Onan 5500 5.5HGJAB 1038D SPEC D

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phil-t

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Ogdensburg, NY
I have this gas generator in my 2010 WBGO, low hours. Has been running flawlessly. I was using it two nights ago; ran for several hours and quit. No codes thrown!  Tried to restart it several times; it will start and run for 2-3 seconds and quit.  Thought maybe low fuel (just over 1/2 tank in MH).  Filled up the next day and gave it a try.  Same thing, start, run for a 2 or 3 seconds and quit.
I have not done a lot - looked for loose wires, connections, etc.
Any ideas from some good folks here are welcome.
 
The HGJAB generator uses a microprocessor based control module.  It's sensitive to interference and something like a bad spark plug or arcing from wet or defective spark plug wiring can make it do strange things.

It will also "go to sleep" and shut down the engine without throwing a code if the voltage reaching it drops below 9 volts.

Start by checking the connections to the battery for loose or dirty connections.  The generator doesn't produce it's own 12 volts, it relies on the external voltage from the battery.  Usually generators are connected to the house batteries, which are charged by the RV's converter when the generator is running.

If all of the battery connections are good, find the multipin plug connecting the generator to the outside world and look at it's condition.  Sometimes unplugging and replugging it will clean a dirty connection and restore the operation.  If this works, get some electronic contact cleaner and use it to clean the contacts.

All of the above comes from the generator's Service Manual.  If cleaning the external battery and control connections doesn't solve the problem you (or your service person) will have to delve deeper into the generator.  Here's a link to the Service Manual in case you need it:

Onan HGJAA to HGJAF Service Manual
 
I had the same generator in my Vista. Ours did the same thing on a trip out west. It did it a couple times and then came out of it. Then finally quit. No codes. I crawled under the unit and checked the fuel pump. It had quit. I went to local parts store and bought a generic 12v fuel pump and put it on. Also installed another in line filter before pump just to be safe. Took care of the problem. You should be able to hold your swicth on the generator to prime. Should be able to hear it running. If not it's the fuel pump
 
Ghostman said:
You should be able to hold your swicth on the generator to prime. Should be able to hear it running. If not it's the fuel pump

Yes, can hear the pump run when prime is pushed.

++++++++++++++++++++++++++++++++++++++++
Thanks Lou, for the link to the service manual, I will make your suggested tests.  We are traveling now and maybe tonight, when we stop.

Traveling west on I-40 from Memphis - warm/hot weather makes boondocking difficult without the genny.
 
I have the same basic model (not sure about the 1038D SPEC D). It had 300 and some hours on it.

Got to where it would run 15 to 45 minutes then quit.

A new fuel pump solved the problem.

Tom
 
Thanks guys.  Did the simple tests for DC and control wire connections - all good.  I'm ordering a new fuel pump and filter, whenever we get a chance (hopefully can pick them up at a local autoparts store).  Till then we deal with it by staying in parks with powerhookups.  8)
 
phil-t said:
Thanks guys.  Did the simple tests for DC and control wire connections - all good.  I'm ordering a new fuel pump and filter, whenever we get a chance (hopefully can pick them up at a local autoparts store).  Till then we deal with it by staying in parks with powerhookups.  8)

I just bought one at parts store. They carry two different PSI pumps. I bought both but put the lowest on. It worked fine. I had a spare then. Also crimped on spade connectors to make it easy to change if I need to again.
 
Ghostman said:
I just bought one at parts store. They carry two different PSI pumps. I bought both but put the lowest on. It worked fine. I had a spare then. Also crimped on spade connectors to make it easy to change if I need to again.
So, which parts store and pump (part #) did you get?  I'm having a hard time finding a local parts store that has it, while I am traveling, I'm looking!
I came up with the Airtex E11015 as a replacement, on Amazon.  I will have to wait till we hit a park for more than a day or two to order it though.
Other alternatives than the $$$$ Onan part?
 
Just buy a generic 12volt fuel pump. About $20 . I think psi was around 3psi if I am not mistaken.

https://www.amazon.com/dp/B071JFDKB2/ref=sspa_mw_detail_1?psc=1
 
Well, found the specs on pressure, etc.  Had a NAPA near me so I removed the old pump and filter, filter good, pump seemed OK but maybe weak on pressure.  Took it in No Go!  Same issue - starts and then shuts right down. 
I will be driving by a Cummins Service Center tomorrow in Amarillo, TX.  Gioing to call them in the AM and see if they can look at it.  Oh well, I tried.  Like was said, there is an electronic control board that is beyond my capabilities to trubleshoot.  Did all the minor stuff indicated in the service manual.

