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chrisdug's avatar
chrisdug
Explorer
Aug 12, 2016

Onan Fuel pump

I think I know the answer already, but wanted to post in case I missed something related to Onan service secrets...
I have had a problem with the gen shutting down after short runs - load or no load. Mostly about 10-20 minutes. Getting a code of 36. Today, I was preparing to replace the fuel filter, and pulled the line to check flow before the swap. Fuel pump is not pumping at all now. Push the start button to prime, hear the click from a relay, but no pump noise at all and no fuel either.

I assume the fuel pump is dead, but thought it best to post up and see if there could be other causes. Battery is good, and has enough to turn over the gen so plenty to run the fuel pump. Are there other reasons or conditions where the pump will not run at all after the solenoid is engaged?

Thanks in advance for any assistance - this is my first coach with a genset and learning as I go...

For the record - I have an Onan 4000 #KYFA26100K, shows 1031 hours on the meter.

10 Replies

  • WyoTraveler's avatar
    WyoTraveler
    Explorer
    Aug 13, 2016
    When the Onan repairman replaced my fuel pump under warranty I asked him why Onan would still place the pump on the generator when they realized a heat problem was killing them. He said Onan sells complete generator units. The unit mounted in MHs is just an off the shelf unit. If my fuel pump goes out again I'm going to move the fuel pump to the MH frame where it will stay cooler.
  • j-d's avatar
    j-d
    Explorer II
    Aug 13, 2016
    CloudDriver wrote:
    I can post a step by step if you need it.


    Any time ^^^this man^^^ offers to post a step x step, take him up on it! Even if you don't need to do the job he documented. Artistry at work.

    As I recall you need a TORX bit to remove some of the parts, and my recall (getting worse by the day...) says it's a T30. Problem isn't changing the pump, it's getting to it.
  • mgirardo's avatar
    mgirardo
    Explorer
    Aug 13, 2016
    When the fuel pump went in our 4000 KY, it just quit. We were driving down the road with the generator running. Wife was trying to heat something in the microwave and it cut off about 30 seconds after she started the microwave. Couldn't restart the generator. If I recall correctly, we had an error code of 34, which I'm pretty sure meant take it to a shop. It was under warranty and the dealer replaced it. No problems since then. That was 7 years ago, about a month after we bought it.

    -Michael
  • wa8yxm's avatar
    wa8yxm
    Explorer III
    Aug 13, 2016
    Pump may be dead. but also check the wires and connections.. This $0.00 dollar fix should always be step one.. The next step has bigger numbers after the dollar sign.
  • Gjac's avatar
    Gjac
    Explorer III
    Aug 12, 2016
    As bud implied in his post if you have a bad connection you may not be getting a consistent 12v to the pump. This happened to me on a trip. I bought a new one at Napa when I went to install it I found that the butt splice from the 12v supply line to the pump was loose. I put in a new splice and now have a spare pump.
  • chrisdug's avatar
    chrisdug
    Explorer
    Aug 12, 2016
    I saw a couple of videos and it looks pretty simple. Part is ordered and I will get it installed probably next weekend. Thanks for the quick feedback. I was ready to tear into the carb before it completely quit...

    Thanks!
    Doug
  • CloudDriver's avatar
    CloudDriver
    Explorer
    Aug 12, 2016
    I had the same problem with the generator running for 10 minutes or so then surging like a lawn mower running out of gas and then dying. Wouldn't start again unless I let it sit for about 1/2 hour. I tried the prime right after it quit and no sound from the pump, so I figured the pump was heating up and seizing. Replaced the pump and all was well. Pump replacement is pretty easy. I can post a step by step if you need it.

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