btcruzer
missouri
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Joined: 12/06/2007
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Got an Onan 4KW generator giving me fits. It starts and runs fine, then after some time it'll run rough then finally quit, like it ran outa gas. Pressing the prime switch won't run the electric fuel pump and the generator will not start. There is 12V present on the fuel pump battery lead and the grounds have been checked out. The ground lead is on the same terminal as the starter uses. There is no trouble codes flashing.
After some time ( maybe 15 minutes ) the pump can be heard when the prime switch is pressed and the generator will restart. Can these simple little fuel pumps get hot and "lock up" and then cool down and work again? The pump is mounted inside the Onan housing and it gets pretty hot in there. I've removed the pump and ran it to pump gas from a can and right back into the can. Blocking the output of the pump didn't stop it so it seems strong enough.
Label on the pump says not to replace with another pump with more than 1.5 PSI. Haven't found one with less than 2.5 Psi. Read on this board that some have luck with a $40 pump from "MR. Gasket" from the auto parts store.
SUGGESTIONS?
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enblethen
Moses Lake, WA USA
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Joined: 01/05/2005
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Please post model and series numbers.
Gunny357 should be able to help.
It could be a problem with the fuel line between the tank and genset. You could take the pump output line loose and see if it pumps a good stream of fuel. If not it is a fuel supply line collapsing.
Bud
Suzuki XL7 pushing Pace Arrow
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mowermech
Billings, MT
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Joined: 06/28/2003
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How old is the RV? I had an older Class A that had a similar problem. It turned out to be the rubber line at the gas tank had a crack in it, and was allowing the pump to suck air. Eventually the pump would get hot from overwork, and quit. I replaced all the rubber fuel line in the system, and no more problems.
Good luck.
CM1, USN (RET)
'94 Dodge 3500 4X2 CTD, Std. cab, LB, 5 speed, 4.10 LS diff., Jacobs Rambrake, 273,000 Miles
'99 Monaco McKenzie 32' triple slide
'95 Tioga 29H Ford-based Class C
Daily driver: '06 Jeep Liberty CRD
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CloudDriver
New Jersey Shore
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Joined: 10/30/2005
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I had exactly the same problem with the same symptoms with our Onan 4K two months ago. After the gen quit, the fuel pump would not run on prime until it cooled for 15-20 minutes. Then it would run on prime and the gen would run another 10 minutes or so and quit again.
I replaced the pump and no more problems. I called our local RV dealer and they ordered the correct fuel pump from Onan. The part # is on the label on the pump. While I had everything apart, I replaced the fuel filter too.
BTW, the pump is on the inlet side of the fan that blows cooling air over the generator and engine, so it is not exposed to the heat from these items while the fan is operating.
2003 Winnebago Minnie 24F - Ford E-450
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btcruzer
missouri
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Its late and dark so getting the model # will be done tomorrow. The MH is an 05 Gulf Stream. The fuel lines I've seen look to be in good shape, certainly not cracked or brittle. It pumps a good stream when it is working. I've disconnected it from the Carb and get good flow there.
When I've disconnected the fuel line from the inlet side of the filter fuel flows out of the line so I don't suspect blockage or split/airleak.
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btcruzer
missouri
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it looks like cloud driver was replying as I typed. Sounds just like my situation. If original Onan last no longer than this, I won't be replacing it with an Onan part. Just for the heck of it, how much did the replacement pump cost you?
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MNtundraRet
Bloomington, MN
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I did not see this meantioned, so I will ask. Did you check you altitude adjustment setting. It is a small knob with a scale: 0 - 5000 - 10,000 feet. The altitude should be set near you current number of feet over sea level. If the lever is set too far above your current location the motor can overheat and shut down. There is a section in the manual discussing it's use, but they neglected to meantion it in trouble-shooting section. A rather large oversight considering it's importance in keeping the engine running correctly.
Mark
Mark & Jan "Old age & treachery win over youth & enthusiasm"
2003 Fleetwood Jamboree 29
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Dusty R
Charlotte Michigan 48813
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Side comment. I like to run any engine that I'm not going to run again for a while out of gas. So I added a switch to that fuel pump.
Dusty
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Bushey562
Norco, CA
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Joined: 10/18/2005
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Dusty R wrote:Side comment. I like to run any engine that I'm not going to run again for a while out of gas. So I added a switch to that fuel pump.
Dusty
I have always done that too since day 1. I posted that here before and got flamed about the RPMs going crazy while its running out of gas. I have been doing it forever and have never had a carb problem on any small engine. So I will continue to do that because the proof is in the pudding for me. Of course you shouldnt have a load on it while its running out of gas.
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n5tc
Salado, Texas
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Joined: 11/18/2005
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The generator posts a "trouble analysis" code. Check what it says against the list in the owner's manual.
n5tc
Tom and Judith and Yappy Schnauzer Sable
2006 Coach House Platinum 272
Saturn Vue Tow Car
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