Hello all ,I'm the new guy on the block. I recently purchase a 2002 Winnebago Journey with 5.9 Cummins engine. Only 25,00 miles on it and got a great deal on it.Having said all that, It has a Onan HDKAJ 7500 quiet diesel generator that will not start. I have the service manual and have gone through what I think is all of the simple checks and still no start. Have changed fuel filter, primed pump, checked fuses, fuel flow test, fuel coolant and oil levels are correct.Here is my question,The person who owned this says generator was running a very short time prior to my purchase. I can't say as whether to believe him or not. I do however think he may have ran it out of fuel as it has a code 36 in the fault system. Fuel tank was low when purchased but full now. I have tried everything I can think of to clear this fault code but it is still there. Disconnected batteries, pressed stop button after retrieving code primed pump, etc. If this code is still in the circuit board will keep fuel shut off at governor? I am getting no smoke at all, either blue or white, indicating no fuel flow. It cranks freely. I'm stumped....Hopefully someone has had this before and can help.Thanks in advance and I look forward to being a contributing member for this forum.

if you fuel tank is low than it won't supply the genny with fuel. how much fuel is in the tank?

Some generators will not start/run if the main coach fuel tank is less than 1/3 full. This is an arbitrary fuel level as it varies with each RV. Make sure that your fuel tank is full and then check the fuel filters going to the generator.

Sorry forgot that part.Tank was low when purchased but full now.

Fuel code - only way to find the problem is to "find the problem"How far up the line are you getting fuel flow?Blocked or criped fuel line/ filter.Lost prime?Getting air, sucking through a crack or bad gasket.Just keep going along the fuel line till the problem shows itself.BOL,

are you holding the start button long enough?

onan 7500 quiet Diesel | Good Sam Community

26 Replies

gfs1943
Explorer
Apr 04, 2015
rgatijnet1 wrote:

Glad that it is fixed but sorry for the big hit to the wallet. Thanks for the update.

X2. We really appreciate your posting the "fix". I believe that's a pretty rare failure. Hope your wallet recovers in time to get some camping in!
rgatijnet1
Explorer III
Apr 04, 2015
stevebyrum1 wrote:
Well the onan 7500 quiet diesel is finally running. I finally broke down and took it to the Cummins onan shop here in Amarillo. After removal and inspection, we found that the injector pump had catastrophically failed. They said it was the first they had ever seen. $2000 dollars later its up and running.
Should you ever need service I would recommend these guys. As expected, not cheap, but courteous and helpful. Let me in the shop to look things over while it was torn down. Good learning experience and now I know what it looks like behind those panels. Quite simple actually.
Many thanks to all who posted trying to help. .

Glad that it is fixed but sorry for the big hit to the wallet. Thanks for the update.
stevebyrum1
Explorer
Apr 04, 2015
Well the onan 7500 quiet diesel is finally running. I finally broke down and took it to the Cummins onan shop here in Amarillo. After removal and inspection, we found that the injector pump had catastrophically failed. They said it was the first they had ever seen. $2000 dollars later its up and running.
Should you ever need service I would recommend these guys. As expected, not cheap, but courteous and helpful. Let me in the shop to look things over while it was torn down. Good learning experience and now I know what it looks like behind those panels. Quite simple actually.
Many thanks to all who posted trying to help. .
keepingthelight
Explorer
Mar 23, 2015
IF you just recently changed the fuel filter, then you now have air in the system. You will need to crank it over and over again to get the air out. It should start, if not I would google "onan 7500 starting problems" to see if that may help.

good luck;)
Mike_Hohnstein
Explorer
Mar 18, 2015
Might want to chase down a Cummins/Onan facility. We have one in the Milwaukee area, helped me out with a Onan problem.
Canadian_Rainbi
Explorer
Mar 18, 2015
Congratulations on your new to you rig. We have a 2002 Itasca Horizon, a very close cousin. Hope you get the gen sorted. We have never (touch wood) had a problem with ours.
stevebyrum1
Explorer
Mar 17, 2015
I haven't posted in a while but I am reading all the posts. Lots of good advice and it is much appreciated. Still working on it. Will advise if I get a solution.
ssia2485
Explorer
Mar 17, 2015
Code 36 is a low engine speed fault not shut down by the controller. I just had the same fault on mine. Changed the fuel filter and no more problems. Like the others have said hold the button on the stop mode until you hear the fuel pump run and hold for 30 seconds to prime the system. It could also be the air filter is clogged and the engine is not getting enough air to run. I would check that too
bigdisplay
Explorer
Mar 17, 2015
filadelfia wrote:
Have you replaced the fuel filter? It is located behind the panel on the bottom of the unit near the oil filter.

Good luck Don

READ OP POSTS he clearly says
Have changed fuel filter, primed pump, checked fuses, fuel flow test, fuel coolant and oil levels are correct
bounder39zman
Explorer II
Mar 17, 2015
YOU SAID YOU DID A FUEL FLOW TEST. WERE YOU MEASURING AT RETURN LINE?
YOU SHOULD GET A MIN. OF .4 PINT /MINUTE. IF SO, THEN FUEL PUMP, FILTER,
TANK LEVEL ARE NOT PROBLEM.
BTW, FAULT CODE WILL STAY IN MEMORY UNTIL REPLACED BY ANOTHER CODE.
IF YOU ARE GETTING NO SMOKE WHILE CRANKING,( FROM TAIL PIPE), THEN YOU HAVE NO FUEL BEING DELIVERED TO INJECTORS. IF UNIT HAS BEEN SITTING FOR SOME TIME, WITHOUT RUNNING, VERY POSSIBLE FUEL RACK IN INJ. PUMP IS STUCK. DIESEL THESE DAYS HAS SHORT SHELF LIFE. IF SO, PUMP WILL NEED TO BE PULLED AND CLEANED BY QUALIFIED F.I. REPAIR SHOP. OTHERWISE YOU PROBABLY
HAVE PROBLEM WITH ELECTRONIC GOVERNOR. ACTUATOR NOT WORKING. OR GOVERNOR CIRCUITS ON CONTROL BOARD(PART OF INVERTER/CONTROLLER ASSY)