Ihave a honda generator with a gx 390 motor volt drops when i put a load on it what could it be

This appears to be relating to an Ingersol Rand Air Compressor rather than anything in the Honda Garden category? Make Model (What is is) in all questions please.

https://www.indiamart.com/proddetail/ingersoll-rand-t30-air-compressor-electric-motor-driven-tank-mounted-compressor-package-15hp-22929260312.html

According to my research is has a 20HP 3-PHASE ELECTRIC MOTOR. There are some other tihings to consider. When you are running this Honda gas engine, you are filling your workshop with deadly carbon monoxide gas.

Your Honda GX-390 is only 11.7 hp (8.7 kW) @ 3,600 rpm, not 20hp so it is doomed to failure. Also, how are you going to get it to cycle on when the tank needs it.

Take your existing electric motor and get it repaired or rewound. Much cheaper option for a safe working environment and doing the job it is meant to.

https://engines.honda.com/models/model-detail/x-large-gx

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No, you just change the oil

• 100 hours - CHG OIL - Oil Change Interval (Every 100 hrs) • 200 hours - SVC - Service Air Filter (Every 200 hrs)

https://www.google.com/search?safe=off&rlz=1C1QJDB_enCA643CA644&sxsrf=ALeKk01MEbbatDBhpHGRXLX2gMZ9ODRUSQ%3A1614030679751&ei=Vyc0YKOYLbuz5NoPw6mfwAs&q=black+max+honda+8125+w%2F6500w+generator+manual

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if the motor engine is working and no power output then you need to check is there any power out from the generator motor directly (not in the power out put box I hope you already checked in there) generator motor coils could have busted due to over loads. so even the engine is rotating the generator it can't produce any volts.

The resistor could be bad or it may have a blown fuse

you have a dingo, ugh
I would suspect a bad pump or wheel motor if the rpms are set correctly and no safety switches are causing it to die...

Clean all the ports and jets with some torch tip cleaners or mechanics wire cut at an angle to be sharp.

Make sur ethe fuel filter is not clogged, or the sreen in the tank.

Also empty the tank and dry it out, then add fresh fuel as gasoline goes bad.

check the valve adjustment

It sounds like the needle in the needle and seat (float bowel) is stuck in an open position. Can you remove the float bowel?

Sometimes you have to lower the air pressure in the tank to allow it to run. The back pressure from the compressed air in the compressor head overcomes the pressure created in the engine at the slow RPMs you are able to pull while attempting to crank it.