Generator

I prime for 60 seconds EVERY time I start the generator, timed with my wristwatch. You can not over prime. The gas just cycles back into the fuel tank, or stops getting pulled from the fuel tank depending on how your fuel system is plumbed.

Even priming the engine, it takes me about 4 attempts to start my generator. I crank it for about 5 seconds, then stop, and repeat (the starting, not the priming).

Running your generator for 2 hours every month under at least 50% load (as Cummins/ONAN recommends) will prevent fuel varnishing in the generator. ONAN says it is better to do 2 hours once a month than 30 minutes a week.

mgirardo wrote:

If you aren't able to exercise the generator once a month, then look into a fuel stabilizer to keep the generator's motor from varnishing.

Even if you DO run BOTH engines once a month, fuel stabilizer should be used for storage more than a month.

THEN....during your active camping season, give it a dose of carb cleaner when the gas in the tank will be used up fairly soon.
Two cans of Berrymans B12 Chemtool is about right for 50 gallons.

gja1000 wrote:
Should you really hold the start button for 30 seconds?

No but you really should prime it better than you have been doing.
5 seconds will not be enough if it has been off for more than a few hours. You can not over-prime; if everything is working right, the prime pump will stop when it needs to.

So.....hold that prime button down at least 15 seconds if it ran within the last few days and the full 30 if it has been 30 days.

And it might be a good idea to fill the main tank because some owners have found that the low fuel cutoff on theirs is way higher than it is supposed to be.

A healthy dose of a good carb cleaner in the main tank would be a good idea too.

gja1000 wrote:
Do you all run a tank of gas through your motor home every month? If I have to, then of course I will.

Our motorhome is a few months shy of 7.5 years old. The generator has about 200 hours on it. I try to exercise the generator every month for about 30 minutes. Sometimes I put a load on it, sometimes I don't. At the very least, I usually put the A/C Fan on and turn on all the lights, so the Converter/Charges goes into boost mode. If it is the summer, I'll put the A/C on if its the winter, I'll put the furnace on.

Our Motorhome has a 55 gallon fuel tank. The generator burns about 1/2 gallon of fuel per hour. The generator cuts off when the tank has about 14 gallons left in it. So it would take about 82 hours to burn through the motorhome's fuel tank. I'm not running the generator for 3 days to exercise it. Our manual for the same generator says exercise it from 1 hour a month at half load.

If you aren't able to exercise the generator once a month, then look into a fuel stabilizer to keep the generator's motor from varnishing.

-Michael

The fuel pump is electric and you can add a switch to the wire going to the pump, and then turn it off while the generator is running. Then the carb will run out of gas.
I did this to our '03 mh, ti work very well.

Dusty

You would think the generator people would have a fuel shutoff mechanism which would allow no fuel left in the carb to prevent this problem. I see these posts all the time.

When I put my lawn mower and snowblower away for the season, I run them and then while still running, I turn the fuel flow switch to off and let it run until it stops due to fuel starvation. Never have had a fuel related problem.

gja1000 wrote:
(1)...i've been reading about fuel varnishing... (1)Do any of you use a fuel preservative and stabilizer?

(1) I believe our ONAN is on its THIRD carburetor. The people we bought our coach from had the carb replaced shortly before we bought it. Then took it home and parked it till we came to look at it. Wouldn't run. I was sure I could get it running OK but couldn't. Replaced carb, so that would make three that I know of.

(2) Yes!!! I add StaBil to every gallon of gas that does into our coach, and I still "exercise" the genset monthly. Not only do I not want to change the carb again... I also want the RV ready to do its second function. Function ONE is weekend or vacation cottage. Function TWO is Escape Module for storms, evacuations, power outages, etc.

If yours has been running, it's possible you can clean it up by running a cleaner like Berryman in a separate can of gas. Use much more than the label calls for. You'd need to disconnect and plug the line back to the tank, and run another line to the aux gas can, FAR ENOUGH away from the generator's exhaust to be safe. You can try adding a load like A/C and let it run for hours. Others say run it and shut off, allowing the Berryman to work on the varnish then run again. Run, Stop, Repeat...

Others have had luck with taking the fuel line off at the carb, draining the gas, putting a little Berryman in the line, connecting and starting. That'd be a do, do again, do again kind of project.

i've been reading about fuel varnishing, a gummy build up in the generator when the gasoline in the motor home engine sits for a long period of time. The manual says it can happen in as little as 30 days, and that you should run a tank of gas through your motor home each month. Yikes! I'm still working so I won't be out in the motorhome every month. Do you all run a tank of gas through your motor home every month? If I have to, then of course I will.

The manual also says, "one way to prevent fuel varnishing is to treat the contents of the tank supplying fuel to the generator with a fuel preservative and to exercise the set. Cummins Power TM Generation has developed a fuel preservative and stabilizer, OnaFresh, specifically formulated for Cummins Onan generators. We recommend adding this preservative to the fuel, especially on infrequently used RVs." Do any of you use a fuel preservative and stabilizer?

I prime my onan 4K using the switch on the inside of the RV. I hold the switch in the off position until the hours on the indicator appear. That process usually takes 3-4 seconds.

Well, I still can't get the darned thing to start. I filled up with gas and that didn't help. I tried turning the engine on while starting and that didn't help. I tried starting from the generator itself and the only fault code it got was "over cranking". So, I'm at a loss. Guess I'll have to take it in for service. Sigh.