Author Topic: Onan BGE 4.0 Spec C dies if I let go of the choke lever  (Read 869 times)

Offline Phlamber

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  • Posts: 4
  • Member since: 2016
  • I own: a Motor Home
  • Year: 1978
  • Make: Fleetwood
  • Model: Pace Arrow
  • Chassis: Dodge
  • Engine: 440-8
I have been working on my friends Onan that had been messed up by every mechanic in town who didn't know what they were doing. Yesterday, I removed the bowl of the carb and cleaned out everything I could. I reassembled it and it ran but was running very rough.
Sometime ago, the choke linkage had ceased to be attached and had started falling off anytime at ran. So, I reattached the linkage and now I can start the generator if I hold the choke lever so that the choke is open. However, if I let go of the lever the choke closes and the generator dies.
Here is a link to the video of the problem: https://drive.google.com/file/d/0B0e1RUX6qmc-WGw2ZXVBUVNMQmM/view?usp=drivesdk

Offline Rickf1985

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  • Posts: 4423
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #1 on: July 28, 2017, 03:39 PM »
Main jet is probably clogged. Or float is set extremly low or the high speed adjustment and low speed adjustments are way,way off. It can be a lot of things but first set the adjustments at baseline and then set the float and finally be sure all the jets and passages are clean. You are not going to be able to this stuff with it mounted on the engine. Is the fuel pump working and is the fuel filter clear?

Offline Phlamber

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  • Posts: 4
  • Member since: 2016
  • I own: a Motor Home
  • Year: 1978
  • Make: Fleetwood
  • Model: Pace Arrow
  • Chassis: Dodge
  • Engine: 440-8
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #2 on: July 28, 2017, 03:53 PM »
The fuel pump is working fine. I couldn't, for the life of me, figure out how to get to the fuel filter. I've been running a gas/Seafoam mixture through it, when it runs.
I tried my little heart out yesterday, in an attempt to get the carb off of the gen. To no avail.
There are two nuts that seem to be on the main bolts which mount the carb to the engine. I just couldn't get any wrenches to make any headway on the rear one. The front one I got all the way loose, but then had no room to actually remove it.

Offline Rickf1985

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  • Posts: 4423
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #3 on: July 28, 2017, 05:00 PM »
It has been a while since I did mine but I remember I had to take the lines off around the back of the carburetor so I had better access and then it was not to bad getting it off. I did take the choke and air horn off so I had room to move it. There is no way you can clean out the passages and main jet without taking it off and spraying everything out with carb cleaner. The float is probably set correctly but check it before putting it back together. And looking at your video again the fuel filter is not there, someone took it out and replaced it with a piece of tubing.

Offline M & J

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  • Posts: 1421
  • Member since: 2012
  • I own: a Motor Home
  • Year: 1987
  • Make: Tiffin
  • Model: Allegro
  • Chassis: P-30
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #4 on: July 28, 2017, 08:26 PM »
I know it was easier to remove the carb and the manifold together on our BGE Onan. Then I had full access to remove the carb.
M & J

Offline Rickf1985

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  • Posts: 4423
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #5 on: July 29, 2017, 08:04 AM »
I did mine while it was installed in the generator bay so that was not an option. And getting mine out of the bay is quite a process.

Offline Phlamber

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  • Posts: 4
  • Member since: 2016
  • I own: a Motor Home
  • Year: 1978
  • Make: Fleetwood
  • Model: Pace Arrow
  • Chassis: Dodge
  • Engine: 440-8
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #6 on: August 03, 2017, 03:40 PM »
Okay, I got the carburetor off of the generator and the jets didn't appear to be very fouled at all. Nonetheless, I cleaned the whole thing out with carb cleaner and I'm about to reattach it to the manifold. I have A LOT of Onan manuals, but I can't seem to find what the baseline adjustments are for the screws on this thing.
Do any of y'all know?

Offline Rickf1985

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  • Posts: 4423
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #7 on: August 03, 2017, 03:59 PM »
I don't have them right off the top of my head but they are in the manual. That is where I got them for my Emerald generator. The high speed setting is very critical so you have to get it set right, take your time getting these settings correct and you will probably be good to go. Remember that this has an electric choke so it should stay on by itself for a short time and slowly back off to no choke at all. And do not play with the throttle too much like you were doing before, that is very hard on the voltage regulator. These are not meant to idle.

Offline tmsnyder

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  • Year: 1989
  • Make: Holiday Rambler
  • Model: 30' Aluma-Lite XL
  • Chassis: Chevy P-30
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #8 on: August 03, 2017, 09:33 PM »
Main jet is turn in fully then back out 1-1/4 turns.  BTW I have the choke disconnected on mine, it looks similar to yours but it's 6.5kw.  It's loose, flops around freely.  On highway when I can't manually close the choke, I can start it if I crank a few seconds, then let it rest 10 seconds.  Crank 3 seconds, rest, etc.  It starts on about the 4th try. 


So if your's is dying when the choke is allowed to open, then it seems like it's not getting the fuel it needs to run.  Check the main jet setting above, and check the float level and that the fuel passage to the float needle valve is clear.


You can try running it without the govenor attached too, just hold the throttle by hand.  You should be able to run it at whatever speed you want with the throttle.  Once you have it running good, you can hook up the govenor and make your adjustments on that if needed.

Offline Rickf1985

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  • Posts: 4423
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #9 on: August 04, 2017, 09:47 AM »
Runnig it at low speed is very hard on the voltage regulator because it is trying to maintain 110 volts.

