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6.5 onan generator-propane

December 14, 2011, 10:27:25 pm

drained oil,installed new filter and 4 quarts of mobil syn.  generator normally starts within 2-3 seconds and has always run great(700 hrs)sinceI've owned coach.When trying to start today it would run a few seconds,then  die. Probably took around 15 tries till it kicked off and ran perfect thereafter.Is this typical?

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Re: 6.5 onan generator-propane

Reply #1 – December 14, 2011, 10:38:52 pm

OK, let's start with the easy stuff first:

Are spark plugs (including that hard to reach back plug) OK and properly gaped?
Have you checked the regulator vent for plug such as mud dobber's nest?

Then the more difficult: #1 cause of hard start in your liquid LP generator if it has not been converted to high pressure vapor (check to see which tap on the propane tank feeds the generator) is long hydrocarbon chain contamination of the propane regulator on the generator.  You can replace the regulator, or get the proper (high temp silicone) gasket set and have it overhauled.

When you open up the regulator, you will probably find more than a tablespoon of a low viscosity grease-like substance clogging the regulator.

There are several other threads on this, including this one: Generator

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Re: 6.5 onan generator-propane

Reply #2 – December 14, 2011, 10:55:03 pm

thanks Brett.. the one thing i knew to check was vent and it was clear.After it did start i ran it for 20 minutes with load(a/c) ...no issues....restarted it couple times and it's running fine...I was just trying to figure out why it struggled to start after simple oil change.

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Re: 6.5 onan generator-propane

Reply #3 – December 15, 2011, 06:44:28 am

Changing engine lube oil & filter has nothing to do with the issue.  Would recommend changing the gas pickup from the liquid side to the vapor side, this way you eliminate the oil mess in the regulator.  Oil in the regulator is a normal issue when using the liquid from bottom of tank. why using fuel from the upper side of tank prevents the oil issue.  Should be a simple plumbing change.
Would replace or clean up the regulator by taking apart and cleaning, replace would be preferred for most.
FWIW

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Re: 6.5 onan generator-propane

Reply #4 – December 15, 2011, 09:00:36 am

I doubt that this procedure is kosher but I have cleaned up a goooey LP regulator by pouring alcohol into it and letting it set then gently blowing out all the openings, may take twice or so to get the black goo cleaned out. This got me by til I could replace it which is the better solution.
Gary B

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Re: 6.5 onan generator-propane

Reply #5 – December 15, 2011, 09:56:21 am

Dale, I had a similar problem with my Emerald III Onan and it turned out to be a clogged air filter. Its very simple to check, just remove the air box and filter and see if it clears up. Good Luck!

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