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Fuel tank selector switch/solenoid. Really needed? [message #316641] Wed, 26 April 2017 11:08 Go to next message
Scott Nutter is currently offline  Scott Nutter   
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Hello,
I'm getting ready to replace all my original fuel line to the ethanol resistent fuel fine.
I would like to simplify the design and go from the tanks to a coupler, single line outside the frame to a hard mount fuel filter, to a hard mount electric fuel pump with a bypass hose(as close to the tanks as I can get), to a long run to the mechanical engine fuel pump. The fuel selector switch would be used to turn on the electric fuel pump, if needed.
My question is, by eliminating the tank selector switch would this cause any future problems or issues? I am one of those guys who stops for fuel every 200 to 250 miles anyways.
Thanks, Scott.


Scott Nutter 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI Houston, Texas
Re: [GMCnet] Fuel tank selector switch/solenoid. Really needed? [message #316643 is a reply to message #316641] Wed, 26 April 2017 11:20 Go to previous messageGo to next message
Emery Stora is currently offline  Emery Stora   United States
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You could have a problem doing this.
Because fuel can flow from one tank to the other if you allow the gas level to go below the tank fill connection (about 1/2 tank) one tank could go quite low if you are going up or down hills and then your fuel tank could suck air and your engine would die on the road.

You could get around this by installing two electric fuel pumps, one for each tank (either in-tank or external) and connecting them with a relay that would switch from one tank to the other using your dash mounted Main/Aux switch.

Emery Stora
77 Kingsley
Frederick, CO
> On Apr 26, 2017, at 10:08 AM, Scott Nutter wrote:
>
> Hello,
> I'm getting ready to replace all my original fuel line to the ethanol resistent fuel fine.
> I would like to simplify the design and go from the tanks to a coupler, single line outside the frame to a hard mount fuel filter, to a hard mount
> electric fuel pump with a bypass hose(as close to the tanks as I can get), to a long run to the mechanical engine fuel pump. The fuel selector switch
> would be used to turn on the electric fuel pump, if needed.
> My question is, by eliminating the tank selector switch would this cause any future problems or issues? I am one of those guys who stops for fuel
> every 200 to 250 miles anyways.
> Thanks, Scott.
> --
> Scott Nutter
> 1978 455 Royale Center Kitchen, Quad bags.
> Houston, Texas
>
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316647 is a reply to message #316641] Wed, 26 April 2017 12:25 Go to previous messageGo to next message
Scott Nutter is currently offline  Scott Nutter   
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Emery,
If I coupled both fuel tank lines together just outside of the tanks, wouldn't I always have fuel going to either line "a" or "b" to the coupler as long as I have some fuel in each tank? Even if I'm on a hill, one of the fuel lines should feed the main line? Or am I overlooking the obvious?
Thanks.


Scott Nutter 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI Houston, Texas
Re: Fuel tank selector switch/solenoid. Really needed? [message #316648 is a reply to message #316641] Wed, 26 April 2017 12:52 Go to previous messageGo to next message
cbryan   United States
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Location: Ennis, Texas
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Yes, Scott,

I learned the hard way about this issue. My beloved P.O. plumbed both together, so when smugly switching to the aux tank, I was out (in the Mojave Desert. I got to the vicinity of a gas station by weaving back and forth to slosh the fuel up to the intakes. Felt like a NASCAR driver of old. What you are missing is that if one fuel pickup is in the air, the pump will just draw that air so that there is no suction sufficient to draw the fuel back out of the other tank. I fixed that later in the trip for a few miles with a vise grip pinching off one tank feed. That's one reason behind the otherwise mysterious advice often heard and read on the forum not to run the tanks below 1/4 full.

The dual pump solution sounds to be the best under the circumstances and it is really nice to know if a pump goes out suddenly (is there any other way?), you have one you can switch to until you can conveniently get under the coach to replace it. Peace of mind about one thing at least. I wonder just what the best practice is? I was going to mount a relay underneath, but am starting to be convinced by taking the trouble to run power wires to the dash switch and doing without another relay with the attendant possible fire hazard, which I think is minimal. And if the relay's coil goes out, you would still have 12 volts to one pump through the normally closed contacts.

Carey



Carey from Ennis, Texas 78 Royale, 500 Cadillac, Rance Baxter EFI.

[Updated on: Wed, 26 April 2017 13:01]

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Re: [GMCnet] Fuel tank selector switch/solenoid. Really needed? [message #316649 is a reply to message #316647] Wed, 26 April 2017 13:00 Go to previous messageGo to next message
emerystora is currently offline  emerystora   United States
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Yes, one fuel line might feed the main line when on a hill but the other one might feed air. Air bubbles in the line would compress and act just like vapor lock and you won't have fuel pressure at the carb (or throttle body if you have fuel injection.)

You have to pull from only one tank to assure it working properly.

Emery Stora
77 Kingsley
Frederick, CO

> On Apr 26, 2017, at 11:25 AM, Scott Nutter wrote:
>
> Emery,
> If I coupled both fuel tank lines together just outside of the tanks, wouldn't I always have fuel going to either line "a" or "b" to the coupler as
> long as I have some fuel in each tank? Even if I'm on a hill, one of the fuel lines should feed the main line? Or am I overlooking the obvious?
> Thanks.
>
> --
> Scott Nutter
> 1978 455 Royale Center Kitchen, Quad bags.
> Houston, Texas
>
> _______________________________________________
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> Unsubscribe or Change List Options:
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316650 is a reply to message #316648] Wed, 26 April 2017 13:31 Go to previous messageGo to next message
Bullitthead is currently offline  Bullitthead   United States
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Put the relay under the hood, not under the coach. Good wiring will rarely fail, but connections in the weather almost always break down.

