| Re: [GMCnet] Onan repair or replace [message #317453 is a reply to message #317448] |
Fri, 12 May 2017 12:38  |
A Hamilto
Messages: 4508
Registered: April 2011
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Johnny Bridges wrote on Fri, 12 May 2017 11:49Jump pin 9 to pin 5 and see if the fuel pump comes on. If so, see if it will crank and run. If it does, the problem is on the control card or its associated connections. Report back. Or download Duane Simmons' troubleshooting file off Bdub's site and it will let you determine the problem.
--johnny
Other things can keep it from running even with a good board. If the board is not getting ~28VAC from the flywheel alternator, it assumes the genset is not running and turns off the ignition and fuel pump. A bad flywheel alternator or a bad voltage regulator can cause that. And corroded connections.
If the oil pressure sender is stuck in the "closed" position, that will tell pin 12 that there is no oil pressure, and the board will turn off power to the coil and fuel pump. That is an easy test - disconnect the terminal from pin 12. Don't run it like that forever, replace the sender and reconnect pin 12.
Either of those should still try to run and then die, because the start sequence bypasses those protections temporarily.
Putting a jumper from 5 to 9 basically takes the board out of the equation. That applies battery voltage to the fuel pump, fuel shut-off solenoid, and coil. If no spark with the jumper, suspect bad condenser(s) or coil or points problem. If it has spark and won't fire, suspect the carb.
Also, the fuel solenoid can get glued shut with gas shellac. Same with the fuel pump, shellac can immobilize the piston.
Everything that can go wrong on the Onan engine can be repaired or replaced, except compression. That is probably the kiss of death, unless someone knows where to buy oversized pistons and rings.
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