Cummins 5500 fuel pump

AZ Attitude · 02-16-2022, 11:51 AM

Good morning

I took my trailer to a repair place for an issue my main room slide and the generator not running after it warmed up (approximately 10 minutes). I could keep the generator running if I held the choke open but the minute that I released the linkage to the solenoid it would die. The shop charged me close to $200 (for the generator) tell me that it was likely the fuel pump as they thought it was only flowing 2 and it should be between 4 and 5. That said they wanted $1300 to replace it and make sure it ran. I see them on EBay and Amazon all the time for $20 to $70 as direct replacements and a Cummins OEM for $150-$170. I mentioned that to the tech they said to only use the Cummins OEM as the have a 'frequency' that has sync with the card and an sensor on the 'flywheel'. My question is has anyone used a non OEM pump and which one? Did it work?

My generator has less than 500 hours on it and I change the oil/oil filter and air filter every 100 hours or year whichever comes first. I replaced the fuel filter and torn down and cleaned the carburetor prior to taking it to the shop and the problem persists.

Thank you for your assistance.

Mike Honcho · 02-16-2022, 05:35 PM

Could be the carb, fuel pump or both. Ethanol ruins everything when sitting. You could buy a brand new Onan carb for I think $300 and a fuel pump for under $100. If you have already cleaned the carb you certainly can change the fuel pump too. And it will run perfect until next time.

The issue with cleaning the carb is that the ethanol gunk build up changes jet sizes and it will never run right. You can change out jets and fiddle cleaning other passages but for 300 bucks I'd rather have the genny running right anytime I need it.

Forgot to add that I only had carb problems but one time the fuel pump clogged up and did need to be replaced.

gearhead · 02-16-2022, 06:23 PM

I noticed our local ambulances at a RV shop 40 miles away. I asked the shop what they were doing with the ambulances. "Working on the generators".
So...you may locate an ambulance service near you and ask were they take theirs for generator work. Those gens have to work every time.

**chuckster57** · 02-16-2022, 07:32 PM

Everything I read says a generic fuel pump will work. I call BS, but will check with my boss tomorrow since he’s attended Onan school.

Sarge332 · 02-27-2022, 07:46 AM

I had the same exact issue with my generator. I ended up changing the fuel pump, filter and did an oil change, spark plugs and air filter all at the same time. It purrs like a kitten now. I bought an extra fuel pump to keep with my rig.
With all that said, I 100% believe it was the fuel pump, but I would replace both the fuel pump and fuel filter at the same time. BTW... my generator had less than 20 hours on it when this happened. I also bought an OEM pump from Amazon. Sorry, I do not remember the exact brand.

**chuckster57** · 02-27-2022, 07:53 AM

Well I asked my boss who is Onan Certified over 30 years ago and even he says BS.

Sarge332 · 02-27-2022, 08:01 AM

Quote:

Originally Posted by chuckster57

Well I asked my boss who is Onan Certified over 30 years ago and even he says BS.

I’m not trying to imply you or your boss are wrong. I’m simply saying that I had what seems to be the exact same issue and after replacing what I did replace, it works great now. My issue could have been a fluke. I really don’t know.

**chuckster57** · 02-27-2022, 08:16 AM

Quote:

Originally Posted by Sarge332

I’m not trying to imply you or your boss are wrong. I’m simply saying that I had what seems to be the exact same issue and after replacing what I did replace, it works great now. My issue could have been a fluke. I really don’t know.

No harm, no insult taken or implied. OP asked if the replacement had to be OEM because of "FLYWHEEL" synching.

Sarge332 · 02-27-2022, 08:27 AM

Quote:

Originally Posted by chuckster57

No harm, no insult taken or implied. OP asked if the replacement had to be OEM because of "FLYWHEEL" synching.

All good. Honestly I missed the flywheel part. I focused on the running for ten min and shutting off. But its an electrically driving pump, not mechanically driving, so I would have a hard time believing 'flywheel synching' would be an issue... BUT, I'm a helicopter mechanic, not a generator mechanic lol. We've owned our RV for a year now. We love it, but its a constant learning curve.

hawghauler · 05-23-2022, 07:19 AM

I've found the best solution to this issue is what us gearheads call a "lift pump" but a 20 dollar Amazon pump splice it in at the tank end ground to frame @ mount pull a power wire through sheath around fuel line and tap into stock pump power supply the fuel pump on the generator in stock confirmation has to pull fuel out of the tank through 30 + feet of 3/8 fuel line and it's working it's *** off to do it soon enough it gets tired and you get the 3 flashes of **** my genny won't run

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