4.3 OMC Stalls at low RPM after warm-up

[drpboston]

Hey guys,

Newbie here. Well to boats anyway.

1988 4.3L w/cobra outdrive replaced coil, points (gapped at .019)/condenser, plugs - checked dwell (30 degrees) and adjusted timing. Of course ran like a top out of water.

Dropped in, cruised nicely under load for 30 minutes then we slowed down to watch a 747 take off right over us and stalled. Started up and off we went (back to our mooring!) then when navigating mooring field would stall at low RPM. Would restart after 5 minute wait and run with throttle open, but as soon as I go to get into gear and RPMs drop, chokes and dies out. We had to be pulled to our mooring.

Is this a choke issue or do I have to adjust idle after messing with dwell and timing?

Exchangers not crazy hot, no signs of overheating, but can't tell without temp gauge because I also noticed temp gage not working now. (how can I test gauge vs sending unit vs anything else you can think of?)

Been reading the forum and seems like some really knowledgable folks here, so thanks in advance!

 

[dlplost]

Re: 4.3 OMC Stalls at low RPM after warm-up

When you did your adjustments, was the motor up to operating temp with the choke off?
Or was it cold with the choke still on?

 

[drpboston]

Re: 4.3 OMC Stalls at low RPM after warm-up

Good question. I would guess it was still relatively cold since it only idled for about 5-10 minutes out of water. Do you think I should repeat all readings and adjustments after a quick spin?

Or how long will it take to get to operating temp idling in the water?

How can I test the temp gauge vs sending unit?

 

[danond]

Re: 4.3 OMC Stalls at low RPM after warm-up

Get your temp gauge fixed so you're not guessing. Can't be certain your thermostat is operating properly if you don't have that, and overheating kills motors!

Also, an OMC service manual answers all your gauge testing questions.

 

[drpboston]

Re: 4.3 OMC Stalls at low RPM after warm-up

Went out to tinker with it today, started up, ran it at 2-3000 rpm for 3-5 minutes then throttled back to see if it would idle cold, and now even cold it won't idle. right before it stalled I checked timing and it's right on. Since I did change the points and set new dwell and timing, do I have to adjust the idle screws? It all ran fine right after the tune-up but once under load started to act funny.

Also as it comes back to idle I looked into the carb (2bbl) and saw a pooling of gas above the throttle body valves. Are these supposed to be slightly open at idle or do the floats have to be rebuilt?

Thanks!

 

[drpboston]

Re: 4.3 OMC Stalls at low RPM after warm-up

Bump - Anyone?

 

[donwon]

Re: 4.3 OMC Stalls at low RPM after warm-up

I know it is two years later but any word on what the problem was, I have a similar sounding problem?