Genset keeps dying

[watkins-KEY]

HI all,

Trying to troubleshoot something thats been happening since I bought our Fuzion a few months ago.

The genset runs out of fuel, I confirm by opening the drain on the bottom of the bowl and its dry.

Well... first thing it happened I found a nicked fuel line near the fuel filter that was spraying fuel. I cut the bad part out and reconnected everything. Once i got the system primed (took a while... had about 10 failed start and stops until it finally kept going) and then it was fine.

Went out yesterday to change the oil on the genset (hour meter says 160hrs.. although I call BS on that but oil is cheap)... started genset. Runs for 30 seconds. Dies. Check float bowl... dry.

So figure maybe the fuel sending unit is wrong on the genset tank (says 1/4 tank)... go get 5 gallons of fuel. Same thing. Fires up.. runs for 30seconds and then dies. ... float bowl empty.

If I leave the drain screw open and hold the start switch down to prime the fuel pump kicks on and fuel flows out of the bowl. So I am scratching my head at this point as to what it could be.

The pump primes just fine.. so I am doubtful its that...

Filter?

Onan 5500, in a 2023 Fuzion

 

[JBM3M]

IF the system has a fuel filter check that.

 

[watkins-KEY]

Thanks. I've ordered a new one, should be here tomorrow.

 

[JBM3M]

well that may not be the problem, check it against the new one by blowing through it.

 

[GlasNav]

Check ALL of the fuel line connections between the tank and the engine. Also, if the bowl is removable make sure it is seated correctly on the gasket or O ring.

Is there tank head pressure, (the fuel level higher than the engine when full) or does it have to be lifted all the time?

 

[RJS3791RD]

Good evening. I had an Onan 5500 in my previous rig (2015) that was very sensitive with the fuel filter. It was in a class A motor home and the fuel came from the main tank. I would get one season on the fuel filter and then it would do the same thing, run for short period and shutdown. For what it’s worth, I learned that the fuel pumps can be problematic on the Onan 5500 when it is very hot outside, it would vapor lock.

 

[wiredgeorge]

Most inline fuel filters I know of are directional and will have an arrow showing the direction of flow. In addition, if there is a vent, make sure the vent hose is not kinked or obstructed. Floats won't work without venting and will either puke gas or no gas will flow.

 

[Raptor Dave]

Contact Onan and get it fixed under warranty. (which it still should be under but Onan can verify, but don't wait too long or it will cost you plenty)
Cummins owns Onan so I would start at 1-800-cummins
Don't quote me but I believe the Onan rep told me 2 years parts and labor and the 3rd year was just parts from the date of the gen manufactured.
We had the same thing happening on our brand new 2023 Raptor. It would start up and die after about 5 min to 25 mins and would not restart. Come out the next morning and it would start right up and run for a short time, die and would not start again.
Acted like it was starved for fuel.......AND IT WAS!
This was because there were internal parts in the known defective fuel pump that were falling apart and and plugging things up. After it cooled down and the pieces settled back to the bottom of the fuel bowl is when it would start again.
After speaking with Onan I was told they had bad batch of fuel pumps between a certain set of serial numbers.
Had it not been under warranty it would have cost us approx. $1800.
Because it was under warranty it cost me my time to take it to the Onan dealer and my time to go pick it up after they were done with it in 3 days.
My recommendation is DO NOT take back to the dealer if you bought it new IF you have an authorized Onan dealer that is close by you to drop it off at. It may end up sitting at the dealer for weeks before they do anything.
The guy I spoke with at Onan was very nice, helpful and even found the local Onan dealer for me to contact.
If there is not an Onan service center close to you taking it to the dealer and letting them transfer it may be the way to go but it would be the last resort if it were me.
Over the course of owning a few different RV's I have found that most of the appliances (for lack of a better term) are cover under their own warranties and you are better off to just deal direct with them when possible and leave the sales dealer out of it.
Any more, Lippert owns just about everything that is made and installed on your trailer at the factory. Very helpful and knowledgeable on most all of the companies they own that make the different parts.
Good luck.
Hope this helps.

 

[watkins-KEY]

Replaced fuel filter.. ran great for 20min.. died. Has to be pump at this point

 

[watkins-KEY]

Replaced fuel filter.. ran great for 20min.. died. Has to be pump at this point

Actually.. I was wrong....

