Weird generator problem - surges, stalls, runs great...surges again on start-up

[rgnprof]

My Onan 4000 Emerald Plus BGE, spec J generator ran fine last fall.  I neglected to run it, or treat it during the winter - didn't really think about it as I was trying to fix other stuff.  Anyway, every time I start it up now it surges - fairly rhythmically - for 5, 10 minutes...sometimes it just stalls out but will restart.  Eventually, if I keep trying it will will start to run normally and it seems to help to get it going if the coach is running.  It eventually ran great for more than an hour with the AC and a 1500 watt space heater running.  Shut it off and tried to fire it up again about 2 hours later - did the same surging and finally stalled.  Started the coach and then started up the generator and it ran better for a while, but stalled again.  Stopped the coach and then started it again and it ran great - under load and with no load.

I changed the fuel filter, air filter, oil and filter and used the Onan 4C cleaner in the combustion chamber - none of that has really seemed to help. 

Any ideas?

ryan

 

[PancakeBill]

There is a little control for altitude.  try rotating that.  I had to pop mine off, and put it back on with more movement.  Totally fixed it. 

Initially you can consider old fuel in the line, but you are way beyond that.  You may also want to swap plugs.

 

[Water Dog]

Electric choke could be sticking; Crud in the carb bowl; Cracked fuel hose; Or coroded or loose 12 volt igniton wire.

 

[rhmahoney]

Is it gas or diesel?

If gas suspect varnish in carburetor.

 

[JIGGS]

Mine was surging and some times would stall. The only thing I did was on a day I had some time . I got it started and let it run with a load on for like four or five hours. It eventually cleaned itself out and has been running fine since then
I think the card had buildup in it since it sat for a while.

 

[tvman44]

Try adding a good dose of SeaFoam to the gasoline and run awhile then let it sit awhile then restart, do that a couple of times hopefully that will clean the gum out of the carb.

 

[rgnprof]

Do I add the Seafoam to the coach gas tank -I guess?  I read somewhere that someone added a good dose of Seafoam to a 5 gallon gas can, disconnected the hose from the coach and ran the generator off of the 5 gal can...I'm not sure exactly how to do it though, at least w/o making a huge mess.

It is a gas generator, but I have no idea how to test the choke to see if it's sticking and I guess I will have to pull the carb if all else fails...trouble is, I'm not sure I can find a gasket/rebuild kit to get it all back together. 

I think I will try the Seafoam and let it run for a good long time - see what happens.

 

[boatbuilder]

Seafoam is also available in an aerosol form under the name Deep Creep.  It works wonders as a penetrating spray as well as carb cleaning and carbon removal.  You take off the air cleaner and with the generator running spray it in the carb until the generator either stalls out or bogs down and shut it off.  Let it sit for a while and then start it back up.  It will run lousy for a little while until all the junk is blown out.  If you are going to change the spark plugs wait until after you treat the engine so you don't foul the new plugs.

 

[rgnprof]

I used this stuff purchased from the local Cummins place - http://www.rvwholesalers.com/catalog/onan-4c-carb-cleaner-48-2120.html - and the instructions say to spray the last ounce in real fast until the genny dies.  I could never get my generator to stall out using this stuff???  And, the thing seemed to run just fine with the air cleaner stuff off...

ryan

 

[tvman44]

This method also works very well, I saved my leaf blower like that and all I took off was the air cleaner to do it.  Yes you put the SeaFoam in the gas tank that supplies the ginny.  SeaFoam also sells http://www.seafoamsales.com/sea-foam-spray.html SeaFoam Spray which is what I used.

Seafoam is also available in an aerosol form under the name Deep Creep.  It works wonders as a penetrating spray as well as carb cleaning and carbon removal.  You take off the air cleaner and with the generator running spray it in the carb until the generator either stalls out or bogs down and shut it off.  Let it sit for a while and then start it back up.  It will run lousy for a little while until all the junk is blown out.  If you are going to change the spark plugs wait until after you treat the engine so you don't foul the new plugs.

 

[Water Dog]

I could never get my generator to stall out using this stuff???  And, the thing seemed to run just fine with the air cleaner stuff off...

ryan

If it runs fine without the air cleaner, and you said you have replaced the filter, that is an indication that it might be running on the rich side (you take the air cleaner off and it gets more air)....be sure that your choke linkage is free and isn't binding on the air cleaner.

 

[PancakeBill]

If running rich, look agan for the altitude knob.  It may say rich/lean, then turn towards lean.  If it is at end of rotation, pop it off put back on wo it will turn more.  The knob limits the amount you can turn.  so if turned all the way to right, put back on with about 1/4 turn to go.  then move to lean.  This is the advice I received from a generator tech and worked perfect!