ONAN Fuel Shut-Off Valve

[Matt Colie]

>
> QUESTIONS:
> 1) How does the shut-off solenoid work? What causes it to close off fuel. (i.e. generator running, valve open; generator shuts down, or not
> running, valve automatically closed?)
> 2) Is the Ground critical? It appears it would be grounded through the piping back through the Fuel Pump.
> 3) Any sealer recommendations on brass elbows to Fuel Pump and elbow to fuel line? Some seepage before, caked saturated dirt around connections.
> 4) Any other issues the "GMC brain trust" may have to check for a 2 Hour dying ONAN.
>
> Clark
> 76 GMC Glenbrook, 455, 6KW ONAN

Clark,

1-The valve opens when the unit is running. Otherwise it is closed.
2-If it has a wire ground, always assume it is important.
3-Any good fuel friendly pipe thread sealant should be good.
4-A shutdown (and quick restart) like that is usually a fuel problem. Check all the lines all the way to the tank. This can be no fun as the part
near the tank is tough to get at.

We had a wonderful tech session at one of the internationals with a guy that worked for Onan on this package....
The fuel solenoid was put in the package for the installations where the fuel tank level can be higher than the carburetor. Ours cannot be. So, if
you think that might be a problem, pull it out.

Matt
--
Matt & Mary Colie - '73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan
OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Twixt A2 and Detroit

 

[john r. lebetski]

Mine has no safety solenoid and never spilled over due to tank position as Matt mentioned. It might be " refigerator door light syndrome". Open the
drawer to work on it runs fine. Push it in and after a while it falters. The fuel line from nipple on floor of non moving case to pump can PARTIALLY
kink when you slide it in. Originally there was a screen door spring to dress the hose but those have rotted to dust. The kink in tygon line is hard
to see when not in kink mode. I replaced mine. Also the line can split at the pump inlet barb but be hidden by the clamp and will suck air.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Ken B]

My thoughts:

If a hose were cracked or leaking between the fuel pump and the carb fuel would be under pressure there and you should see it. This should not cause
an engine shut down but could be a very dangerous fire situation depending on the size of the leak.

If a hose were cracked or leaked between the tank and the fuel pump this is on the suction side and could cause your failure.

Some coaches came with the fuel shut off solenoids and some did not. On GM upfitted coaches the fuel source was on a separate gas tank port.

On non-GM installations some companies like Coachman got their Onan fuel from a "Tee" off of the rear tank to coach engine fuel line.

This can be a problem in some instances and the shut off valve is a good idea. Here is the scenario. If the line is teed and the Onan carb needle
and seat valve is open then the main engine (455 or 403) can suck all of the fuel and eventually air out of and through the Onan line.

On all coaches, if the Onan needle and seat sticks open, as pressure builds up in the fuel tanks from outside or road heat, gasoline can be forced
through the Onan line and flood the carb and on out of the air filter. It happened to me once and I had gasoline everywhere but luckily no fire.
This incident caused me to install an automatic fire suppression unit in the Onan area.

My point is while I do not have the shut off valve, I think it is a good idea to have one installed.

On your shut downs. I am guessing vapor lock problems. Mine did that when the temp was 100 or more and I used craponol diluted fuel.

My solution was to cover the line feeding the fuel pump and the fuel pump with fire sleeve and reflective aluminum tape.

Ken B.
--
Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana

 

[john r. lebetski]

The inline metal barb/barb filter is standard procedure for shops like Cinnabar, as is one in line up front mid way in flexible line frame to engine.
I can't stress enough that all rubber fuel line is only barricade type. Non E10 type only lasts a few years and drip,drip, drip as it becomes garden
soaker hose. If the charcoal canister system is setup right you should not have pressurized overflowing.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[john r. lebetski]

As far as shut offs. They can become a leak source. Through the rotating seal or just by 2 more leak points at clamps.
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[Jim Hupy]

The more complex the system is, the more failure prone it becomes. K.I.S.S.
is the name of the game. Ask NASA.
Jim Hupy
Salem, Or.

On Sun, Aug 5, 2018, 8:03 AM John R. Lebetski
wrote:

> As far as shut offs. They can become a leak source. Through the rotating
> seal or just by 2 more leak points at clamps.
> --
> John Lebetski
> Woodstock, IL
> 77 Eleganza II
>
>
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[johnny]

You can lose the solenoid in a GMC without problems as noted above.
The 'primer' switch also helps if K3 is becoming flaky.
You might also consider a new oil [pressure switch.
--
76 26' Eleganza(?) with beaucoup mods and add - ons.
Braselton, Ga.
"I forgive them all, save those who hurt the dogs. They must answer to me in hell" - ol Andy, paraphrased