Decided to pull the carb bowl... sure enough a bunch of orange rubber pieices in it... Hmm, how did those get in here... so I decided to pull the fuel line off carb and run the primer.... well what do you know.. chunks of this orange rubber crap come flying out.

So then pull the carb.. pull the float and back flush it. Sure enough more of this crap all clogged up in the fuel nipple to the float.

Cleared all out. Running perfect now. Going to call Onan in the morning and see whats up. Maybe defective pump and will give me more debris.

 

[klohma]

Check your fuel pump. I had the same problem with my gen, where it would prime then run for a bit and die. After taking it to the local cummings shop so gen guy could look at it, I asked him how bad it was and he said all was good. When I asked him how long did he let the generator run he stated about 5 minutes. My gen would run anywhere from 5 to 20 minutes then die.

So I finally took the hose, the one from the fuel pump to the carb, off of the fuel pump and hit the prime button. The fuel just barley bubbled out of the fuel pump. Ordered a Chinese knock off for 25 bucks from amazon and put it in, mostly, kept the hose to the carb off and hit the prime button and fuel shot out up to the air filter. Put the hose back on, primed and started the gen. Let it run for about 45 minutes and did not shut down. Stopped and restarted several times with no issues.

Only thing left to do is get a proper fuel pump since the Chinese knock off won't fit, the mounting bracket is a bit too far to the rear
.

 

[Pearce369]

Our 2923 Fuzion 428 had the same issue from day 1, it would run for 5 minutes and shut down! I found a defective fuel pump, motor ran but would shut down. I replaced the pump and fixed the problem!

 

[RJS3791RD]

joining conversation late…..

The fuel pumps are the weak link on these generators. I change my filter every year which is well less than 100 hours. I am on my 3rd fuel pump.

 

[Pearce369]

I forgot to mention when the fuel station circuit board had a recall the tech broke plug n play pins on the board. What that caused was fuel gauges didn't work and the hr meter ran constantly which racked up 600 + hours on the generator before I caught it and the generator had not run an hour but shows it ran over 600. Just another one of the many problems in the new unit. Also good luck on finding a onan (cummings) dealer to work on it! I called 4 numbers for different cummings dealers in FL. And didn't get a call back. Finally found and fixed the issue myself.

 

[Mike Honcho]

Having had a toyhauler since 2008 and experieced the fuel issues I found that running 93 octane or at least the highest you can find is more stable ethanol fuel than the 87. Gen only needs 87 but worth it to us higher cost fuel at least a couple tanks before putting away for your off season. Had the carb issues but also the clogged filter a few times. After a few times you learn quick how to fix in just a few minutes and get it running.

We have ethanol free available so I have been using 90 octane ethanol free. Same cost as 93 ethanol. during season or long trips it is fine to burn 87 or whatever. Just go through a couple tanks of the good (or just better) stuff before leaving sit for long periods.

Our 2021 flooded and was replaced with a 2025 in December. Are there still fuel pump issues in newer generators I should be aware of?

 

[Pearce369]

I would replace the fuel pump mine would run 5 minutes and stop. I tried to get service, camping world told me I had to go to acummings dealer. Called 4 in Florida non returned a call! I purchased a new OEM cummings pump, paid $160 from cummings marine dealer. After that I found the same OEM pump on eBay for less than than the price, so I have a spare in my shop! Search your part number and you will find one or a replacement which supercedes as the replacement.

 

[Pearce369]

eBay price was less than half

 

[oudive]

Had a very similar experience with our 2023 Carbon 338 and Onan 5500. Would start, run and then shut off. Turned out the fuel filter was not tight. The thread lock was coming off and made its way into the fuel bowl. Had to clean out a lot of the orange stuff and once it was cleaned and back together, the 5500 runs smooth as silk.
You can see the thread lock in the attached picture.

 

[TheMays]

Most inline fuel filters I know of are directional and will have an arrow showing the direction of flow. In addition, if there is a vent, make sure the vent hose is not kinked or obstructed. Floats won't work without venting and will either puke gas or no gas will flow.

I have to agree with that. I dealt with issues on my 2020 raptor. As well as my Open Range.

If you open the fuel cap after it stalls do you get a strong vacuum?

Also how many batteries do you have?