Onan, tracking fuel problems

[luke walling]

Hi All,

I got the Onan running good today on a external fuel source.

After blowing out the line with light pressure and the fuel cap removed, I replace the broken clear plastic line, vacuumed up a little fuel, and hooked the coach fuel lines back up.

The amount of fuel I was able to pull was a bit light. I pushed a little fuel back through it with light air pressure and pulled it back down. Helped a little.

But, after the onan empties the pump and carb bowl it spits and sputters-can’t pull enough gas to keep running. It runs fine without the pump and friction fed fuel from above, and with the pump sucking fuel from a gas can.

Fuel lines look good underneath, don’t look that old. The back fuel tank looks to be leaking a fair bit, I can’t tell from where. Top drivers side corner is wet on the bottom.

Any tips from the brain trust for the next day I fiddle with the coach on the fueling the onan front?

Luke

 

[jim miller]

> Fuel lines look good underneath, don’t look that old. The back fuel tank looks to be leaking a fair bit, I can’t tell from where. Top drivers side corner is wet on the bottom.

The GMCnet is replete with owners’ accounts of fuel draw problems due to spongy hoses that have deteriorated due to ethanol in our “modern” fuel. Unless you physically examine the lines and can read something like “30R14” or “Gates Barricade” on them then you should assume they are the old formulation that is attacked by ethanol. A classic symptom is the inability to draw sufficient fuel through them to run the {main engine,onan}. My guess is that you have spongy hoses that are weeping and that is the source of the raw fuel you see in and around the tanks.

I do not know what “friction fed” fuel is - but whatever it is it probably isn’t relevant to this particular problem.

—Jim

Jim Miller
1977 Eleganza
1977 Royale
Hamilton, OH

 

[Ken H.]

Luke,

As Jim Miller sort of implied, if you're fooling with the Onan and other
accessories before dropping the fuel tanks and replacing ALL of the vent
and supply hoses with modern, ethanol-resistant, hoses (and/or PolyArmor
tubing), you're wasting your time. You'll never have a reliable coach
until that task is completed. Sorry.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Mon, Oct 16, 2017 at 7:01 PM, Luke Walling
wrote:

> Hi All,
>
> I got the Onan running good today on a external fuel source.
>
> After blowing out the line with light pressure and the fuel cap removed, I
> replace the broken clear plastic line, vacuumed up a little fuel, and
> hooked the coach fuel lines back up.
>
> The amount of fuel I was able to pull was a bit light. I pushed a little
> fuel back through it with light air pressure and pulled it back down.
> Helped a little.
>
> But, after the onan empties the pump and carb bowl it spits and
> sputters-can’t pull enough gas to keep running. It runs fine without the
> pump and friction fed fuel from above, and with the pump sucking fuel from
> a gas can.
>
> Fuel lines look good underneath, don’t look that old. The back fuel tank
> looks to be leaking a fair bit, I can’t tell from where. Top drivers side
> corner is wet on the bottom.
>
> Any tips from the brain trust for the next day I fiddle with the coach on
> the fueling the onan front?
>
> Luke
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>

 

[terry1]

Drop the tanks...replace all hosery...welcome to the club...gotta do mine, too :?
--
Terry Kelpien

ASE Master Technician

73 Glacier 260

Smithfield, Va.

 

[luke walling]

Given the expense of the roof AC and Generator if they needed to be replaced, it was important for me to make sure these things worked properly before going deeper.

Now.. I shall!

Luke,

As Jim Miller sort of implied, if you're fooling with the Onan and other
accessories before dropping the fuel tanks and replacing ALL of the vent
and supply hoses with modern, ethanol-resistant, hoses (and/or PolyArmor
tubing), you're wasting your time. You'll never have a reliable coach
until that task is completed. Sorry.

Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, Troy-Bilt APU, etc., etc., etc.
www.gmcwipersetc.com

On Mon, Oct 16, 2017 at 7:01 PM, Luke Walling
wrote:

> Hi All,
>
> I got the Onan running good today on a external fuel source.
>
> After blowing out the line with light pressure and the fuel cap removed, I
> replace the broken clear plastic line, vacuumed up a little fuel, and
> hooked the coach fuel lines back up.
>
> The amount of fuel I was able to pull was a bit light. I pushed a little
> fuel back through it with light air pressure and pulled it back down.
> Helped a little.
>
> But, after the onan empties the pump and carb bowl it spits and
> sputters-can’t pull enough gas to keep running. It runs fine without the
> pump and friction fed fuel from above, and with the pump sucking fuel from
> a gas can.
>
> Fuel lines look good underneath, don’t look that old. The back fuel tank
> looks to be leaking a fair bit, I can’t tell from where. Top drivers side
> corner is wet on the bottom.
>
> Any tips from the brain trust for the next day I fiddle with the coach on
> the fueling the onan front?
>
> Luke
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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