Onan 5500 HGJAB Hard Start fault code 37

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garyb1st

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Genie starts, runs erratically for a few seconds, then quits.  After 4 or 5 tries it starts then slowly and gradually gets up to speed.  We get a fault code #37 when it fails to start.  No where near a Cummins or independent facility which is what manual recommends. 

Generator has been serviced regularly since we've owned the motorhome and has been run periodically when sitting.  We've been on the road for almost 3 weeks and it started and ran fine on two different occasions when boon docking.  The last time at 7,500 feet, it shut down after starting.  As mentioned it took 4 or 5 attempts to get it to continue running.  Then it would run for several hours until we shut it down.  Powered the water heater and a space heater with no problem.  So about a 50% load.

The only possible service that may have been missed is cleaning the spark arrester.  When it tries to start it sounds like it's starved for gas.  Tank was full and as mentioned it ran after 4 or 5 attempts. 

 
I looked online Gary and most people seem to think that fault code 37 is caused by varnished fuel and clogged carburetor jets - the genny sitting too long without running. The fix seems to be letting it run for an extended period of time (assuming you can get it running) or taking the carb off and cleaning it.

Kev
 
Code 37 indicates a failure in the ignition circuit which could be a host of issues. I found this link that should give you some help.

http://www.irv2.com/forums/f121/onan-generator-problem-code-37-a-218449.html
 
Kev, varnish is possible but would it run for 15 hours before having problems.  I was hoping something simple like cleaning the spark arrestor but most of what I've read states it doesn't do much.  I'll start it up, hopefully, when we leave tomorrow and let it run while on the road.  We'll turn on both AC's and the water heater which will require about 30 amps.  At our altitude, that should give it a good work out. 

Henry, I came across the same link.  The fault code 37 has many possible causes.  While it doesn't indicate a fuel issue, based on how it starts, that's still the only thing that makes sense to me. 

Right now, the biggest problem I'm having is finding a service center closer than 200 miles. 
 
It does feel like a fuel issue. For a few bucks put a new properly gapped spark plug in it. If that doesn't help, I would pull the carb and manually clean it. You can run carb cleaner in the fuel but it is not as effective as a manual cleaning.
 
Do you have a choke lever on your 5500? The Onan 7000 in our previous coach had one, and it would definitely make a difference on how well it ran. I think it would have even more of an effect at higher elevations.

Having this problem after running well for 15 hours does make me wonder if varnish is causing the problem, but it never surprises me how fast the crappy fuel we have around here can go bad. I've also learned from experience that a gummed up carburetor can fake out some Onan diagnostic codes that point to ignition problems.

I think you were with us at KOFA when we were troubleshooting Ed's generator problem. It would start, run roughly for a short time, then shut down. It kept throwing a fault code (16 IIRC) indicating that the spark plug was bad. However, when we inspected the plug, it was fine. It turned out that he hadn't run the genny in nearly a year, so it was all gummed up. It finally stayed running after we sprayed starter fluid into every orifice and hose we could reach, and let it sat for a bit.

Kev
 
Kev, I think you're right.  I started the Geny from the outside and after two attempts pushed a spring loaded doohickey, which is likely the choke and it got the Geny up to speed.  It's been running perfectly since, maybe for an hour.  I've done a fair amount of research and am pretty sure it's a fuel issue.  Can't see any need to have an Onan dealer do a quick inspection for $100. plus an hour labor (because they're slammed) and can't do anything other than a quick diagnosis.  So with luck and maybe a can of carb cleaner I'll save a few bucks.

Thanks for the help.
 
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