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Onan 5500 Generator Won't Start


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Hi,

I have an Onan 5500 Gold Generator and it won't start for me. When I attempt to start it, either inside the rig or from the generator itself, I get a clank sound. It's like the generator initially gets power, but then won't turn over. You might also describe it as if the flywheel doesn't spin; it's like it's locked. I checked the oil level, gas, spark plug and the fuel pump seems fine as well. I can hear it working when I prime the generator. 

Any ideas? I am having a hard time even getting a onsite mechanic right now due to them being overwhelmed! I have a great mechanic at home, but I'm not home!!!

Also, at about the same time, all of the lights on the back of the coach went out. I don't have tail lights, turn signals, emergency flashers, brake lights, and the lights won't work on my Toad when it is attached. Would this be a related issue due to a bad ground, etc. 

I've had great luck out of this coach for the last 6 years. I'm not a great mechanic. If anybody has advice for either or both problems, it would be appreciated. I'm trying not to get ran over before I get if fixed!!!!

My coach is a 2003 Winnebago Adventurer 38G. It's on the Workhorse Chassis. It's a gas coach.

I'm new because I've never really had an issue in the last 6 years, be Gentle (LOL)!

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Have you tried holding the emergency start switch and then try to start it? If not, start the chassis engine first, just to be sure you have peak power, then hold the emergency start switch like you would if starting the chassis engine from the coach battery, but attempt to start the generator. It may be that your battery is either discharged or failing and you just don't get enough power to turn it over. If you have a volt/ohm meter, check the voltage across the coach battery and see what it reads when resting.

The lights on the back of the coach may be a fuse problem. I'm very limited in my experience with Workhorse chassis but the Ford F53 chassis has an extra fuse block for the motorhome and several of them are labeled "body builder" followed by running lights, etc. If you have not done so, check for such fuses. Do the other lights work properly on the outside of the coach?

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1 hour ago, Will B. said:

Not my post, but @Kirk W, thanks for all you do to help folks like us that have questions!  I see your responses in here all the time.  Thanks from a stranger!

I just wanted to take a moment to echo your commendation of Kirk.   He helped my wife and I immensely over 8 years ago when we made a 'cold turkey' decision to become Fulltimers... His advice (and others) made a tremendous difference for our success.   We're still here, and quite happy with the Fulltime years.   Kirk was extremely helpful, patient, and encouraging.   And as you pointed out, Will, Kirk's help for others is 'all the time'.   Thank You, Will B, for letting me comment on your dime, and on your excellent comment. 

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Bibs, do you know if the Onan gets its power from the engine starting battery orrrrrrrrr the house RV batteries ????????? Likely the house RV is my best guess not being there.

 Regardless, Ive seen what you describe caused by Low voltage,,,,,,,,,,Weak batteries,,,,,,,,,or SO OFTEN  a loose/burned/resistive ground or other cable or battery connection MORE COMMON then a genset problem. Ive also seen genset starter SOLENOIDS  go bad dropping excess voltage so she cant crank over, even if all else is fine !!!!!!!!!!!! 

 QUESTIONS WHICH ANSWERS MAY HELP:

1) Does it make a difference if plugged to shore power which should (iffffffffff alls well) be charging the house batteries thereby lessening their low voltage as the problem....... 

2) Can you check the house battery voltage when setting (should be near 12.6 volts if charged),,,,,,,,,,,

3) Can you check the house battery voltage when plugged to shore power ??  (should be 13 to 14 or so volts if alls well),,,,,,,,,

4) Does it matter if the engine is running or not ???

5) Does it matter if you have some sort of an "Emergency Start"  push or rocker switch that jumps the engine and house batteries together ?????

 If you had a voltmeter right on the gensets starter terminal or the solenoids OUTPUT (that leads to starter motor) when trying to start THAT WOULD TELL A LOT........If it stays on or near say 11 to 12 volts when cranking that reduces the chances of a bad battery or a bad connection or solenoid as the problem......... 

 HOWEVER if the gensets starter motor voltage (same as solenoids output) drops drastically when trying to crank, that makes me wonder about a bad battery or battery cable/connection or bad ground,,,,,,,,,,,,,,Or some other bad/loose/burned/resistive connection,,,,,,,,,Or possibly a bad solenoid (Ive see their contacts get burned),,,,,,,,,,, If that's the case there isn't enough voltage left to crank her over,,,she cant crank well at low voltage NOR CAN SHE CRANK WELL IF THE STARTER MOTOR ITSELF OR THE GENERATOR IS BAD ...   

 The other light problems makes me wonder about a BAD GROUND CONNECTION ????

 Start with checking grounds and cable connections (Sooooooo often a bad ground or cable connection is the problem) ,,,,,,,,,,Voltage on starter or its solenoid output BOTH when setting (when not cranking there's ONLY voltage on the solenoids input side, when cranking on both if alls well)  and MOST RELEVANT when trying to start,,,,,,,,,,,,,,House battery voltage when setting,,,,,,,,,,,House battery voltage when plugged to shore power,,,,,,,,, Of course the gensets starter motor or its engagement gears sticking/jamming could be the problem if its not a battery or cable or ground problem ....Also a bad starter solenoid (its contacts get burned and resistive) can be the problem even if all else is fine !!!!!!!!!

