Onan 4000 Generator not quite starting - Probably a fuel issue

The friendliest place on the web for anyone with an RV or an interest in RVing!
If you have answers, please help by responding to the unanswered posts.
See posts with no answers
My generator ran smoothly for at least an hour but quit when I was not there. I cannot get it restarted, and it produced no blink code. Since my house battery is shot, I have to start the chassis motor to get juice to the generator starter.

Would the fact that my house battery is toast affect the starting or running of the generator (other than turning the starter over)? I wondered if a depleted battery with a dead cell would have any subtle effect I am missing. The converter must be trying its best to direct power to that battery to charge it.
 
On mine the genset starts off the house battery. From there the genset is on it's own. Any power back to the house batteries is via genset 120V AC and the converter. Even if your house batteries are "dead" and your converter is BTTW trying to bring them up, that represents only a fraction of the power of a 4kW genset. You might see if a new house battery resolves the issue but if it's turning over it'd be my guess it's something other than the battery.

Mark B.
Albuquerque, NM
 
Probably a good idea to verify your fuel level. Gennys are finicky about how much gas there is in the tank. Somewhere between 1/4 to 1/2, minimum.
 
The tank was at 1/2 and I just added fuel stabilizer and topped it off.

I also think running out of fuel produces a blink code.
 
Tiercel said:
My generator ran smoothly for at least an hour but quit
Click to expand...
I will take a guess that you're running too rich. Confirm by looking at the bottom of the spark plug.

When fully warmed up, it requires a leaner gas/air mixture. How long it will run rich will depend on how rich it is as well as how hot the genny is.

You probably only need to go a little leaner.

-Don- Gallup, NM
 
Tiercel said:
Don, do you mean by adjusting to a higher altitude? I still have not touched the spring loaded screw right under the altitude adjustment.
Click to expand...
On the outside of the carb (both the Onan and Chinese carb) there is a knob you can turn that says "1000, 5000, and other such numbers in the thousands. You can turn it to the right (higher number) for a leaner mixture.

-Don- ABQ, NM
 
After installing a new house battery I got back to the generator.

It took only a few minutes of the gen running for about 15 second intervals before I found that manually pushing the linkage arm to open the intake flap kept it running. I had to hold the choke open for a few minutes until the engine warmed and the linkage kept it open automatically.

I ran it for a couple hours under about a 2,400 watt load. It restarted with no issues while warm. I will try it tomorrow cold. If I have to hold the choke open for a couple minutes I can deal with that in the short term until I figure out how to resolve the problem.
 
Last edited:
DonTom said:
Now it sounds like you're running too rich even from a cold start. -Don- ABQ, NM
Click to expand...
As you know the automatic choke is controlled by temperature. I am not sure how to adjust that. It looks like the thermal control is in the exhaust and connects to the choke via the linkage. Maybe it is only an issue because it is late in the year when the temperature is down just enough to pull the choke closed when it is not really cold enough to need it (although I doubt it). I probably won't get this fully resolved before next spring.
 
Last edited:
Thanks, Don, I will definitely read through that link. I did go down this morning (i37 degrees) and it kicked right off. After it ran for about 2 minutes it started smoking some and threatened to choke down. I just pushed the choke open for about a minute then let go. It surged for another couple of minutes then ran smoothly for an hour. I think just running it has helped

I have noticed that during the surging the choke linkage is constantly moving back and forth until it heats up enough to pull the choke fully open.

Considering where I was with this MH 4 months ago, I am pretty satisfied.

PS: has anyone cleaned out the spark arrester? Mine has two square-head bolts impossible to get to with an adjustable wrench. (all I had near me at the time).
 
The generator not staying running after release of the start witch is almost always the voltage regulator in the generator. Once the control sees 120 output it will continue to run. If not...engine off. Unless you hold the switch in start. You wont have power inside coach though.

Micro 4k manual...


And for generator troubleshooting locate someone who has a Flight Systems G-man 360 and diagnosing a generator is takes less than 5 min.


I'm seriously considering purchasing one (works package) just to help folks diagnose generator issues. Far too many RV places either throw parts at problem ($$$.$$) or..."Yeah we'll pull the generator...blah...blah...$$$$.$$+" (when it often times doesn't need pulling). I figure $$.XX - $$.XX to just diagnose an issue saves the owner money and offers a peace of mind. At that point the owner can decide to fix himself and/or have someone do it. Either way you now know specifically what needs replacing and not risk being a victim of a shop scamming you.
 
Last edited:
All good points, but in my case, it was apparently the carburetor/fuel system. Once I changed the carb and did a little tweaking, it ran fine with good output.
 
You must log in or register to reply here.

Latest posts

Members online

Total: 992 (members: 26, guests: 966)

Forum statistics

Threads
131,924
Posts
1,387,525
Members
137,674
Latest member
SPK550
Back
Top Bottom