Onan 4000 MicroQuiet Generator Quit

[Jay1967]

While getting our RV ready for a long trip to the northwest, I started the generator to run it for a while, it's a Model # 4KYFA26100K. I've had the RV 5 years and always exercised the gen every 2-3 weeks for 30-45 min. with a load. It has 703.7 hours. Yesterday it quit after 13-15 min. of running. I restarted and it did the same. So I start replacing cheaper parts first. New air filter, plug gaped at .025, gas filter. Started it, same thing, it quit after 13-15 min. I removed air filter and started the generator and sprayed engine starting fluid into the carb when it tried to quit, it died anyway ???. Gas lines look new. So now I think I'm going to have to take a bigger bite and go for the Carb replacement :'(. I've read all the posts on generators here and watched UTube videos, so I think that's my problem.  But I just wanted to check in and see if there is anything I'm missing ???. All help appreciated .         

 

[wackymac]

Mine was doing the same thing and it was a bad fuel pump.  Pull the fuel line off of the carb, point it in a container and push the start switch like you are trying to prime it and see how much gas comes out.  You might have to run the pump for a while to see if it quits.

 

[jubileee]

Agree with wacky. It's nearly always the fuel pump when they run 10-20 minutes then die. Been through it twice with my Onan and three or four times with friends Onans.

 

[Jay1967]

Thanks for replying Wackymac. I just tried that and getting plenty of gas when holding the start button down. When we got back from our last trip in July, I forgot to add a gas Stabilizer to the gas tank like I usually do. Costly mistake if its the Carb.

 

[Jay1967]

Jubileee, I had taken the air filter off and started the gen. When it started to quit, I sprayed engine start into the carb and it still quit. If the fuel pump was bad, shouldn't tthe gen have kept running while I was using the engine start? I would lots rather find it's the fuel pump instead of the Carb.

 

[glockholiday]

If it will run fine for 15 minutes then it's not the carb. Is it low on oil, some have a low oil safety shut off.

 

[Jay1967]

It's full of oil Glock, thats one of the first things I checked. I think I'll try a new fuel pump as many have advised. Thanks for responding, all help appreciated.

 

[Rene T]

Could it be vapor lock? Is your fuel line routed near really hot generator parts?  Or does vapor lock only affect the engine from starting?

 

[Mpyre]

Try running from an alternate fuel supply before replacing the fuel pump!  If there is a small crack in the fuel line to the main fuel tank it can let enough air in during low flow operation to prevent the generator from running.  You can just use a gas can as the alternate fuel supply.

 

[gary94]

Not familiar with your particular model but most modern Onan gensets will have a trouble code system that uses a blinking light on the start/stop switch at both locations. After it shuts down by itself you have to count the number of blinks. In your situation it would probably be 3 blinks. When your unit shuts down and the switch is blinking (3 blinks) press the stop/prime once and it should give you the secondary fault code. It should be a series of blinks, pause then another series of blinks. For example one blink, pause, three blinks would be an undervoltage fault.

 

[Jay1967]

Update. Thanks guys for all the help  . I replaced the fuel pump and it runs like a new one. 

 

[thesameguy]

I had a similar experience as you at, I guess, about the same time. Generator was a little tough to start, but would start and run until it suddenly wouldn't. I ruled out the fuel pump for the same reasons you did, and then beat my head against the problem for a full weekend. At some point, with little left to try, I connected the fuel pump to a fuel pressure tester and got 0psi. It had good flow, but generated no pressure. I still wasn't 100% sure I wanted to blame the fuel pump, so I ordered a $13 Hitachi diaphragm pump off Amazon to test. With the new pump, the issue was totally solved. However, I didn't want to trust a $13 pump and ordered a Facet solid state pump for the long haul. That $40 pump is a miracle - it's tiny and quiet! I mounted it under the generator platform to help keep it and the fuel cool and have been very happy with its performance over the last month. The generator starts almost instantly - it's really nice!