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Onan Marquis 7000 Dies Under Load

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g4h2o0st:
Hello,

I have a 1991 Pace Arrow with a Onan Marquis 7000 genset.

The Model Number is 7NHMFA26106B and I have several issues, most importantly the generator dies whenever the A/C kicks on.

I have:
-Changed the plugs... the inner plug was badly fouled.
-Changed the oil.
-Changed the oil filter.
-Changed the Onan fuel filter and added a clear, inline filter so I can verify fuel flow.
-Checked the cylinder compression on both cylinders. Both are kicking out 90 psi.

So, I am beginning to think this may be a carburetor issue. I am looking for a carburetor rebuild kit, but am having problems.
I am also considering the control board and governor.

Any ideas would be appreciated.

Gary RV_Wizard:
Carburetion is the usual problem in a gas genset, especially a vintage model like that. The carb on a small engine is hellishly sensitive to invisible plaque & dirt in the tiny passages. Try a Carb cleaner additive, e.g. Seafoam and maybe you will get lucky. If not, rebuild or replace the carb.

You can mix carb cleaner in a gallon fuel container and divert the genset fuel intake to that container.

jubileee:
You usually can find a carb gasket kit on eBay very reasonable. I have the same generator and when mine has had your symptoms, it was ALWAYS the fuel pump. 3 times in 20 years. In my experience, if they run ok under a light load, the carb is ok.

rls7201:
Does the engine hunt for RPM when under load? If so it is lean. I assume you have tried to adjust the the altitude compensator? If you are uncomfortable disassembling and cleaning the carb, a small engine shop may be able to help.

cgmartin:
Seam Foam is your best friend. Do as Gary suggested.

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