Offline JohnM

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  • Posts: 6
  • Member since: 2017
  • I own: a Motor Home
  • Year: 1987
  • Make: Winnebago
  • Model: Elandan
  • Chassis: GMC
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #10 on: December 09, 2017, 09:58 PM »
The one I worked on had the 'put jack under the front edge, jack up, loosen bolts, remove bolts along front and right side (rear of generator), lower jack to lower genset.' kind. [Instead of a slide-out]


You need a stubby 3/8's box/open wrench I believe. Lowe's had them on sale for $2.50. The back bolt you remove the far head, the bolt not the nut. The nut is fused onto a piece of metal bracket, and does not turn.


The other linkages and vacuum hose you'll figure out, I won't mention them.


After removing the Nikki carb (brand), and airfilter assembly, separate the air filter assembly from the carb.


Remove the bowl.


Remove the oring for the bowl, the float and the neoprene valve. I think that gets rid of anything that can go bad in carb dip.


Dip it overnight in Berryman's dip. It's a 1 gallon container for ~$20 at wallyworld.


The green paint will come off. There are also an M and S passage you should be able to remove the very tight Philips#2 screws and clean them out.


I had to dip mine twice, the second time dealing with the M and S passages also.


Nikki's get clogged very easy (on onan and other equipment of that period). DO NOT RUN ETHANOL. Or at least use Lucas Oil's Ethanol Additive (in addition to their regular fuel additive) with a high octane (91 type) fuel. The top octane fuels at the pump have better detergents.


I find the 454 Carb type engine runs fine on 87/85.5 junk with Lucas Oil fuel additive.


However, that genset is clog city if you don't run it once a month, and use good fuel.


The Atwood propane hot water heater had paper thin fiberglass insulation, and was inefficient, plus it would only run for 5 minutes then quit, so I removed it when remodeling the RV. It left a nice cavity, where under the bed I placed a L shaped partition, and a 6 Gallon Atwood boat fuel tank sits where the HW tank used to, supplying better fuel to the genset.


It purrs like a kitty now.


Does the one you are working on now, have points?

Offline Rickf1985

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  • Posts: 4423
  • Member since: 2013
  • I own: a Motor Home
  • Year: 1989
  • Make: Winnebago
  • Model: Chieftain
  • Chassis: Chevy
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #11 on: December 10, 2017, 08:09 AM »
That is an older post but I thought I would point something out. You mention running special gas in it and running regular gas in the engine. That would require building a separate fuel tank for the generator. The generator runs off of the same tank as the engine and to run the motor home on the gas mixture you were mentioning for the genny would be rather expensive at 6 MPG!!!

Offline JohnM

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  • Posts: 6
  • Member since: 2017
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  • Year: 1987
  • Make: Winnebago
  • Model: Elandan
  • Chassis: GMC
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #12 on: January 11, 2018, 05:07 PM »
To answer your statement Rick,


91 octane ethanol free is used for the ONAN Genset on it's own tank, a 6-gallon Atwood boat tank.


The highest premium at the pump. Better detergents and no ethanol in premium usually. The RV motor runs 87 octane.


I add lucasoil to both. Lucas ethanol treatment to the separate Atwood genset tank if the 91 contains ethanol.


The void left by the ATWOOD hotwater tank makes room to build an L-shaped wall and insulate it, so the pocket under the bed where the HW tank used to be, is a corner cut-out, vented to the outside through the existing HW heater hatch.


There is the exact amount of depth for a 6-qallon Atwood boat tank. It's not a ventilated gas tank. The gas line is standard pressurized fuel line, the barb on the atwood and the intake barb on the pump are the same size. It's also the same size fuel line as what runs from the RV tank.


Pinch the RV gas tank line over and clamp it.


Run the line from the Atwood tank through a (I think about 6" long) 1/2" pipe nipple inserted in the hole where the hot water tank drain used to be. Nipple threads should extend above the carpet, and below the underside. Extra fuel line allows the tank to be pulled out, enough to access the fill cap and be filled normally at the gas station pump. Once the tank is set down in, it's a snug fit. A padlock on the hw heater access panel latch ensures the latch stays closed.[/size]


Where the new fuel line emerges out the bottom of the floor of the RV, just in front of the Genset, add an inline shutoff (the briggs & stratton kind) and an inline fuel filter, then run it to your pump.


To cycle the genset, turn on the fuel valve. Start it. Run it per normal exercise. Turn off the fuel before shutting off the genset, let it idle for a few minutes then press Stop. This drains the bowl some so the jet isn't sitting in gasoline, keeping it residue free.

Offline Froggy1936

  • 12 year member
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  • Year: 1977
  • Make: Winnebago
  • Model: Minnie Winnie
  • Chassis: Chevy G30
  • Engine: 5.7 1995
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #13 on: January 11, 2018, 07:25 PM »
That is a federal law NO NO.  !-! Putting a fuel tank inside the living quarters , There is the danger of a leak allowing fuel to run the length of the R/V, Allowing fumes to reach pilot lights . But if that does happen (dont forget being hit by a big rig causing a leak)  You most likely will not survive the explosion ! :(  It is better to run the genny off the main tank ,with a good filter . With a fuel shut off valve that can be turned off allowing the carburator to completely empty , Make shure that all loads are off or the voltage regulator will become toast ! Frank
The Journey is the REWARD !

Offline JohnM

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  • Posts: 6
  • Member since: 2017
  • I own: a Motor Home
  • Year: 1987
  • Make: Winnebago
  • Model: Elandan
  • Chassis: GMC
  • Engine: 454
Re: Onan BGE 4.0 Spec C dies if I let go of the choke lever
« Reply #14 on: January 13, 2018, 01:51 PM »
Brand new federally-rated fuel tank.


Small fuel amounts would ventilate to outside, and it's an unventilated tank.


RV would have to be involved in a very catastrophic crash to have that fuel tank damaged enough to leak.
If that happened, the RV would be a total loss anyway.

 

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