Onan 4000 generator carb issue 

Thanks for the pointers. I got a good tip from a Cummins tech. He said to install a shut off gas valve in line just before it goes into the carb. When you're ready to store for a while, turn off the gas valve, start the gen, and let it run out to empty the bowl. He said you will never have to replace the carb if you do this.

Moving the altitude adjustment valve back and forth like you said fixed my problem! Thank you Thomas!!!

THIS IS HOW I FIXED MINE, IN THE CASE OF.... "I CAN'T START MY GENERATOR" It's has been two years since last time it was running, so I started by checking oil level full at gen dipstick (it won't start if low oil because of sensors) then I checked gasoline more than 1\4 tank in the RV (also safety sensors), sparkplug checked for good spark, also checked the manual reset circuit braker ( to be ON) at front motorhome engine compartment for 12v current to the generator to be able to start it, also cleaned the carburetor and even installed new one but same situation, then checked wires and found some has been chewed like gum by rats at the back of starting switch generator panel so I replaced them, at this time the generator started but stay running only by keep pushing the switch on all the time, so then finally I knew it was internal electrical problem from the engine itself, so I took the generator out from my RV to work in my garage, (I did this by myself with some tools and old Mayan tricks ) lol, it's really heavy for one person. I disassemble the unit at my garage and started by removing the cover, then the cooling fan or flywheel unit (it's 2 items in one) until finally I was at the gen rotor and brushes assembly area and this is what I found: one more wire chewed by filthy rats plus the stinky rat nest in the middle of the generator motor coil, I fixed the wire and sanded the commutator copper contacts where the brushes are sitting becouse they were real duty with old urine from the rats, and of course I got rid off the stinky nest, lol!!! Then I assembled everything back together and... bingo it's runing like a champion!!! For this project materials involved was about $60.00 including an aftermarket new carburetor and an harmonic balancer/steering wheel puller (available at any auto parts for $25.00) to pull the aluminum fan out and (flywheel). Just picture this: (Any gasoline engine run smooth if gasoline and DC current aren't interrupted) so following this important principle you'll always find the problem to be fixed. Also if you have a onan microlite 4000 like mine, don't run it for more than a minute without the cover because you'll cook the engine real fast, also keep the eye on the aluminium fan and your fingers after cranking it in case you missing one or two members...just kidding, lol!!! After testing the gen then I did put the air cooling assembly back and the rest of components including the cover, now it's ready to be installed at my RV. Once the gen was installed back at my motorhome I started it to be tested for electric power but not before flipping the electric switch (on) at the gen starting control panel (sometimes hiding under or around the panel) to transfer power to my RV GFCI main outlet and electric panel as well, my motorhome it's equipped with GFCI so I reset it and tested for green led light indicating power is ready at my main breakers panel, so I turned my main breaker (on) along the others ones but no power was present at my breaker main switch (faulty main braker) so I flipped it many times, sometimes you can make it work again, mine did work, lol!!! I'm happy because everything works now including the ref for cold drinks and AC for this crazy summer, lol! Later I'll buy me a new main braker, for now this is a resurrected generator story that needed to be shared. If this can help eaven one person to save time and $$$ it'll make me more happy, thanks for reading!!!

I want to thank you for saving me $250! I followed your video because my Cummins Onan 4000 rv generator was running poorly. It would run fine for 8 sec then bog down for 2-3 sec. Then ramp back up again for 8 and kept repeating this cycle. Showing me how to use the code it came out to be code 14. Which I found could be many different things. But your last idea of turning that screw under the carb bowl did it! I turned it counter clockwise and fuel came out, I turned it back to close. Did it again and then boom! It just started running normal! Thank you for the tip!!!! The mobile guy wanted $250.00 just need to run the generator about once a month for 1/2 hour to keep the varnish from clogging that up I also heared ethanol free gas will keep,that from happening. Thanks again !

Thank You for that Tip, I tried so many things including removing and cleaning the carburetor, focused on that elevation control jets and it fixed the problem, Thanks again for your help.

THANK U... OH AND DONT LET gas tank get below 1/4...keep it at 1/2

Tried this and it got my generator running…. Thanks!!!

Thankyou so much!!! Your video helped me fix it!!!

Thanks for the video!. I have a Commercial 4,000 that looks slightly different and sits in a horse truck, not a motorhome. The generator has 770 hrs on it and I have only started it once when I first bought it 11 years ago. I've put in new gas, disconected the line from the carburator and tried to get some cleaner in there and blowing into it to force the cleaner into the carburator after removing the spark plug. It chugged a few times but did not start. I have a start/reset button similar to the priming button but there is now sound at all and no light on it so I don't know if that is working. When I put gas directly in the sparkplug hole it fires up and I can see there is a spark so the problem is it's not getting enough fuel. I think the next step will be removing and cleaning the carburator. One thing I wonder is if this version (Onan Commercial 4000) lets the air out of the fuel system automatically or is it done manually?

Did you check to see if the solenoid was stuck closed. Lightly press on the plunger to see if it is stuck. Worked the plunger on mine,put the carburetor back together and it ran fine. it back on

Thank you for the video. My generator is giving me the over crank code. How can I fix this?

No joke, I need to make a video and show everyone how to fix this very simple carburetor when this doesn't work. The hardest part is getting the carb out....and that's not that hard. Did mine this afternoon today. 12-13-20 Save yourself 4-5 hundred bucks by replying to me. Hint.....the problem is where you can see the choke butterfly valve.

wat causes one to just pop back threw the carb wont sstart new plug an carb

Does anyone know why they call these micro quiet? 😂