curious problem with rough running

[gerg1962]

Hello,

I have a 26' Fiberform boat with a 1988 OMC King Cobra I/O (460 Ford).

I recently replaced the carburetor and the motor was running fine. The boat had been sitting for a month or so and I went to run it for awhile with the ear flaps on the outdrive.

It started right up and was idling fine. When I tried to rev it up a little bit it suddenly lost power and the tachometer was reading 100-200 rpm and I could not get the rpms up, the engine was running very roughly. When I backed off the throttle the idle was fine although the tachometer was still reading 100-200RPM I would say it reality it was running more about 800rpm.

Curiously, at idle when I engaged the drive in forward, the engine rpm on the tach returned to 800rpm or so and I was able to rev it up without issue seemed to be running fine. As soon as I disengaged the drive, same problem as before, tach needle dropped and it would not run past idle?

This is a new one on me.

Any ideas out there?

Thanks,

Craig

 

[Bondo]

Re: curious problem with rough running

Ayuh,.... Look for a bad, broken, or loose wirin' for the tach....

It feeds off the (-) on the coil, 'n could be sporadically groundin' out the ignition...

 

[SteelBlack]

Re: curious problem with rough running

Could it be the shift interupter is not set properly? Not familure with how the system works and not sure changing the carb even effects that. But I seem to keep running into threads that talk about motors missing and the interupter is the issue. Just my .02.

 

[jerryjerry05]

Re: curious problem with rough running

Like steel said, the shift interupt switch.
OR.Possible the cable's binding and needs replacing.

 

[gerg1962]

Re: curious problem with rough running

Okay, those are some good ideas I will delve into.

Not sure how the shift interupter interplays with the ignition but I will consult the manual.

I gather that it would cause the engine not to start if the drive is engaged, and if it is in neutral and the interupter is partly engaged it might be tfighting to shut the engine down?

The curious thing is that is runs fine at idle with the shifter in neutral although the tach is giving a screwed up reading...

Thanks,

Craig

 

[Reinell-BRXL-191]

Re: curious problem with rough running

Stuck closed choke?

 

[bruceb58]

Re: curious problem with rough running

To see if its the ESA causing the issue, just unplug the ESA harness and see if the problem goes away.