Have a 1982 OMC I/O, 2.5L, model # 252FTHRCNC, serial # J740693. Just replaced the plugs, plug wires, coil, points, condenser, rotor, distributor cap, and thermostat due to some starting and overheating problems. It starts and runs great when cold. Dwell, timing and WOT are all on spec. Can run it hard for an hour or so and it will run great and start fine. Then all of a sudden it gets hard to start. If I pump the gas a little, it will start but then coughs and spits some, idles rough and dies when I put it in gear.
Also, if I can get it started it will run good with the throttle up but as soon as I idle it and put it in gear it dies. Another thing that seems strange is that if it starts, at idle, the rpm will move around between 600 to 1100 and back, on its own. When it is cool it idles smoothly at 600 rpm.
If it cools for 15 minutes or so it will start and run good again for a while. The last trip in it started to run rough even at 3000 rpm, I had never noticed that before. Usually, if it ran, it ran good. Had to paddle it in the no wake zone as it kept dying at idle and/or shifting.
I did have some tools with me this last time and it had spark (at least with this kind of a spark tester Search: 25227 | Ignition Tester | AutoZone.com
) and the dwell and timing was OK. Engine temperature seems to be OK at least according to the gauge. The starter always turns the engine over OK. I can?t seem to duplicate this problem when running it on the muffs, it?s only an issue after it runs hard for an hour or so.
Any suggestions? What should I be checking when it does this to help troubleshoot the problem? Thanks.
Also, if I can get it started it will run good with the throttle up but as soon as I idle it and put it in gear it dies. Another thing that seems strange is that if it starts, at idle, the rpm will move around between 600 to 1100 and back, on its own. When it is cool it idles smoothly at 600 rpm.
If it cools for 15 minutes or so it will start and run good again for a while. The last trip in it started to run rough even at 3000 rpm, I had never noticed that before. Usually, if it ran, it ran good. Had to paddle it in the no wake zone as it kept dying at idle and/or shifting.
I did have some tools with me this last time and it had spark (at least with this kind of a spark tester Search: 25227 | Ignition Tester | AutoZone.com
) and the dwell and timing was OK. Engine temperature seems to be OK at least according to the gauge. The starter always turns the engine over OK. I can?t seem to duplicate this problem when running it on the muffs, it?s only an issue after it runs hard for an hour or so.
Any suggestions? What should I be checking when it does this to help troubleshoot the problem? Thanks.