20HP Onan loosing fire

[Dennis 0]

I have an Onan/Linamar 20HP engine on my 89 model 520H. The engine is 8 years old.

The engine will start and run for a few minutes then quit. I've checked and the engine is loosing fire. I replaced the coil and it didn't help . I've removed the wiring harness coupler and spliced the wires thinking that the problem was in the coupler but it didn't help. I also rebuilt the fuse block that didn't help.

What would cause the engine to start and run then die and refuse to restart until it has sat long enough to get completely cold? I know something is getting hot and breaking down and would have sworn it was the coil. If the problem was one of the safety switches the tractor wouldn't turn over,right? What do I do next? :D

[WH nut 553]

Does it crank and no fire, or just plain no crank. Mine would die but fire right back up. I found a bad connection at the PTO switch. We will need a little more info if you could

[Dennis 0]

After the engine quits it will crank but has no fire(I pulled the front plug and grounded it, no spark) after it quits it might start again after it cools off but only runs for a few minutes or maybe 15 minutes the dies. something is getting hot and failing causing the engine to die. :thumbs:

[300zx 7]

Dennis, have you checked to see if there is voltage on the positive side (small post) of the coil with the key on when the tractor dies and won't start. If there isn't, I would try to jumper a wire from the positive side of the battery to that same post. (Only do this temporarily to see if it starts because you will have no fuse in the circuit). If it starts, then the problem is probably back in the tractor wiring. If it doesn't and the coil is new (assuming it works), then it could be the ignition module. I can tell you how to check that or you can look in the Onan manual. Let me know what you find.

[Dennis 0]

Dennis, have you checked to see if there is voltage on the positive side (small post) of the coil with the key on when the tractor dies and won't start. If there isn't, I would try to jumper a wire from the positive side of the battery to that same post. (Only do this temporarily to see if it starts because you will have no fuse in the circuit). If it starts, then the problem is probably back in the tractor wiring. If it doesn't and the coil is new (assuming it works), then it could be the ignition module. I can tell you how to check that or you can look in the Onan manual. Let me know what you find.

Jumping from the positive post on the battery to the positive post on the coil had no affect at all, still no fire.

The ignition module? How do I check that? Thanks DR

[Dennis 0]

I found this PDF online for checking the coil and ignition module.

http://www.woodmizer.com/us/customerservic...85f0c63b17d.pdf

I will give this a shot

[norman 0]

I found this PDF online for checking the coil and ignition module.

http://www.woodmizer.com/us/customerservic...85f0c63b17d.pdf

I will give this a shot

http://groups.yahoo.com/group/Onan_Engine_Club/

[300zx 7]

Dennis, the test you found will work to check the ignition module. Have you run it yet and what were the results? For your information, the Onan manual says to measure the voltage at the negative side of the coil (large terminal) while hand rotating the flywheel (easiest done with the plugs out). The voltage should change from about battery voltage to about 1.5 volts back to battery voltage each revolution. If you want to check your new coil, it should have 2.9 to 3.6 ohms across the terminals and 14,500 ohms to 19,800 ohms across the plug wire sockets.