This topic contains 6 replies, has 4 voices, and was last updated by 
Marsha & Dewey 6 months, 3 weeks ago.
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We had a problem with our Onan 4KY generator starting this past weekend. Upon examination we found the chassis ground wire had fallen off due to screw rust out. We reconnected it with a pair of Visegrips but still no luck starting. Thinking that there may not be enough power in the house battery to drive the starter, we started the V10 and when we pressed the start button on the genset we could hear the alternator bog down. Wondering if trying to start without the ground engaged the starter which now is stuck? or worse, have we burned out the starter? Does anyone have experience with this?
Found an interesting reply in this thread, may be of help – http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/23497447/print/true.cfm
About mid way down
Posted By: Chinook on 12/19/09 06:34pm
This appears to be sign of a low battery or bad cable connections with the resulting “stuck starter”. I had a similar problem with my generator. I checked it before a trip to Alaska and all appeared to be fine. Used it a couple of times on the trip and then it wouldn’t start. It got to the point that it wouldn’t turn over and just made a click (klunk) that sounded as if the starter was jammed.
After returning home, I found information this forum that explained that sometimes the piston in the engine could stop near the top of the compression stroke and the starter motor then could not turn the engine over. The solution was to turn the engine over by hand so it was past the top of the compression stroke.
I found that by putting a wrench on the nut on the flywheel, I could get the engine rotated past the compression stroke. I also discovered that I was getting a big drop in the 12 volts as I tried to start the generator. As a test, I used jumper cables from my truck directly to the generator (negative to generator frame – positive to battery side of starter solenoid) and it started instantly. In my RV, the frame was used for the negative wire and the connections from the frame to the generator had corroded and although I could get a 12-volt measurement, the corroded connections would not allow enough current to pass to run the starter. In addition to replacing the corroded connectors, I ran a heavy gauge copper wire from the battery ground to the starter ground. This solved my problems. As stated above, a large drop in voltage when trying to run the starter indicates a bad connection.
You might need to check ALL of your ground connections from the generator all the way back to the batteries. A bad electrical connection increases the resistance in a circuit. Ohm’s Law states E=IR where E = voltage I = current and r = resistance – Since the battery voltage will not increase (it actually decreases with each attempted start), increased resistance causes a decrease in current. With a decrease in current, the starter motor produces less torque (turning effect) because the magnetic field produced in the starter is proportional to the current. When the piston in the motor’s cylinder goes upward during the compression stroke the volume of the area from the top of the piston to the bottom of the cylinder head becomes less, According to Boyle’s law, if you reduce the volume of a quantity of gas, the pressure will increase. When the force of the gas pushing down on the piston (pressure) equals the torque of the starter the starter motor stops turning. Attempted restarting does nothing to change these forces and the starter motor in an attempt to turn just runs the starter bendix into the flywheel producing the clicking sound. By physically turning the motor past top dead center, by pulling on flywheel or placing a wrench on the flywheel nut, the piston starts on its downward stroke and the pressure becomes less so that the torque of the starter is adequate to rotate the motor.
LoveYourRV.comGosh, Ray, that is excellent! Certainly worth a try! Let us know how it goes, you guys…
1996 Honorbuilt Eldorado C320 "Lurch" | Chewbacca is my co-pilot
Ray,
Thanks so much for the info link. This afternoon I reconnected the ground wire that fell off, reached in and turned the flywheel by hand and heard the starter disengage from the ring gear! Then I primed and pressed the start button and VOILA! running genset!!!! I believe we have had a poor ground for some time now, because now that the ground has been cleaned and reconnected the starter sounds like it’s brand new! We are soooooooo happy!!!
Awesome, great news!
LoveYourRV.comWow, spectacular!! Way ta go, Ray!! And congratulations Bob and Nancy! I bet Miss Lilly Greyhawk feels so much better!
1996 Honorbuilt Eldorado C320 "Lurch" | Chewbacca is my co-pilot
This is just the type of help that makes this site so wonderful! Thanks Ray!
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