Generator hard to start and surges

[arch61726]

I have a onan 4000 watt generator and it is hard to start and when I finally get it started it surges for about 15 to 20 seconds then levels out and runs fine anybody have any suggestions on how to fix this

[CleteNKim]

Maybe some helpful suggestions:

Make sure elevation knob is set to proper elevation. They seem to be pre-set at sea level.
Do not use primer unless the generator runs out of fuel.

Hope that helps you out!

[arch61726]

Thanks if I don't prime it I have to crank on it for a long time I have a toy hauler so the tank is all the way in back and generator is in the front

[mud yapster]

Yes I prime mine also ours is a toy hauler too. I have to prime ours also. Ours is a 5000 and after it fires up it runs smooth so as the other guy posted you might check you altitude adjustment setting. It is on the carburetor looking device also shown in the manual.
FYI our fuel line was crimped off in a few places that runs along the frame under the RV to the gas tank. Ran like you describe until I found the crimps in the lines. Easy fix just has to bend the brackets holding the line to the frame.

[2013leprechaun319dsf]

Surge at beginning is normal from what I hear.


Sent from my iPad using Forest River Forums

[Harkerr]

May be a dirty main jet causing a lean mixture.

[ScottBrownstein]

If you have an Onan prime...use it! My previous Onan didn't have one and it never started on the first try. All the prime does is run the electric fuel pump without running the starter. It will save a lot of wear and tear on the starter and the starter is not designed to run a long time without overheating. Normally the fuel pump runs all the time when the generator is running so running it solo for 15 to 30 seconds before trying to start won't hurt anything. You should be running the genny monthly with a good load for say 15 minutes anyway as Onans are prone to varnishing and clogged jets. Surging can be just the fuel system (carb and pump) getting settled down and the genny getting into regulation with the load applied. Probably a good idea to let it settle down before running the AC since the voltage will surge along with the genny RPM.

[EdnKat]

Always use a fuel stabilizer/extender, Sta-bil, Sea Foam, they clean some and do top cylinder lube.
Sounds like your ''surging'' is an m t fuel line, until the pump fills it. The fuel bleeds back to the tank when left sit for awhile. May want to install a solenoid check valve at the tank.

[mud yapster]

Like EdnKat said always use a fuel stabilizer I use Archoil to treat all my fuel in the Generator, Tow truck, car, tractor and riding mower. Been using it in all my motors for a very long time we use it in our back up generator at the house to preserve the fuel since it doesn't get used often and have never had our fuel go bad or had any fuel related issues. Here's some info on Archoil and no I'm not a dealer for the product I have just been using it for as long as I can remember. A little of it goes a long way. 1 oz. will treat 80 gallons of gas or diesel.
AR6200 Fuel Modification Complex


AR6200 is suitable for use in a broad range of hydrocarbon fuel types including diesel and gasoline.

AR6200 contains a proven organometallic catalyst that improves combustion efficiency to produce a cleaner and more complete fuel burn. This results in a reduction in unburned carbon residue (mainly soot) build-up within the Turbo, EGR, DPF and other post combustion parts. With this reduction in unburned carbons, the available BTU (energy or power) that can be accessed through the combustion process is increased. The engine should experience an improvement in torque and fuel efficiency (MPG). Repair costs should be lowered over time and equipment life extended due to a cleaner running fuel system and engine.



AR6200 also contains a high quality lubricant, dispersant, detergent, demulsifier and anti-corrosion package. The dispersant dissolves difficult to burn sludge within the fuel tank, which if left untreated may eventually plug filters and injectors. The detergent package cleans the entire fuel system while the lubricant and anti-corrosion agent ensures fuel system components, pumps and injectors remain sufficiently lubricated and protected. An active demulsifier protects delicate components by separating excess water from the fuel. AR6200 will preserve most hydrocarbon fuels for up to one year.

