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Cardoctor71
Cardoctor71, ASE Master Technician
Category: RV
Satisfied Customers: 670
Experience:  35 years experience in the automotive and Lt truck repair business, owner Cardoctor LLC Guthrie, OK
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I have an Onan RV QG 4000 EVAP, that would not start. I have

Customer Question

I have an Onan RV QG 4000 EVAP, that would not start. I have not used it in a few months, and although I had Stabil in the tank, the fuel smelled skunky. I dumped all the fuel and replaced with fresh, dumped the carb bowl, and pumped out the fuel line. THe genset will start and run for a while as long as you use the choke to keep it running, then will stop and give you the flashing code for requires service.
Have I ruined the carb?
Submitted: 1 year ago.
Category: RV
Expert:  Cardoctor71 replied 1 year ago.

Most likely the seal or gasket on the bowl did not re seat properly and is sucking vacuum, disassem,ble and reassemble the carb with new gaskets and seals, and the carb should be fine. Please RATE my service a 3 or above, if for some reason you can not PLEASE ASK me another question, I will continue to answer your questions even after the rating is given ,until you are completely satisfied with my answers.

Customer: replied 1 year ago.
These carbs are listed as non-rebuildable and run $300!
Why would gasket not reseat?
Expert:  Cardoctor71 replied 1 year ago.

Just by coincidence, gaskets and seals should always be replaced once removed from a seated position. You can probably obtain new carbs on EBay for $75 each. Otherwise when re eating a seal you should always apply a thin film of oil on the seal and gasket sealant on paper gaskets. Please RATE my service a 3 or above, if for some reason you can not PLEASE ASK me another question, I will continue to answer your questions even after the rating is given ,until you are completely satisfied with my answers.

Customer: replied 1 year ago.
I did not unseat the seals? All I did was shoot carb cleaner into the intake, and into the fuel inlet. The carb has never been removed from the generator, and it runs, but only if you mainpulate the choke.
Expert:  Cardoctor71 replied 1 year ago.

Ok, then you will need to remove the float bowl from the carb and clean the brass pick up inside the float bowl with carb cleaner then lightly oil the o ring seal and reinstall the carb.

Customer: replied 1 year ago.
We are not communicating, you cannot take the carberator apart to remove anything. If the carb is toast, the only option is to replace the entire thing. I have tried carb cleaner through the air and fuel inlets, to include using a suragate tube to flood the bowl with cleaner and still no-go.
Expert:  Cardoctor71 replied 1 year ago.

normally for sales purposes they tell you it can not be taken apart I have personally taken 100's apart, cleaned the pick up of the separated fuel varnish and they worked great. If you want to purchase a new one ,that is your prerogative.

Customer: replied 1 year ago.
we do think it is varnish, not a seal issue?
Customer: replied 1 year ago.
I have been all over the net and there is mention of the control board as well. If it is varnish, nothing I can do with the carb on the unit? Can't believe these things varnish that quickly.
Customer: replied 1 year ago.
you are confident it is varnish? As the unit is still under warranty, I don't want to take it apart and screw that up, but I also don't want to pay someone to come out and look at it if I can fix it.