Onan 4ky generator problems

[dennisl]

I have an older Jayco Class C with an Onan 4k generator. Ran it yesterday for about 30 minutes with house ac on. Ran great and then suddenly cut off and would not restart. I pulled the fuel line off at the carb and cranked it for several seconds - no fuel getting to the carb. Today I installed a new fuel pump with no improvement. I then disconnected the fuel line at the fuel filter and attached a short piece of fuel line there with the other end dipped into a small container of gas. Ran great so I suppose that means the fuel filter, fuel pump and carb are not the problem. I guess tomorrow I will drag my ancient carcass underneath to trace the fuel line back to the tank. Anyone here have any other suggestions as to what it might be. Oil level seems to be ok and mh gas tank is over half full. Any advice or suggestions much appreciated.

 

[dennisl]

I have an older Jayco Class C with an Onan 4k generator. Ran it yesterday for about 30 minutes with house ac on. Ran great and then suddenly cut off and would not restart. I pulled the fuel line off at the carb and cranked it for several seconds - no fuel getting to the carb. Today I installed a new fuel pump with no improvement. I then disconnected the fuel line at the fuel filter and attached a short piece of fuel line there with the other end dipped into a small container of gas. Ran great so I suppose that means the fuel filter, fuel pump and carb are not the problem. I guess tomorrow I will drag my ancient carcass underneath to trace the fuel line back to the tank. Anyone here have any other suggestions as to what it might be. Oil level seems to be ok and mh gas tank is over half full. Any advice or suggestions much appreciated.

 

[dennisl]

One thing I forgot to ask about. After installing the new pump I primed the pump for several seconds on a few occasions. Shouldn't a new pump be able to suck fuel thru an empty fuel line all the way from the gas tank to the generator?

 

[Rollin Ollen]

I have an older Jayco Class C with an Onan 4k generator. Ran it yesterday for about 30 minutes with house ac on. Ran great and then suddenly cut off and would not restart. I pulled the fuel line off at the carb and cranked it for several seconds - no fuel getting to the carb. Today I installed a new fuel pump with no improvement. I then disconnected the fuel line at the fuel filter and attached a short piece of fuel line there with the other end dipped into a small container of gas. Ran great so I suppose that means the fuel filter, fuel pump and carb are not the problem. I guess tomorrow I will drag my ancient carcass underneath to trace the fuel line back to the tank. Anyone here have any other suggestions as to what it might be. Oil level seems to be ok and mh gas tank is over half full. Any advice or suggestions much appreciated.

How much fuel is in your tank? Most setups will not allow the Genset to access fuel if the tank is less than a 1/4 full.

Darrell

 

[rv4travlin]

I have the same problem with the 4k onan on our class C. Plenty of fuel getting to the carb, but after 30 - 45 minutes, the generator shuts off. From what I've read, it's probably an over heating thing.

 

[dennisl]

How much fuel is in your tank? Most setups will not allow the Genset to access fuel if the tank is less than a 1/4 full.

Darrell

As stated above, the motor home fuel tank is over half full. Don't think that is the problem.

 

[dennisl]

I have the same problem with the 4k onan on our class C. Plenty of fuel getting to the carb, but after 30 - 45 minutes, the generator shuts off. From what I've read, it's probably an over heating thing.

As stated above, NO fuel is getting to the carb.

 

[Richpatty]

One thing I forgot to ask about. After installing the new pump I primed the pump for several seconds on a few occasions. Shouldn't a new pump be able to suck fuel thru an empty fuel line all the way from the gas tank to the generator?

It should be able to pull the fuel. When I had a gas MH, I had the fuel pump fail and the symptoms were that it would run, then quit. But once I replaced the pump, and cranked it a bit, it did start.

But from what you are saying, the new pump appears to be working? I would be curious if there is a problem with the line. Puzzling.

Maybe an issue with where the line goes into the tank?

 

[dennisl]

It should be able to pull the fuel. When I had a gas MH, I had the fuel pump fail and the symptoms were that it would run, then quit. But once I replaced the pump, and cranked it a bit, it did start.

But from what you are saying, the new pump appears to be working? I would be curious if there is a problem with the line. Puzzling.

Maybe an issue with where the line goes into the tank?

I think you are probably right. My next step is to reluctantly go underneath and trace the line from the tank to the genny. We have a lot of squirrels and chipmunks around here so a chewed line would not surprise me. Just hope the problem is one I can get to. We will see how it goes. Thanks

 

[rv4travlin]

As stated above, NO fuel is getting to the carb.

Well, you ran it yesterday for about 30 minutes with house ac on. So I thought fuel would be getting to the carb........

 

[dennisl]

Well, you ran it yesterday for about 30 minutes with house ac on. So I thought fuel would be getting to the carb........

Sorry for the confusion. I ran it with the ac on Before it stopped running. It ran great until it stopped running on its own and then it wouldn’t start again. That’s when I found out no gas was getting to the carb.

 

[NWIP]

Your first pump may not be bad, I would test by connecting to 12v source. Secondly since you were able to run generator from a secondary fuel source I would suspect the fuel line from the tank or a secondary fuel filter from the tank. Fuel lines with today’s ethanol tend to deteriorate inside leading to clogging filters or collapsing the fuel line.

 

[dennisl]

Sorry for the confusion. When I ran it yesterday with the ac on, it ran great. But then it cut off for no reason and would not start back up. That is when I checked the fuel line at the carb and at that time there was no fuel getting to the carb.

 

[newmarokie]

Try the easy stuff first. Loosen the cap on your fuel tank and see if it works. The vent line to your fuel tank could be stopped up. It would take a bit for the tank to pull enough vacuum to stop the flow of fuel to the genny. The next thing would be to take the fuel line loose at the point you connected the temporary hose to and try to back flush the fuel line. Make sure the fuel cap is off for that.

 

[dennisl]

Well I think the problem is solved. When I crawled under the beast this afternoon, I traced the fuel line from the fuel filter back toward the tank. I then discovered a break in the line over the back axle. I cut out the bad part and spliced the line back together with a barbed metal fitting designed to join the pieces together. Hooked everything back up and it ran for about 30 minutes under load with no problem. As someone mentioned earlier, I probably did not need a new pump, so I will just save the old one in case I need one. My main reason for getting a new pump was hoping it would work and prevent me from going under the RV. At 77 years old and 240 lbs it ain't easy!! What I should have done when I saw no gas to the carb was hook up a short line to a small amount of gas BEFORE installing the new pump. Hopefully someone will learn from my mistake and save themselves a lot of trouble. Thanks for all the responses.

 

[Richpatty]

Great to hear! Glad it was a cheap fix. To be honest, I would have said fuel pump too…as that is a common issue with the Onan gas generators.

Thanks for letting us know the answer!

 

[newmarokie]

Double thumbs up!!!!