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Genny starts, runs rough and then cleans up

lincster
Explorer
Explorer
Wanted to see what others thought.

Genny just started acting like this.
Fire it up, runs rough for 5-10 min, then cleans up and runs perfect.

I have never let the carb sit for more than 1 month without running gas through it.
Change the plugs/filters etc per the schedule in the owners manual.
In fact, air filter gets changed every 150 hours with the oil and oil filter.
Changed plugs per the manual.

Any ideas?
2022 F350 PSD CC 4X4 Dually to pull 2006 LE3905

Lincsters Truck/Trailer

Lincsters Rail
57 REPLIES 57

lincster
Explorer
Explorer
Thanks Hap.

I will just replace the choke first.
My buddy gave me 3 used carbs to try from.

I won't take the carb apart. Too many folks I have heard from out there that say they are not rebuildable.

I will report back about the choke replacement.
It will be after Prez Day weekend since I'm going to play in a couple of days!!!!!
2022 F350 PSD CC 4X4 Dually to pull 2006 LE3905

Lincsters Truck/Trailer

Lincsters Rail

Hap_Hazard
Explorer
Explorer
lincster,

Sorry to hear you're still having trouble. I agree with trying the replacement carb and choke. However, I'd suggest you use the original carb to practice taking it apart, cleaning and soaking in seafoam, and replacing to see if you can get it to work properly. There are two advantages to this.

1)You become familiar with how simple this carb is to work on.
2) If you get it running properly then you have a spare.

When I did mine (a couple of years ago) I found some gunk in the air passages which soak out with the seafoam and cleaned up with a pipe cleaner. The needle valve cleaned up with a little steel wool. Once done and back on the generator I ran it again and sprayed some seafoam through the carb as it ran. Now that I have the choke working the generator seems to start and run fine.

Good luck,
Hap

lincster
Explorer
Explorer
Agreed. I will just take the whole choke assembly off and put it on my carb.

Oh well. Leaving for the dunes in 4 days so will have to do it after!!!!
2022 F350 PSD CC 4X4 Dually to pull 2006 LE3905

Lincsters Truck/Trailer

Lincsters Rail

dedmiston
Moderator
Moderator
lincster wrote:
Update.

New plugs. Adjusted choke. Tightened same screw as Hap Hazard did.

No dice......

Look like I will get a used carb from my buddy and swap out the choke mechanism next and see how that does.


Bummer. I was expecting success. The new/used carb should be easier anyway.

2014 RAM 3500 Diesel 4x4 Dually long bed. B&W RVK3600 hitch โ€ข 2015 Crossroads Elevation Homestead Toy Hauler ("The Taj Mahauler") โ€ข <\br >Toys:

  • 18 Can Am Maverick x3
  • 05 Yamaha WR450
  • 07 Honda CRF250X
  • 05 Honda CRF230
  • 06 Honda CRF230

lincster
Explorer
Explorer
Update.

New plugs. Adjusted choke. Tightened same screw as Hap Hazard did.

No dice......

Look like I will get a used carb from my buddy and swap out the choke mechanism next and see how that does.
2022 F350 PSD CC 4X4 Dually to pull 2006 LE3905

Lincsters Truck/Trailer

Lincsters Rail

Strabo
Explorer
Explorer
Hap Hazard wrote:
Well hereโ€™s my update to my starting problems, a cheap and quick fix.

The problem: The generator would crank over just fine using the remote interior starter switch. Sometimes it would start fine other times it would start and run for about 15-30 seconds and stall out. Re-cranking would result in a no start (or popping) condition. Once in a while it would restart but not very often. I would have to go outside and remove the cover and hold down the carb linkage during cranking. This would start the unit and it would run fine after that. What a pain!!!
I was due for a major service so I replaced the plugs, changed oil and filter, replaced the air filter, removed and replaced the upper carb fuel filter, and replaced the fuel pump and lower fuel filter. I even checked the fuel flow from the tank. I also changed the carb pull off valve as described above. After all this the same problem continued.

The problem solved: After Baker01โ€™s feedback I checked the choke closer. There is a small Phillips screw located on the end of the shaft for the electric choke valve (coming out of the black plastic housing). This screw is on the outside of the electric choke housing towards the carb. It is wrapped by a silver metal return spring. The simple problem was this screw had come loose and the electric choke shaft couldnโ€™t turn the choke plate inside the carb. I tighten the screw and the problem was solved. No cost and a 10 second repair. It starts every time first time.

Hap


Wow, very nice. Good for you.
04' F350 PSD TB SC FX4 XLT, TH-04' 32' Sandpiper Sport Fifthwheel WB Dual Axle
07' Rhino 686 SS106-ITP-AFE-BRP-T4-CDI-KIBBLEBWHITE-CVT-TSTICH-Ridgid LED LightBar-HID Conversion Kit-LIVEWIRE
04' Honda 250 Sportstrac quad
05' Honda 400 Ranchers quad

Hap_Hazard
Explorer
Explorer
Well hereโ€™s my update to my starting problems, a cheap and quick fix.

The problem: The generator would crank over just fine using the remote interior starter switch. Sometimes it would start fine other times it would start and run for about 15-30 seconds and stall out. Re-cranking would result in a no start (or popping) condition. Once in a while it would restart but not very often. I would have to go outside and remove the cover and hold down the carb linkage during cranking. This would start the unit and it would run fine after that. What a pain!!!
I was due for a major service so I replaced the plugs, changed oil and filter, replaced the air filter, removed and replaced the upper carb fuel filter, and replaced the fuel pump and lower fuel filter. I even checked the fuel flow from the tank. I also changed the carb pull off valve as described above. After all this the same problem continued.

