Cummins Onan 5500 LP

[rwilkins]

A Cummins Onan 5500 LP was installed aftermarket in March 2021 on a 310GK. The generator has 15.6 hours on it and it will not start.

I've checked the following:
1) Oil level (good) [emoji736]
2) Battery (good) [emoji736]
3) Recently fired up as of 2 weeks ago[emoji736]
4) Propane tanks were recently re-filled with gas, have unhooked and hooked them back up.[emoji736]
**Note, the other appliances (i.e., refrigerator, furnace, etc.).

The generator was installed in March by a local specialist professional who only does RV generator work, and it worked fine. I've combed through the Cummins Manual (https://www.granddesignrv.com/sites/...r%20Manual.pdf).

Is there a trick I am unaware of? Thoughts?

Thanks in advance!

[KatrinaAnon]

First what code is it throwing when it fails top start?

Another question if the LPG tanks are full, is it cold outside? Full tanks may not, in cold weather, generate enough gas for the generator to operate. Install a half full tank, which will have more vapor space, and try again.

Always record the codes as it will provide clues to the failure.

[rwilkins]

Thanks for the remarks/thoughts.

The issue (I failed to mention) is there is no code (alpha, numeric, or otherwise) on the display inside the coach; the generator will crank and tries to start, yet will not turn over. We’ve tried priming several times, even up to 25-30 seconds.

The unit was installed on the coach March 2021, and have put ≈14 hours of use since then. The average temperature has been 89° in the last few weeks, and the only change has been we’ve replenished has been since propane tanks have been filled.


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[Redapple63]

Some basic questions...

1. is it getting fuel?
2. There is an oil level sensor that could be preventing it from starting, check the sensor.
3. Is it getting spark?

I have lots of experience with the gas version of the 5500, not so much with the propane, not sure how much translates though

[rwilkins]

Some basic questions...

1. is it getting fuel?
2. There is an oil level sensor that could be preventing it from starting, check the sensor.
3. Is it getting spark?

I have lots of experience with the gas version of the 5500, not so much with the propane, not sure how much translates though

1) unknown, need to conduct a test since that seems to be the culprit
2) any suggestions on the oil sensor? It def has enough oil
3) yes, it’s getting a spark


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[offtohavasu]

Does it have TOO much oil?

[rwilkins]

Update (07/09/21):
We took the generator into an authorized Cummins local service shop and the issue was a faulty/blown Solenoid fuse.

Replaced for no cost (under warranty) and it fired right up! It was a coincidence that the fuel source (propane) was replaced around the same time that the generator wouldn’t turn over.


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[supertinner]

My onan did the same thing. The hose from the regulator to the carb was deteriorating and cracking. I replaced the hose and it started right up.it wasntgetting enough suction to open the regulator.it only takes a small hole

[Redapple63]

Glad you got it figured out and it turned out to be a simple fix.