Fuel selector valve inputs

[Stu Rasmussen]

Hi all ~

I have a quick, simple question about the fuel selector valve and
searching the archive gave waaay too many hits.

I think the inputs to my fuel selector valve are reversed. Symptoms
are the coach runs well on a tank the gauge says is 'empty' but
stumbles and dies in classic 'low fuel condition' on the 'full' tank.

The question: Which input connection is which on the valve?

(Asking just in case the 'empty' tank has a couple of quarts of fuel
and the 'full' tank fuel pickup tube is clogged or some other scenario
giving weird results.)

Thanks in advance

Stu

 

[emerystora]

If you blow into the output with the switch in main it will come out one of the input openings. That should be connected to the rear tank (the main tank)

Emery Stora
77 Kingsley
Frederick CO

>
> 
> Hi all ~
>
> I have a quick, simple question about the fuel selector valve and searching the archive gave waaay too many hits.
>
> I think the inputs to my fuel selector valve are reversed. Symptoms are the coach runs well on a tank the gauge says is 'empty' but stumbles and dies in classic 'low fuel condition' on the 'full' tank.
>
> The question: Which input connection is which on the valve?
>
> (Asking just in case the 'empty' tank has a couple of quarts of fuel and the 'full' tank fuel pickup tube is clogged or some other scenario giving weird results.)
>
> Thanks in advance
>
> Stu
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:

 

[Jim Hupy]

The fuel tanks in a GMC have to been the results of a 3 day drunk on the
part of GM Engineering staff. NOTHING IS AS IT SHOULD BE!!
The gages are notoriously inaccurate. The switching valve had to be
a last ditch effort to fix an unsolvable problem.. A common to both tanks,
fill manifold allows fuel to freely transfer between the two tanks,
depending on whether you are going uphill or downhill.
If you tried, I don't think that a worse system could be devised.
What MANY of us do is to fill the tanks completely, note the odometer
reading, drive 250 - 300 miles, and then refill the tanks, all the time
ignoring the fuel gages.
Helps keep your sanity.
Jim Hupy
Salem, Oregon

>
> Hi all ~
>
> I have a quick, simple question about the fuel selector valve and
> searching the archive gave waaay too many hits.
>
> I think the inputs to my fuel selector valve are reversed. Symptoms
> are the coach runs well on a tank the gauge says is 'empty' but
> stumbles and dies in classic 'low fuel condition' on the 'full' tank.
>
> The question: Which input connection is which on the valve?
>
> (Asking just in case the 'empty' tank has a couple of quarts of fuel
> and the 'full' tank fuel pickup tube is clogged or some other scenario
> giving weird results.)
>
> Thanks in advance
>
> Stu
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
>

 

[LQQKatJon]

If you have not replaced it. Replace it now before you are left on side of road stumbling.

Also switch tanks at least once everytime you drive your coach will keep that valve moving and working.

Also best not to run low on fuel to even need the aux 6 gallons. Running low causes issues.

https://www.amazon.com/Standard-Motor-Products-FV1T-Selector/dp/B005ETOVZM/ref=mp_s_a_1_3?dchild=1&keywords=fuel+selector+valve&qid=1622230500&sr=8-3

One port should be marked aux.

2 in’s and 1 out on opposite side.

--
Jon Roche
75 palm beach
EBL EFI, manny headers, Micro Level, rebuilt most of coach now.
St. Cloud, MN
http://lqqkatjon.blogspot.com/

 

[johnny]

The fuel system is a best solution to a nagging problem. There's just at 6" depth in which to mount them. Given a 25 gallon tank 6" deep, you get a
gauge sender with a 6"throw full to empty. Consequently, given the slosh in a moving thin large tank,the gauge is going to be(marginally) accurate
only when the coach is level and has been sitting still for a few minutes. Given the limits generated by the frame members, two tanks are a necessity
to get reasonable range. In order to get a single fill port, the connection to the tanks runs inside the frame and fills each an inch or two above the
bottom. This means they will drain together until you get below the fill port, and then act like separate tanks, each with a bit under ten gallons
in. Ten available when the engine sputters is a reasonable reserve, unless you're traveling in parts of the West. If the vents are properly mounted
(very few are anymore) it's reasonably easy to fill.

--johnny

--
Foolish Carriage, 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

 

[ghickey]

I am just curious what you consider properly mounted vents? 

A year and a half ago I dropped the tanks to work on them and replaced a
couple of cracked hoses (which was causing a bunch of gas to be dumped
on the ground every time I filled up. The good news is that I fixed the
pouring of gas on the ground during fill up, but now there is a back
pressure wave that shoots a stream of gas out of the fill tube shortly
after the gas noozel turns off. I have to try to listen and estimate how
full the tanks are to stop the flow of gas before the pressure wave
pushes the gas up the fill pipe.

When I replaced the vent lines (they were the ones that were cracked)
they went up to the air-liquid separator (or whatever it is) in the rear
driver's side wheel well. I am not sure I understand what would not be
properly mounted as there was not a lot of places I could see could be
changed on the vent lines.

Thanks.

--
Gerard Hickey / WTØF IRLP:3067/Echolink:529661
hickey DMR: 3102272
425-395-4554 Allstar: 531920

> The fuel system is a best solution to a nagging problem. There's just at 6" depth in which to mount them. Given a 25 gallon tank 6" deep, you get a
> gauge sender with a 6"throw full to empty. Consequently, given the slosh in a moving thin large tank,the gauge is going to be(marginally) accurate
> only when the coach is level and has been sitting still for a few minutes. Given the limits generated by the frame members, two tanks are a necessity
> to get reasonable range. In order to get a single fill port, the connection to the tanks runs inside the frame and fills each an inch or two above the
> bottom. This means they will drain together until you get below the fill port, and then act like separate tanks, each with a bit under ten gallons
> in. Ten available when the engine sputters is a reasonable reserve, unless you're traveling in parts of the West. If the vents are properly mounted
> (very few are anymore) it's reasonably easy to fill.
>
> --johnny
>

 

[john r. lebetski]

No power is main (rear) by internal valve spring action. Blow through the valve with a short hose and your mouth . That’s the MAIN. Apply 12V and
the ports switch via solenoid action. Blow through test will show the output port remains same and input switches to Aux (front tank). You can figure
it out this way
--
John Lebetski
Woodstock, IL
77 Eleganza II

 

[johnny]

Properly mounted means no sags or low spots which will alllow liquid to puddle. Matt Colie has anexplanation if I could find it on short notice. The
vent lines are teed and go tpo the fill pipe, Matt uses two lines with the tee up front at the pipe. The separator is in the vapor line which goes to
the vapor cannister up front and is purged to the carb.

--johnny
--
Foolish Carriage, 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