Onan generator won't stay running

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Jackofalltr8des

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Joined
Jun 11, 2021
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1
Location
Tennessee
Hi everyone,
Hope you're all doing well. I have an issue with my Onan geny I wanted to see if anyone has some insight.
I have a 2001 Holiday Rambler Endeavor class A on a Ford v10 gas chassis with a full take of gas. It has an Onan 5500 Marquis gold gas geny. It has an issue where it runs for about 10-15 minutes then dies. It produces no code (light flashes). I researched known issues, changed air filter, did oil and filter change with no change. I did get a low oil pressure code after oil change. I added a lil oil then it went away.
It doesn't matter what the amount of load is on it. It's always around 10 minutes or so. Any help would be appreciated.
 

Matt_C

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Mar 4, 2019
Posts
489
Location
SE - Mich
Jack,
At 20yo, a lot of problems start with rubber parts. (Care to bet how I know??)
As soon as you can, inspect all the rubber fuel lines. Replace them with fuel line that is specified as Alcohol resistant.
I don't know how accessible it is, but next time it dies, do a quick check for spark. This is also the age when some of the electronic components die. They can die of heat before they die completely.
Matt
 

Kirk

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Oct 30, 2005
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959
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Full-time , Escapee
Matt has suggested exactly what I was about to. The fuel pump on your generator is drawing fuel by vacuum from the tank and that hose has been known to collapse.
 

phil-t

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Jul 10, 2017
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1,137
Location
Ogdensburg, NY
How long b4 it starts back up? Check what it would take to remove the fuel line from the carb and when it fails, remove that line and see if you have fuel while cranking. Like was said, it could be fuel lines or the electric fuel pump. Then it's on to the control board. Flight Systems has a great troubleshooting guide on line.
 

Seon

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Aug 30, 2011
Posts
402
Location
Lake Camanche, CA
I had a similar problem and ended up that the fuel line had a small crack but didn't leak gas.
Replaced said fuel line that cured the problem.
 

Gary RV_Wizard

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Feb 2, 2005
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74,608
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At our Silver Springs FL home
I had a similar problem and ended up that the fuel line had a small crack but didn't leak gas.
The fuel line between genset and coach fuel tank won't leak gas because it is under suction rather than pressure. The fuel pump at the genset sucks gas from the tank, so a bad fuel line lets air leak in rather than fuel leaking out. A pin hole or crack will allow air to creep in slowly, so the genset runs for a while but eventually starves for fuel as more and more air builds up in the carburetor bowl..
 

sc4668

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Apr 18, 2017
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Location
Brooklyn, MI
Quick way to troubleshoot the fuel line. Remove the line from the fuel pump install a fuel line from the pump and place in a can of gas. Start the generator and see what happens. If runs with no problem fuel line from tank to fuel pump is bad. If has the same problem the problem is on the generator.
 

Kirk

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Full-time , Escapee
Remove the line from the fuel pump install a fuel line from the pump and place in a can of gas. Start the generator and see what happens.
A very good troubleshooting tool. I would use some quality rubber fuel hose but with a short hose and a gas can at near the same level as the generator it will not take much vacuum to pull the fuel. Since a generator only burns about 1/2 gallon per hour an ordinary gallon can would be sufficient.
 

NY_Dutch

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Nov 22, 2010
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Where our wheels take us!
A very good troubleshooting tool. I would use some quality rubber fuel hose but with a short hose and a gas can at near the same level as the generator it will not take much vacuum to pull the fuel. Since a generator only burns about 1/2 gallon per hour an ordinary gallon can would be sufficient.
My Onan 5500's fuel pump has no problem pulling fuel from a gas can sitting on the ground.
 
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