5.7 1987 OMC shuts off at Low RPM

[Lou C]

if it drops low enough to starve the igition system yes.

 

[Scott Danforth]

All of sudden looks like my volts have been dropping aswell, could that make stalling at low rpm ?

could be part of the problem, however it wouldnt be the main cause

 

[Lou C]

For example on boats with lousy corroded battery cables you can get an engine stumble just from using the trim system, it draws enough current that it can drop your system voltage enough to starve the ignition system. I had this on mine when I first bought it. Dumped all the crappy wiring when I installed a dual battery system about 15 years ago.

 

[Nick_1987 5.7 OMC]

For example on boats with lousy corroded battery cables you can get an engine stumble just from using the trim system, it draws enough current that it can drop your system voltage enough to starve the ignition system. I had this on mine when I first bought it. Dumped all the crappy wiring when I installed a dual battery system about 15 years ago.

So maybe my issue could be a combination of this and a dirty carb. I was at the boat yesterday and I tightened the belt and everything is back to normal with the alternator, 14.4 volts at idle. Now the carb. I threw in some seafoam and after I burn this tank of gas, if the problem is not fixed I will clean the bar myself. Where can I find instructions and kits for this?

 

[Lou C]

You have a Rochester Quadrajet. There's a lot to know, its a fairly complex carb.
Resources:

Cliffs High Performance Quadrajets – Quadrajet Rebuild Kits, Cabruretor Parts, Quadrajet Rebuilding, Quadrajet Parts, Bushing Kits, Carb Tuning

cliffshighperformance.com

Mike's Carburetor Parts

www.carburetor-parts.com

the cleaning is the main thing especially the ilde air tubes. read up on this.
just removing the air horn is a bit tricky, you have to knock the roll pin for the accel pump lever in just far enough to allow it to come apart and disconnect the choke linkage on the other side. then it will come off, be careful with the metering rods.

 

[Sattech200]

I'm having the exact same issue! (1985 25' Rinker 5.7l OMC) It almost sounds like the engine is dying right before it tries to shift into gear like the kill is triggering just a tad to early. I have one run on a rebuilt engine last summer with new everything and the distributor has an electronic drop in conversion done. boat ran great before this. ran great launching from the dock and 10 min drive upriver to the dock but trying to get it into the dock the problems started. then tried going out to the lake and fought it all the way there and back. I'm not sure I could get it back to the dock at this point. It does seem like its a little harder to shift then it should be though. I'm going to print this out and head back down to the boat and see if I can figure anything out.

 

[Lou C]

Your problem might be different in that the ESA is being activated when it should not be. It should only activate (lower the idle rpm) when shifting from in-gear to neutral to allow the clutch dogs to release. Never when going into gear.