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smithrock's avatar
smithrock
Explorer
Sep 23, 2014

Onan 6.5 genset problem

Yes I know this isn't technically an RV issue :B. But I'm looking at a boat with an Onan 6.5 gas generator, problem with the generator is initially it runs fine for 45min or so. Then you shut it off- and it doesn't want to start:h
Sellers are telling me that it's been sitting or the gas is bad and it needs to run through it. I'm thinking it's something else since the boats engines seem run fine off it. If the carb is varnished and gummed up, it's not gonna fix itself It wouldn't run initially if it were gummed up. Any ideas on what to check?
  • smithrock's avatar
    smithrock
    Explorer
    Sep 26, 2014
    TEXAS wrote:
    The blower system is what I am talking about. Some boats had the system. Where nothing would start. Until the blowers had cleared the fumes out.

    On the choke. Make sure the shaft is clean and free to move. It may need a new spring. With age and heat the spring would lose tension. The MCE came along after I stopped working on boats. But from what I remember it is just an updated MCCK. I will take a look at the manual.

    The spring or thermostat number is 153-0554. Should be around eight dollars.


    First off, thank you for your help on this! :B. I will pass this info along- hopefully he'll use it, or at least check it out! I'm unable to work on the boat myself as I do not own it yet.
  • TEXAS's avatar
    TEXAS
    Explorer
    Sep 25, 2014
    The blower system is what I am talking about. Some boats had the system. Where nothing would start. Until the blowers had cleared the fumes out.

    On the choke. Make sure the shaft is clean and free to move. It may need a new spring. With age and heat the spring would lose tension. The MCE came along after I stopped working on boats. But from what I remember it is just an updated MCCK. I will take a look at the manual.

    The spring or thermostat number is 153-0554. Should be around eight dollars.
  • smithrock's avatar
    smithrock
    Explorer
    Sep 25, 2014
    TEXAS wrote:
    I couldn't resist this one.One thing I hate more than anything is a mechanic. Trying to BS his way out of a problem that he can't fix. There is no time delay for restarting a marine unit.Not on the Onan.

    Now does it turn over and not try to start. If so check the choke. I have run into that problem many times on boats. I call it a hot choke. Does not cool off enough for a restart. But after about five minutes it cools off enough to start.

    Does the boat have an active engine room delay system. Turns on fans to clear any fumes that may be present


    not sure, I will check that. Are you referring to a blower like on smaller boats that clears fumes in the bilge?
    I will also look into the choke- thanks for the heads up on that!:)

    What was your fix on that hot choke problem?
  • TEXAS's avatar
    TEXAS
    Explorer
    Sep 25, 2014
    I couldn't resist this one.One thing I hate more than anything is a mechanic. Trying to BS his way out of a problem that he can't fix. There is no time delay for restarting a marine unit.Not on the Onan.

    Now does it turn over and not try to start. If so check the choke. I have run into that problem many times on boats. I call it a hot choke. Does not cool off enough for a restart. But after about five minutes it cools off enough to start.

    Does the boat have an active engine room delay system. Turns on fans to clear any fumes that may be present
  • smithrock's avatar
    smithrock
    Explorer
    Sep 25, 2014
    Yeah, I agree. Not my mechanic. He's gettin all pissed at me because I'm picking apart his work- oh well! Glad I'm not paying him! He did put on a fuel pump, but I believe it's vapor locking- don't understand why he can't figure that out!
  • gunny357's avatar
    gunny357
    Explorer
    Sep 25, 2014
    smithrock wrote:
    Not at the boat now. I do know it's Onan Ensign 6500 It's on a 1991 boat. I'll have to get the serial this weekend. Was there today and ran the genny for a while- it ran fine. But when going to start it back up after running it for a while- it didn't want to start. It had to sit for about 5 min before it would start up again. The mechanic told the broker " those have circuit boards and they are designed not to start up right away after running"." Let it sit for 10 min and it will start up."
    That doesn't sound right to me


    That mechanic is full of the stuff that cats bury in the flower bed.
  • smithrock's avatar
    smithrock
    Explorer
    Sep 25, 2014
    Not at the boat now. I do know it's Onan Ensign 6500 It's on a 1991 boat. I'll have to get the serial this weekend. Was there today and ran the genny for a while- it ran fine. But when going to start it back up after running it for a while- it didn't want to start. It had to sit for about 5 min before it would start up again. The mechanic told the broker " those have circuit boards and they are designed not to start up right away after running"." Let it sit for 10 min and it will start up."
    That doesn't sound right to me
  • gunny357's avatar
    gunny357
    Explorer
    Sep 24, 2014
    Post the complete model/spec/serial number for any meaningful advice.

    Need to know exactly what you have. 6.5 BGA? NH? CCK? All completely different Onan 6.5 gasoline gensets.
  • smithrock's avatar
    smithrock
    Explorer
    Sep 24, 2014
    Good call! I'll check that. I actually had that problem in my 5th wheel

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