'87 OMC 3.0L chevy I/O it runs great then suddenly dies

jerrybel

Recruit
Joined
Oct 10, 2003
Messages
4
My '87 OMC 3.0L chevy I/O is running great EXCEPT after running for about 45 min continuously it will all of a sudden stall out, it totally loses ignition. Wait about a minute and will start right up and run for about 5 minutes and die again. This happens at WOT and idle. I take it home and will run for over an hour and never kill. But take it out next day and will run for 30-45 minutes and kill. It had electronic ignition before but doesn't last more than a year before burning up. Last point system lasted over 3 years before i replaced them.The reason for replacing them was because of the above problem.I ruled out fuel problems.<br />It has a brand new:<br />- coil<br />- points<br />- plugs & wires <br />- battery.
 

loadnet

Petty Officer 1st Class
Joined
Aug 27, 2003
Messages
225
Re: '87 OMC 3.0L chevy I/O it runs great then suddenly dies

That sounds a little weird?<br /><br />Runs fine at home but not on the water?<br />Are you SURE this is an ignition problem?<br /><br />What tests have you performed on the water to determine no ignition? at the moment the problem occurs?<br /><br />Thanks.
 

jerrybel

Recruit
Joined
Oct 10, 2003
Messages
4
Re: '87 OMC 3.0L chevy I/O it runs great then suddenly dies

As soon as engine kills, i pull a plug and check for spark.
 

andrewgroup

Petty Officer 2nd Class
Joined
Aug 23, 2003
Messages
115
Re: '87 OMC 3.0L chevy I/O it runs great then suddenly dies

I'll repeat myself only to hear myself talk again, because I have to remember to take this advice when I'm faced with adversity. Barring major hardware failures, Internal combustions engines are simple and require 3 things. Fuel, Spark and Air. Remembering this will allow you to use a few simple procedures to confirm the existance of all three.<br /><br />Listing the new components is not a troubleshooting procedure. Your best time to determine what is happening is that minute you waited before the engine started again. A timing light on a plug wire can confirm spark, a shot of starting fluid can confirm no fuel, I've used starting fluid to get back to dock many years ago.<br /><br />I also recommend you do some good documentation of some diagnostic points when the motor is running properly.<br /><br />This could end up being a bad electrical connection on a critical voltage point such as a fuse or junction point. Really take the time to investigate these connections and document the voltage levels on them when all is working good. As things heat up electrical parts expands and change characteristics. I recommend the elimination of shutdown circuits like safety switches, Shift Assistance circuits. With the electrical diagrams of your unit, plus searching for posts on this board you will find info to bypass these circuits.
 
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