Engine Warms up and wont stay running

[tedurocher]

Hi all,
I'm going crazy and hope you all can help.

I have a 1985 32 Bridge sedan with 235HP 318's. The guys I bought the boat from years ago replaced the distributors so I have no points or ballast resistor.

I've having an issue with the engines warning up and then shutting off. I eventually linked that to having the wrong coils, external vs internal restitance.

The problem I am having now is my starboard engine will run for about 20 minutes and shut off.

I suspected moisture in the distributor cap and have been pulling the cap as soon as it stalls and spraying WD40. I can restart the engine 2 or 3 times like this but the engine will only run for a minute or two before shutting back down. After the 2nd or 3rd time I have to wait between 10 and 20 minutes before it will restart and it will only run for about a minute or so. If I let the engine completely cool down it will start and run for 10 to 20 minutes before shutting off again.

Ideas? Thoughts?

thanks,
Todd

[tedurocher]

more details

here are the numbers on the tag on the side of my distributor

Chrysler 2444986
I BM4109AS 103

[Tuggle]

Have you checked your fuel filters?

[tedurocher]

Have you checked your fuel filters?

no I havent but I will.

[Busia]

Check your fuel and spark. Remove the flame arrestor and pump the throttle. Does the accelerator pump squirt gas? Try it before you start it to see how it works. Try your spark. Remove the coil wire from the center of the distributor and place it 1/4 inch from the block or some grounded metal part. Crank it over and you should see big sparks. Do you have tach or sync wires to the coil? Take them off, you don't need them and you don't want a bad gauge to trick you. My guess is you lose ignition. If you don't get a spark the next thing to check is do you have the proper voltage to the coil. Good luck.

[Fastjeff]

That's the ticket! You should have a nice BLUE (not orange) spark that jumps at least 3/8 inch. If you don't, put a voltmeter on the '+' terminal of the coil (ignition ON) and see what voltage is there.

Jeff

[tedurocher]

thank you all for the good suggestions.

coil is new, it could still be bad though right?

I can pump fuel, including tried using starting fluid with no restart until it sits fir 10 to 20 minutes.

it's like something happens when the engine warms up that is killing the spark. Once it cools down a bit it will fire right up and run for a short time and studder and then stall

[bcassedy]

Not being a "gearhead" but more of a shade tree mechanic, I wanted to ask... (and if the fact that Todd said POs replaced the distributor may make this a silly question.....) ... I had a somewhat similar instance occur on first the port engine and then a couple of years later on the startboard (run a while then die and not start until "something" had time to cool down....)...

Could there be a problem with the ECM (electronic control module)? I was advised by a true mechanic to replace that and it cured the issue on the port engine. When the same problem occurred on the starboard engine happened, I replaced its ECM and issue was resolved.

Bill

[tedurocher]

in regard to the ECM . . . . what does it look like?

my boat is a 1985, would it be like an electronics module inside the distributor?

[jralbert]

Another non-gear-head response based on observations here over a long time: This seems heat related. Something heating up and failing. What's likely culprit? Is vapor lock an issue?