How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Hank F. Your Own Question
Hank F.
Hank F., RV tech - emphasis on gensets
Category: RV
Satisfied Customers: 15198
Experience:  RV tech since the beginning of the millenium.
Type Your RV Question Here...
Hank F. is online now
A new question is answered every 9 seconds

I have a onan quiet diesel 10,000 geneator in my motorhome,

Customer Question

I have a onan quiet diesel 10,000 geneator in my motorhome, it had a fuel leak on the 3/8" rubber hose that goes from the fuel line to the top of the engine and appears to be going into the top where the lines go to the injectors. I replaced the entire line(about 3 foot long) that had fuel in it when removed, generator ran fine before replacing line, after putting on new line it would not start, I assumed it has an air lock and not getting fuel, but can find no way to make it work.
Submitted: 12 months ago.
Category: RV
Expert:  Robert replied 12 months ago.

Hi my name is Robert...

Not sure what you have tried, what I might do is loosen the fitting on the fuel filter and then prime the generator with the switch on the generator until you get flow and then tighten up the fitting on the filter and see if it will fire off. I would have a small can under the filter to catch on fuel. You would hold down the control switch to the stop position to get it to prime for at least 30 seconds... Please let me know if you need more help, follow ups are included... Robert

Customer: replied 12 months ago.
Robert, The fuel line I replaced does not go to the fuel filter, there are two fuel lines going into the generator, the one I replaced goes from the incoming fuel,line to the top of the engine ,looks like to the lines to the injectors, when I loosen the line it does not pump any fuel out. I am sure the engine is getting no fuel as it turns over perfect and does not try to fire, leaving me to believe no fuel and air lock.
Expert:  Robert replied 12 months ago.

I agree that it is air bound, I did not know if cracking the filter line and priming would get fuel going. I would say loosen the injector lines and then try priming but I have never had to do that on that model. There is another tech. that comes around that specifically works on these generators, if you would like me to put your question back up for him please let me know... Robert

Customer: replied 12 months ago.
When I loosen the line and hold the switch down to the stop position to prime it does not seem to do anything.
Expert:  Robert replied 12 months ago.

It should be priming, you should hear it as well when the switch is held down, the only other thing you might want to try is crack the injector lines and try priming again until you get flow. IF that does not work please let me know, there is an Onan tech that comes around he might be able to assist.


Customer: replied 12 months ago.
Cannot hear or see anything when holding the switch in the stop position, in the start position I can hear a click but then the engine rolls over and nothing happens. I can crack the lines but find no way to get any fuel through the lines to make it run.
Expert:  Robert replied 12 months ago.


So it appears the issue is it will not prime from the switch when you hold it down to stop (outside switch) it should prime, you would hear some clicking when that is occurring. What I am going to do is put your question back up for other experts. I do not know when another expert will respond, they come and go daily, may not be anything you did wrong as it is required to prime the gen. with the switch after you change the fuel filter or replace a line... Robert

Customer: replied 12 months ago.
I agree, it appears that the prime function on the stop switch does not work, so need to find some way to prime the lines to get it started.
Expert:  Hank F. replied 12 months ago.

Hello, my name is ***** ***** I am going to assist you with this.

If you replaced a rubber line, that is the fuel return - not the supply.

When you press the STOP/PRIME switch and hold it, is the light flashing in the switch? Remember, you have to hold the switch for at least 3 seconds before the fuel pump activates.

Customer: replied 11 months ago.
The light is flashing on the switch and I held it for a minute and can hear nothing running or see and fuel when I crack any of the lines.
Customer: replied 11 months ago.
Ok so I have been referred to 3 techs with no results and have not solved my problem, but you still charge my credit card for services that certainly did nothing to fix the problem. I would like a full refund as you have done nothing but guess as to what to do and none of it worked, most everything you suggested I had already done with no results.
Expert:  Hank F. replied 11 months ago.

Sorry, but I had to work overtime tonight, and I just got home.

You have not been referred to 3 techs. The first expert realized that this was beyond what he can do, and opted out. I then took over.

I work 2 jobs, and help on Just Answer in the evenings. I can not be online 24/7.

Since the pump is not pumping when you press the PRIME switch, you need to go in and see if you accidentally unplugged the fuel pump when you changed that fuel line. Also check the ground wire and make sure it is not broken.

If it is not unplugged, unplug it and test the wire for 12V while pressing the prime button. If it does not have 12V, let me know.

If it does have 12V, try jumping 12V directly to the pump. If it does not run, the pump is bad.