 NOTE Ive seen starter motors hang/jam causing them to lock up so she cant crank and that can also cause low voltage at the starter when trying crank  IE low starter voltage may the fault of the starter itself or the starter solenoid even if its NOT a battery or cable problem !!!!!!!!!

 Thats enough to keep you busy for now lol Sorry that's the best I have to offer not being there. Cables,,,,,,grounds,,,,,,,,,,,,connections,,,,,,,,,,battereis,,,,,,,,,,,solenoids,,,,,,,,,starter motor or engagement gears,,,,,,,,,,FINALLY HOPE NOT the Generator itself grrrrrrrrrrr

PS If you dont have one, here's a URL Link to a Manual, check it out: Page 22 is Troubleshooting

Cummins Onan QG 5500 Generator Manual (omanuals.com)

 

 Good luck best wishes

John T

Edited by oldjohnt
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First of all, I am forever grateful to you guys for your help. I’m spending most of my days with my family right now, so I haven’t dug into the issue a tremendous amount. I did change the oil, change the spark plugs and I downloaded the wiring diagrams, which I’m trying to make sense of, but I think I’ve figured them out. I checked al the dash fuses as well. This morning I took the wiring diagrams and took about 30 minutes and. Ranked around under the coach. Then I started at the back and unscrewed a ground wire that attaches beside the plug that I hook my toad to with the chord. I thinks it’s called a dog bone, collar or something. I’m learning! It was very corroded, so I took a wire brush and cleaned everything really well and reattached it. I was hoping that was the issue; it wasn’t! So, tomorrow or the next day, I will continue to work myself forward now that I’m a little more familiar with the wiring. If I had to guess, now that so think about it, I would bet so have a bad ground or a bad connection in the area where the house batteries and automotive batteries have all those connections up by the starter area. I remember stopping in Savannah last August, beautiful but blazing hot, and I couldn’t get it to start. I had tested everything and couldn’t figure it out. I finally crawled up under it and tapped on the r starter and pulled on all those cables around the starter and it was gone until I had the same problem about 3 months ago. I did the same thing and I’ve had no problems since. So, maybe I do have some additional bad ground wires or connections somewhere. My generator does start off the house batteries and you can “boost” it with the automotive battery. I have learned a lot, but wiring is still a weakness. I’m most concerned about the lights so I can safely get back to East Tennessee. I have a high school friend there that runs a Moabite repair business in the Gatlinburg area. I’m currently in Northeast Florida. I’m am just super grateful for the knowledge/ education. I’m truly amazed at your all’s kindness. I will carefully go through the rest of your guys advice the next few days and update you to let you know if I get it figured out. 
 

Thanks

Robert

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I'm a NewVer but like with PCs (have you tried rebooting?) I go through some simple checks when I have issues starting my Onan:

Turn off all electrical in your rig especially the big items - AC, Fridge.  I turn off everything.

Check that you have gas.

Are you level?  Slightly out of level on my rig can shut things down.  Low gas and not level is bad.

Edited by RollingOn
cooler phrase found
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Posted (edited)

I appreciate everyone’s help. I had to pull the generator out of the rig and a tech I found is repairing it. He hasn’t gotten back to me, but evidently there’s an issue with the bearings or something is lodged in that area. He said he had even found a walnut stuck in one of them! The starter engages the unit and when it tries to turn it over, something is preventing it from turning. I appreciate everybody’s help. This one was a bit above my pay grade!

Edited by bibs
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2 minutes ago, bibs said:

The starter engages the unit and when it tries to turn it over, something is preventing it from turning. The tech thinks it’s an issue with the bearings.

That is not a problem that I haver heard of before in an Onan. Any idea how many hours of run time it has? I hope that you return to share what is found once you know more.

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I’d be happy to let you know what was wrong. He made that observation from looking at it himself. He’s supposed to be highly trained. He’s the generator guy at the largest RV dealership in the area. I met him on a camping trip and he’s doing it for me as a side job. I’ll be sure to get back with you. He said he’d be done this coming weekend, depending on the availability of any parts he might need. That’s evidently a big problem the dealerships are having right now. 

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bibs, wise choice in taking to a qualified tech, Im sure he will fix the problem. WOW if something mechanical is is locking and preventing the engine from cranking over that's more serious than all the electrical related troubleshooting tips I posted for you above. Let me know what happens

 

Best wishes, take care be safe, Happy Flag  Day

 

 John T     

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Will do John! The gentleman seems to think it’s not a huge issue. There were absolutely no signs something was wrong. It just didn’t crank one day. We will see!

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I have a 7K Onan and what happened with mine is a chunk of carbon broke loose in one of the cylinders and locked up the generator while I was cranking it. I pulled the heads off and cleaned everything up. Luckily nothing broke or bent and it ran fine. 

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It’s a win when it can be fixed without expensive parts. I hope I get that lucky! No word from the tech that has mine. He says he should have it fixed by this Sunday. 

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