Thanks for the help guys.
 
Ended up at the Cummins Service/Repair Center in Albuquerque, NM yesterday at 7AM, one busy place.  (I had called them the day before for an appointment) Six hours later we were back on the road.  NOT fixed.
They came out, diagnosed it as a speed sensor issue.  In the tech's words, Not good. Meat that the control board was not receiving anything from the generator end - could be a belt, or the generator.  It is the generator.  Needs a new one.  No parts available anywhere in the US.  They buttoned it back up and we were on our way.  They are going to keep track of the backorder and call when they can get the parts.  We'll see where we are in out travels; may be going back to them.
Can't say enough good about this place.  Very customer oriented and accomodating. Comfortable lounge with internet, coffee, TV, etc. to wait in.  They even have 50A hookups for extended stays.
They probably had about 2 hours in the diagnosis and troubleshooting, with the partial teardown, etc. Gave me a parts list and copy of their work order and never charged us a penny!  That's right $0.00 and we were on our way.  So, in hot weather, and/or every 2-3, days we need a hook-up and plug in to get things back in order; that's all.  Not going to ruin our trip at all.
 
phil-t said:
Ended up at the Cummins Service/Repair Center in Albuquerque, NM yesterday at 7AM, one busy place.  (I had called them the day before for an appointment) Six hours later we were back on the road.  NOT fixed.
They came out, diagnosed it as a speed sensor issue.  In the tech's words, Not good. Meat that the control board was not receiving anything from the generator end - could be a belt, or the generator.  It is the generator.  Needs a new one.  No parts available anywhere in the US.  They buttoned it back up and we were on our way.  They are going to keep track of the backorder and call when they can get the parts.  We'll see where we are in out travels; may be going back to them.
Can't say enough good about this place.  Very customer oriented and accomodating. Comfortable lounge with internet, coffee, TV, etc. to wait in.  They even have 50A hookups for extended stays.
They probably had about 2 hours in the diagnosis and troubleshooting, with the partial teardown, etc. Gave me a parts list and copy of their work order and never charged us a penny!  That's right $0.00 and we were on our way.  So, in hot weather, and/or every 2-3, days we need a hook-up and plug in to get things back in order; that's all.  Not going to ruin our trip at all.



Do you have a part number? Ebay has plenty of Onan parts.
 
I do, and I'm searching.  So far, all blanks.  It would be a bit of work for the repair - unit removal from the MH and replacing the generator.
I have a service plan and they have authorized the repairs.
 
Heli_av8tor said:
I have the same basic model (not sure about the 1038D SPEC D). It had 300 and some hours on it.

Got to where it would run 15 to 45 minutes then quit.

A new fuel pump solved the problem.

Tom

Tom,  we probably have the same unit.  How many hours on your generator?  Also, how difficult is the install?  Ours has been running fine but we had to replace the fuel pump on our old Aerbus which had about a 1000 hours at the time.  The replacement was done by a service facility.  I'd prefer to carry a spare and be able to install if not too difficult. 
 
garyb1st said:
Tom,  we probably have the same unit.  How many hours on your generator?  Also, how difficult is the install?  Ours has been running fine but we had to replace the fuel pump on our old Aerbus which had about a 1000 hours at the time.  The replacement was done by a service facility.  I'd prefer to carry a spare and be able to install if not too difficult.

Gary,
That's an easy DIY.  Disconnect the fuel line from the carb fitting (easy), Go underneath, disconnect the line comming from the tank at the fuel filter/pump assy, Remove two 10MM bolts (1/4 or 3/8  drive ratchet-socket-and 6" extension) and pull down.  That's it.  If you are going to carry a spare, include 2 1/2' of 1/4" fuel line, clamps, and a filter.

Wish that had been my problem  :-[
 
Here's a PIC of my pump (installed), looking up from underneath.  Left side is the 90 deg. headed up through the base to the carb.

Also, need to unplug wires to the pump.  Just follow the cable up through the base to where they are plugged together.

 

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