not idle low enough to go into gear without dying

[Selmo]

We just received ( from a relative) a 1987 OMC 4.3L 6cly GM (432APWXS) that had not run for two years. After a little work, it does start and run, but will not idle and go into gear with out dying. It will run at 800rpms OK but anything lower it will die. So it never gets into gear with out dying. It doesn't sputter and die, as the throttle gets almost to neutral and starts to go into the neutral position it dies. It will start right back up, but will aways die when you put into neutral. We have only run the boat on land with muffs. Can not put the boat into the water if you can get it into gear. Is this a shift interruptor out of adjustment, sticking shift cable, or is this a carburetor problem.

 

[Gilded_Splinters]

I don't understand something....

It starts and runs. That's not happening in neutral? Did you mean to say that when you attempt to shift into forward it stalls?

That aside, it does sound shift interrupter related. Also, you don't want to shift or try to shift at such high RPMs. The ESA won't really allow it and it will take tons of effort to do so and then you'll think your cable is bad, which it may be anyway.

The engine should be running at a much lower idle in order for things to work smoothly. 600 in neutral, and about 550 in gear.

 

[Selmo]

I cannot get it to idle down below 800rpms without it dying. Can never get to idle speed to shift it into gear without it dying. Not ever getting it to idle to try to put in gear without it dying. Once the throttle gets to almost to neutral it dies, at around 800rpms. Just stops running.

 

[bruceb58]

How old is the fuel you are using?

 

[Selmo]

Fresh fuel , drained the tank put in fresh fuel. Changed fuel/water separator filter. Cleaned filter in carb. Cleaned fuel lines and fitting. Have not messed with carb or carb setting, since it started. The gear is in neutral, using the throttle, the boat starts and runs,. As you pull back on the throttle towards idle, at about 800rpms the motor stops running, never getting slow enough to idle and allowing you to shift into forward or reverse. It runs well at 800rpms but any slower and it dies. Will not start in neutral, have to use throttle and give it a little gas to start, A friend said to run a tank of gas through the carb and see if that helps, since it has not run in a while. That might clear some the gunk out, allowing it to idle. Or should low idle screw be adjusted. First I should look at shift interrupter switch and see if it is out of whack. Before messing with carb.

 

[bruceb58]

If the ESA was causing this, you wouldn't be able to run at all. You can always unplug it to make sure but I doubt it
s the issue.

Might just need a carb rebuild.