Onan 5500 propane generator

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Semicrazy

Semicrazy

Member
Joined
Mar 18, 2018
Posts
8
Location
Buckeye, Arizona
I have an Onan 5500 propane generator that has run like a champ for the last 10 years. All of a sudden it starts sometimes and sometimes it doesn't I took it to the local Onan service department in Phoenix Arizona they charge me $175 to tell me that it runs like a champ of course it ran like a champ they were looking at it. What it seems to me is it doesn't get any propane I'll try to turn it  one time and it fires right up and runs for hours then I'll try and turn it on the very next day and it will not start almost like it's out of propane but yet the propane is completely full. I was speaking with a gentleman that told me that there's probably an oil build-up in the fuel line where the propane goes in does that sound reasonable? I hate to tear this whole thing down chasing rainbows. Any help would be appreciated thank you. Here are the things that I have done so far. I have replaced the regulator twice I have replaced the hose that goes from the regulator into the propane tank twice. And of course I took it to the  Onan service center in Phoenix Arizona only to be told it runs like a champ.
 
Since you indicate it might not be getting enough propane, perhaps opening the valve slowly on the propane container might help. I'm not sure about your particular tank, but many tank valves shut off if they see too much propane starting out too quickly. Otherwise, perhaps Lou or Gary will see this post.
 
The oil build up theory might actually be the problem, but if so, there's an easy fix. Turn off the propane, disconnect the line at the generator, slowly turn it back on, then off, then reconnect it.

When I installed a catalytic heater, the manual suggested installing a low point drain in the propane line.

Joel
 
Some propane gensets run on liquid propane and have their own port into the LP tank so they  can suck liquid directly.  If this is one of those, there should be no "excess flow" control on that port.  For vapor-feed gensets, it till requires a high flow rate and the line is usually isolated from other appliances so that one does not interfere with the other. How is your genset plumbed into the tank?  And is it a fixed ASME tank or portable LP bottles (DOT spec)?  Is it possible that another high-demand appliance (furnace or water heater) is sucking enough propane to interfere with the genset?

An oil build-up doesn't usually come and go, but it is conceivably a problem. Would not be my first suspect, though, since the genset runs fine much of the time.
 
  On my 25-year-old Onan 6500 LP the small metal tube running alongside the exhaust pipe (that's what heats liquid to vapor) and the regulator were seriously full of oil, so much so that sufficient propane flow was eventually choked off. These aren't regular service items; the generator had to come out to get at them.
 
I have an Onan 5500 propane generator that has run like a champ for the last 10 years. All of a sudden it starts sometimes and sometimes it doesn't I took it to the local Onan service department in Phoenix Arizona they charge me $175 to tell me that it runs like a champ of course it ran like a champ they were looking at it. What it seems to me is it doesn't get any propane I'll try to turn it
Click to expand...

Had a similar situation that began with the genset starting sometimes, but not other times. Found that a short squirt of WD-40 into the inlet and it would start and run. Finally determined the problem was a leaking flex hose from the regulator to mixing valve leaking. During start it would suck outside air into the line, preventing start. Once the genset started, it would run fine. Replaced hose. - $6.77
 
thank you red T for the suggestion as I indicated earlier in my statement I have replaced the hose twice and the regulator twice so I don't believe there's a crack in the hose but I will try the WD-40 method I appreciate it
 
Gary RV Wiz. The generator is hooked to nothing else it has its own stand-alone propane tank. Also the generator runs less than it does run more it hardly ever starts and runs in comparison to not running.
 
well so much for the WD-40 Theory. Still not running. Now it's time now it's time to move on to the next one still trying to disconnect the lines of course they're in the worst place possible what a pain in the ass oh well on word I shall go.
 
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