FEATURES & BENEFITS

• • Improves combustion efficiency

• • Reduces unburned carbon (soot) in engine

• • 5 to 8% MPG increase on CMB Test (US Diesel)

• • Increases torque

• • Cleans and protects equipment

• • Dissolves sludge and other contaminants

• • Protects the fuel pump and injectors

• • Cleans the fluid system and injectors

• • Protects the fuel tank

• • Removes water from fuel

• • Enables fuel storage for up to one year

APPLICATIONS

• • Automotive
• • Transportation
• • Heavy Equipment
• • Agriculture
• • Marine
• • Motorsport

USAGE & DOSE RATE

• • Suitable for use in a broad range of fuel types including Diesel and Gasoline
• • 1oz treats 80 gallons of Diesel or Gasoline
• • 5ml treats 50L (13 gallons of Diesel or Gasoline)
• • 1oz treats 40 gallons for two stroke fuel

[Jim Schings]

Originally Posted by CleteNKim

Maybe some helpful suggestions:
Make sure elevation knob is set to proper elevation. They seem to be pre-set at sea level. Do not use primer unless the generator runs out of fuel.
Hope that helps you out!

Instructions on my Onan 4K tell me to prime for 10 sec before starting. (Actually, is it a "primer". It says to hold the red start button down until the red light comes on. I figured it was some kind of pre-heater.) (Which I do.) However, it doesn't make much difference it still takes 3 or 4 times to start at 3 or 4 seconds each crank. While I haven't checked the elevation knob, my issues have always been at 400 to 1000 feet above sea level. The air density and/or fuel SG, would hardly matter in that range (if the manufacture set it for sea level). (BTW, my 5K and 7K Onans always started instantly.)

[CleteNKim]

Jim.

I have a 4k Onan in a 2014 Sunseeker. I primed it every time I started it, until the red light came on. It was very hard to start and surged for 15 seconds or so. I went and re-read the manual, and it said only to prime if it ran out of fuel. I also reset the elevation knob to my elevation at the same time. It starts very quick now, and does not surge. Fixed my issue, that is why I posted. Obviously the Onan manuals must be RV specific, as I have heard every prime combination possible on this thread.

[Jim Schings]

Priming like that makes more sense. While my dealer told me to prime until the lamp came on each time I started it, it made no sense to me that you would have to prime any carb unless it sat for weeks (or ran out of fuel).

I did check my elevation knob and it was at 0. However the first increment up from there (about 1/8 turn is labeled 3250 ft.) So I tried to set it for about 1K feet with 1/20th turn? Tried starting with the gen cold and warm. No difference. Takes about 3 or 4 restarts at 3 or 4 sec each before it will continue to run. (However I have no surging and great regulation when it does start. That is why I am not complaining to the dealer. After they work on it, it will probably start and that is all. )

Originally Posted by CleteNKim

Jim.

I have a 4k Onan in a 2014 Sunseeker. I primed it every time I started it, until the red light came on. It was very hard to start and surged for 15 seconds or so. I went and re-read the manual, and it said only to prime if it ran out of fuel. I also reset the elevation knob to my elevation at the same time. It starts very quick now, and does not surge. Fixed my issue, that is why I posted. Obviously the Onan manuals must be RV specific, as I have heard every prime combination possible on this thread.

[Tom48]

[QUOTE=CleteNKim;896669]Jim.

I have a 4k Onan in a 2014 Sunseeker. I primed it every time I started it, until the red light came on. It was very hard to start and surged for 15 seconds or so. I went and re-read the manual, and it said only to prime if it ran out of fuel. I also reset the elevation knob to my elevation at the same time. It starts very quick now, and does not surge. Fixed my issue, that is why I posted. Obviously the Onan manuals must be RV specific, as I have heard every prime combination possible on this thread.[/QUOTE

OR you may be one of the few to read the book.

Yes fuel extender but surging the first few seconds sounds normal to me. When you have trouble is when it keeps surging. When that starts, first put an analog meter on your A/C and see how stable your voltage is. Then a KillAWatt meter is cheapest way to check hz. Should be 60 . If voltage or cycles per second are off oh say below 110v with no load or off more than a couple cycles, I wouldn't use it. Fix it and do not believe "the carburetor is not repairable". With some skill you can get the float bowl off and clean it and clear many obstructions that cause surging. Cycles per second can be that regulated running rpm is off. That can be adjusted too.