The problem solved: After Baker01โ€™s feedback I checked the choke closer. There is a small Phillips screw located on the end of the shaft for the electric choke valve (coming out of the black plastic housing). This screw is on the outside of the electric choke housing towards the carb. It is wrapped by a silver metal return spring. The simple problem was this screw had come loose and the electric choke shaft couldnโ€™t turn the choke plate inside the carb. I tighten the screw and the problem was solved. No cost and a 10 second repair. It starts every time first time.

Hap

lincster
Explorer
Explorer
Update to the issue.
I adjusted the choke a little and it seemed to help.
But, as soon as the genny gets hot, it runs perfect.
Hard to duplicate this issue without time.
I did pull a plug and they need replaced.
I'm sure that isn't helping my issue.
Will report back later this week after I put new plugs in it and start it cold.
2022 F350 PSD CC 4X4 Dually to pull 2006 LE3905

Lincsters Truck/Trailer

Lincsters Rail

Sam_Spade
Explorer
Explorer
baker01 wrote:

If your choke is open when cold it sounds like it is out of alignment.


OR the internal mechanism that closes it has broken.

When COLD you should feel some spring tension that is trying to close the choke plate. If that's not present, it is WAY out of adjustment.....or more likely the thermal spring is broken.

This is the kind of automatic choke that was used on pretty much ALL gasoline engines for maybe 30 years or more. A high percentage of the springs failed after enough miles/hours; or they corroded badly, because the heating mechanism was a tiny pipe carrying exhaust gasses.
'07 Damon Outlaw 3611
CanAm Spyder in the "trunk"

Hap_Hazard
Explorer
Explorer
Baker01,
Thanks for the information. I was concerned that the electrical voltage might be used to close the choke plate and then open it after starting. Your information resolves that issue.

Hap

baker01
Explorer
Explorer
From the manual

Electric choke assembly and vacuum breaker assembly (Figure
8-10). Conduct the following checks and adjustments
before replacing a carburetor/choke
assembly:
1. Apply 12 VDC across the heater terminals. The
choke should open fully in 2 to 3 minutes.
2. Check the heater alignment marks and realign
if out of alignment. The choke should be closed
at temperatures below 70ยฐ F (21ยฐ C). It may be
partly open above 70ยฐ F (21ยฐ C), but should
close almost completely when vibrated (engine
cranked).

If your choke is open when cold it sounds like it is out of alignment. You should be able to loosen the three screws on the choke to adjust it.
Dusty & Mikki
Sirverado 3500 Dually 4x4
2019 Fuzion 369
2018 XPT
2006 Honda CRF450X
2006 Rhino 660
Harley FXSTC

Hap_Hazard
Explorer
Explorer
Hi Again Everyone,

I Havenโ€™t posted in a while but I follow almost daily to see what everyone is up to. Once again I get to ask for help and know the answer is here within our ranks.

My Onan Gold Marquis 5500 HGJAB has a starting issue also. My unit has new plugs, oil & filter serviced, new air cleaner, replacement fuel filter adapter on the carb, new carb pull off diaphragm and new fuel pump & filter down below. The unit has always had Stabil in the tanks during storage, its run regularly when not in use, and Iโ€™ve run Seafoam through the carb.

The unit will not start using the remote (inside the RV) rocker switch. It turns over fine but wonโ€™t fire. If I go outside and remove the gen cover and air filter I find the choke plate fully open. I can prime and manually close the choke plate and the unit fires up and runs like new. It appears the electrical choke is not operating. Iโ€™ve sprayed all spring, levers, and connectors and everything appears to move freely.

Questions:
1)Is there a test for the electric choke? What is the voltage at the two terminals that connect to the choke? Is there a test for the internals of the choke (maybe an ohm test)?

2)Are there any other suggestions or test I should try?

3)Does anyone have a part number for the electric choke on this unit?

Thanks in advance again for your help,
Hap

lincster
Explorer
Explorer
Another update.
Stopped by storage yesterday and tried it again.
Still same issue.

I have a buddy that works on these things out of his house.
He said to try and loosen up the 3 screws on the choke spring housing thing a ma bob..... and turn the spring to help move the butterfly.
I figure worth a shot.

If not, he has 10 old carbs from past customers sitting in his garage!!!
He will give me another carb and I can take parts off of that!!!!

Also, the choke vacuum module is a heck of a lot cheaper than a whole new carb.
2022 F350 PSD CC 4X4 Dually to pull 2006 LE3905

Lincsters Truck/Trailer

Lincsters Rail

baker01
Explorer
Explorer
The Onan vacuum pull off is not cheap at $55-70. I tried to match up an automotive/small engine unit and could not find one that would fit. here is a link to a cheap vacuum pump tester http://www.harborfreight.com/brake-bleeder-and-vacuum-pump-kit-69328.html You put vacuum to the canister the arm on the unit should suck in and stay in. if it moves back out you have a hole in the diaphragm
Dusty & Mikki
Sirverado 3500 Dually 4x4
2019 Fuzion 369
2018 XPT
2006 Honda CRF450X
2006 Rhino 660
Harley FXSTC

nuggetthunter
Explorer
Explorer
Part number for a replacemene is:
Vacuum Breaker Kit A043B658 (Old Kit # 170541-1222)