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Gas Onan and Heat

Yahoo Message Number: 9655
Had opportunity for first-use of our gen-set during a 4-week trip North (from Florida)...three Wal-Mart stays, and four days at PA campground without shore-power, after a storm. First W-M nite, in central VA, had Onan 5500 gas gen-set shutting down several times. At first I thought it might be condensation in the gas tank, but figured pick-up was higher than one for the chassis, so then deduced overheating, and opened the door on the gen-set compartment...still quit several times (ambient temp in the 90's). This happened each time at W-M's (all 80's and 90's), but it worked fine (as-needed) during lost-power incident at campground (temp in low 70's).

Wondered if there were any other similar experiences out there. I'm guessing it's vapor-lock; 3psi on the Onan fuel-pump (at the gen-set) could easily be overcome by "boiling" fuel. Thinking I might try installing another electric pump (adjustable) close to the tank, and replacing plain rubber fuel-line with insulated line, between pump and carb, and investigating means of cooling carb too.

Gen-set has about 500 hours on it, and will be replacing the fresh 30-hour mineral-oil (seller changed it before we bought) with good synthetic - have been using Mobile-1 20W50 in my current air-cooled bike, and it does better with pressure, cleanliness, and lubricity well past what mineral oil did on previous bikes. Figure that hot air-cooled gen-set engine will benefit too.

Re: Gas Onan and Heat

Reply #1 –
Yahoo Message Number: 9656
Attachments :

    Did you read the error code? Do you have an owners manual for the genset? You should get a fault code if the genny shuts down without use of the stop switch. The fault code will help source the problem.
    "Following a fault shutdown, the indicator light will repeatedly blink 3 or 4 blinks at a time. 3 blinks indicates a servive fault code. Press Stop once to cause the 2 digit, 2nd level fault code to blink. (Pressing stop a second time will stop the blinking)." Pressing stop 3 times within 5 seconds will display the last fault code on memory.
    Shutdown faults can range from not reaching temp fast enough, overheating, overvoltage, undervoltage, control card failure, etc.
    For example per manual (these are from a 4k gas manual but s/b similar)
    "2nd level fault code 36 is "genset stopped without fault condition"
    Check air filter
    Check for blocked or damaged exhaust system
    Vapor lock
    Check Carb altitude setting
    Verify chock operation
    Measure fuel pump pressue
    Plus a few 'electrical' possibilities

    This sounds a bit complicated, but it's really a fairly simple process to get the error codes after you've done it once
    If you don't have a manual, and get the error code, just post it and I can give you the code from my 4k manual as it s/b the same or someone with a 5500 manual can help. There is a shop manual for the 5500 diesel in the files section. Some of the codes might be the same, but I haven't verified this. I have a 5500 diesel in our GS
    Greg
    MN

    From: KodiakChassisClassC@yahoogroups.com [mailto:KodiakChassisClassC@yahoogroups.com] On Behalf Of JT
    Sent: Thursday, August 16, 2012 8:57 AM
    To: KodiakChassisClassC@yahoogroups.com
    Subject: [KodiakChassisClassC] Gas Onan and Heat



    Had opportunity for first-use of our gen-set during a 4-week trip North (from Florida)...three Wal-Mart stays, and four days at PA campground without shore-power, after a storm. First W-M nite, in central VA, had Onan 5500 gas gen-set shutting down several times. At first I thought it might be condensation in the gas tank, but figured pick-up was higher than one for the chassis, so then deduced overheating, and opened the door on the gen-set compartment...still quit several times (ambient temp in the 90's). This happened each time at W-M's (all 80's and 90's), but it worked fine (as-needed) during lost-power incident at campground (temp in low 70's).

    Wondered if there were any other similar experiences out there. I'm guessing it's vapor-lock; 3psi on the Onan fuel-pump (at the gen-set) could easily be overcome by "boiling" fuel. Thinking I might try installing another electric pump (adjustable) close to the tank, and replacing plain rubber fuel-line with insulated line, between pump and carb, and investigating means of cooling carb too.

    Gen-set has about 500 hours on it, and will be replacing the fresh 30-hour mineral-oil (seller changed it before we bought) with good synthetic - have been using Mobile-1 20W50 in my current air-cooled bike, and it does better with pressure, cleanliness, and lubricity well past what mineral oil did on previous bikes. Figure that hot air-cooled gen-set engine will benefit too.

    Re: Gas Onan and Heat

    Reply #2 –
    Yahoo Message Number: 9657
    I have a copy of the service manual for Onan 5500 Gas. It is too big to load on this site. If you would like a copy give me a email address that will allow a 9 mb file to be sent.
    Best
    Ron Hall

    Re: Gas Onan and Heat

    Reply #3 –
    Yahoo Message Number: 9658
    Guys,
    Try using a web location called "Dropbox". Sign up is easy and you invite people to view the folder you place on dropbox. It's free. They start you off with a sizable chunk of storage space. Great for sharing large flies/folders. I send large folders to my band mates all the time. Hope this helps! https://www.dropbox.com/

    Bobby

    Re: Gas Onan and Heat

    Reply #4 –
    Yahoo Message Number: 9659
    Thanks, guys - downloaded user and install .pdf's from Onan. No, I didn't check trouble codes (didn't know there was such a thing) - didn't have the manual...but I do now. Noted operating range up to 120 degrees F - as-tested. Am inclined to think I was pretty close when I guessed at vapor-lock - ambient in the parking lots we stopped in was over 90, and combined with higher generator compartment temperatures, alcohol-infused gasoline, and (relatively) low-pressured fuel pump, it's a pretty good formula for it. Then, when it ran fine in the 70-degree range...

    Air filter was clean before we left. First thing I thought of when it happened was oil level - but was good. Alt setting was ball-park (rich, if anything).

    Coach is in the shop now, for awning replacement and repair to slide-out roof, after being attacked 80-90 mph straight-line winds. Will check gen-set on a high-ambient run-up when we get it back - after new filter and synthetic oil-change. This time I'll have the troubleshooting codes handy. Will let y'all know. Thanks again.

    Re: Gas Onan and Heat

    Reply #5 –
    Yahoo Message Number: 9660
    Just a through from a novice GS / Kodiak practitioner,  GenSet will shut down when fuel tank is less than a about quarter tank to keep from running RV out of gas.  Had me baffled till I figured it out. Just something to consider if you have not already.

    John Kirkgasser
    Reverse the e-mail spiral: http://emailcharter.org/