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aamkajtusu's avatar
aamkajtusu
Explorer
May 15, 2015

Onan Diesel Generator problem

Hello all,
I hope you can help me with my generator problem.

I have a Onan Diesel Generator: 7.5hdkaj11451h. It's in a 2005 Tiffin Phaeton.
It runs like a champ when it runs but shuts down after running for awhile... flashing a 36 code. It was running for 2+ hours when I bought this rig a week ago. Now it's down to about 20- 30 minutes. It sounds like it just runs out of fuel. It is hard to re-start and takes several priming/start operations to get it going. Flashing a 36 error code.

When I purchased this rig the genset would not stay running. The dealer replaced the temperature sensor and ran it for a few hours to make sure there were no issues.

I headed across country and by the time I reached San Diego the generartor would only run for 20 - 30 minutes at a time. I had an Onan dealer service the genset... fuel filter, air filter, oil and oil filter. The genset quit on him too. He by-passed the main fuel tank and said it ran fine. When he put the fuel line back together he put in a second in-line fuel filter and said it was ready to go.

I drove it back to where I was staying and tried to start the generator. It would not run at all and was flashing a 25 or 26 code. I removed in-line fuel filter and re-checked the genset by by-passing main fuel tank.... ran fine... turned it off after 5 minutes. Left second fuel filter off and put a union in. Runs fine for 20-30 minutes, sometimes only 5 minutes and then sounds like it runs out of fuel and shuts down... flashing a 36 code.

Please help!

14 Replies

  • 36 is a phantom error code, 'rpm dropped below 1000 for no reason"

    Most of the causes listed indicate a fuel supply problem.

    run the genny with an external fuel source to rule out any internal problems.

    Check and or replace any annd all fuel filters and rubber fuel lines between the genny and the coaches tank
    It is very possible, even likely, that the problem is cause by an invisibly separated or collapsed rubber fuel line, or a hoole that is allowing the genny to suck air.
  • Big Katuna,
    I don't know about a 2nd filter. The one I removed was the one the guy added when he cut the rubber fuel line to by-pass the fuel tank to see if it would run. For some reason the fuel pump would not pull fuel through the 2nd fuel filter and so the genset would not start. I took it back to him and he said he'd never seen a fuel filter fail right out of the box... whatever. I'm guessing that the fuel pump is going bad but I don't want to jump to conclusions since I have to pull the genset out of the rig to replace the fuel pump since the bolts are sitting on top of the frame and are not easily accessible.
  • Here is some info on troubleshooting

    http://www.justanswer.com/rv-motorhome/48fyr-onan-diesel-generator-model-7-5-hdkaj11451h-2005.html
  • I believe your coach has a second, Tiffin installed fuel filter in addition to the Onan on board filter. Is that the one you eliminated?