Terry Kelpien ASE Master Technician 73 Glacier 260 Smithfield, Va.
Re: Fuel tank selector switch/solenoid. Really needed? [message #316652 is a reply to message #316650] Wed, 26 April 2017 14:38 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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If you are going to remove the selector valve and add a second pump you are probably going to need a pair of check valves to prevent one pump from back feeding through the other one. It seems to me like a lot of effort, and money just to eliminate a selector valve.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: Fuel tank selector switch/solenoid. Really needed? [message #316654 is a reply to message #316641] Wed, 26 April 2017 14:49 Go to previous messageGo to next message
lqqkatjon is currently offline  lqqkatjon   United States
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Just did fuel lines, and never understand why people are afraid of the selector valve. They are $35, and i guess i personally have yet to see a newer one fail in the 6 years i have been around GMC's. Even if it would fail, plumbing around it is quick and pretty painless.

Here is a post of the fuel line replacement I just did. I started on saturday morning, and fuel tanks were back in, and I made a late dinner out. Had some misc stuff to finish up on sunday morning, so the whole job was not too tough.

Here are some photos and how I did the selector valve and added an aux fuel pump. Others go the two fuel pump route, but this has worked well for me going on 6 years now and in my humble opinion,
Much easier and simpler.


http://lqqkatjon.blogspot.com/2017/04/fuel-lines.html?m=1


Jon Roche 75 palm beach EBL EFI, manny headers, Micro Level, rebuilt most of coach now. St. Cloud, MN http://lqqkatjon.blogspot.com/
Re: Fuel tank selector switch/solenoid. Really needed? [message #316656 is a reply to message #316641] Wed, 26 April 2017 15:18 Go to previous messageGo to next message
Scott Nutter is currently offline  Scott Nutter   
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Good points/explanitations. Thanks. I'm going to keep it stock with the selector switch intact. Maybe just run one fuel pump tied into the selector switch "aux" position, and see how that works out. I could always install the 2nd fuel pump later if needed.
And thanks for the help..
Scott


Scott Nutter 1978 Royale Center Kitchen, Patterson 455, switch pitch tranny, 3.21 final drive, Quad bags, Dave Lenzi super duty mid axle disc brakes, tankless water heater, everything Lenzi. Alex Ferrera installed MSD Atomic EFI Houston, Texas
Re: [GMCnet] Fuel tank selector switch/solenoid. Really needed? [message #316659 is a reply to message #316656] Wed, 26 April 2017 15:29 Go to previous messageGo to next message
Billy Massey is currently offline  Billy Massey   United States
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You'll like it, Scott. Best of both worlds.

bdub

On Apr 26, 2017 3:19 PM, "Scott Nutter" wrote:

> Good points/explanitations. Thanks. I'm going to keep it stock with the
> selector switch intact. Maybe just run one fuel pump tied into the selector
> switch "aux" position, and see how that works out. I could always install
> the 2nd fuel pump later if needed.
> And thanks for the help..
> Scott
> --
> Scott Nutter
> 1978 455 Royale Center Kitchen, Quad bags.
> Houston, Texas
>
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>
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bdub
bdub.net
Re: Fuel tank selector switch/solenoid. Really needed? [message #316660 is a reply to message #316641] Wed, 26 April 2017 15:52 Go to previous messageGo to next message
A Hamilto is currently offline  A Hamilto   United States
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In the interest of thread drift, why does the fuel stuff have to be on the driver's side? If the exhaust ran on the driver's side and the fuel plumbing was all on the passenger's side, it would be better to work on stuff with your legs sticking out on the shoulder side instead of the traffic side.
Re: Fuel tank selector switch/solenoid. Really needed? [message #316662 is a reply to message #316641] Wed, 26 April 2017 16:46 Go to previous messageGo to next message
jhbridges is currently offline  jhbridges   United States
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Here's my solution using two Mr. Gasket pumps with built in check valves:

http://www.gmcmhphotos.com/photos/cane-9-creek-rv-park-heflin-2c-al/p58467-fuel-pump-follies.html
- several pictures.

If you do this, replace the supplied filters with the Wix replacements. The originals tend to leak at the joint where they're swaged together.

--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
Re: Fuel tank selector switch/solenoid. Really needed? [message #316680 is a reply to message #316660] Thu, 27 April 2017 07:59 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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A Hamilto wrote on Wed, 26 April 2017 16:52
In the interest of thread drift, why does the fuel stuff have to be on the driver's side? If the exhaust ran on the driver's side and the fuel plumbing was all on the passenger's side, it would be better to work on stuff with your legs sticking out on the shoulder side instead of the traffic side.

This is one of those design issues that you have to wonder about.
This also makes the exhaust on the curb/door side. The OE dump was in the middle, so that could not have been the driver.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: Fuel tank selector switch/solenoid. Really needed? [message #316683 is a reply to message #316680] Thu, 27 April 2017 08:13 Go to previous messageGo to next message
Matt Colie is currently offline  Matt Colie   United States
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There is a fuel system issue here that has been completely neglected here.

The APU/generator/genset fuel pickup is in the main tank and only reaches to the 1/4 mark (more or less).

So:
If you run out the main (rear) tank, making electricity is now not an option.
If the tanks are combined and you are below that 1/4 mark the same condition exists.

Yes, I am a little paranoid. I am old and paranoid.

You may not think this matters that much and if you are a blue roads driver that only stops in campgrounds, it might never be any problem. We don't use the coach that way. We go places that we wanted to go because doing it as a passcar roadtrip was impractical.

Matt


Matt & Mary Colie - Chaumière -'73 Glacier 23 - Members GMCMI, GMCGL, GMCES
Electronically Controlled Quiet Engine Cooling Fan with OE Rear Drum Brakes with Applied Control Arms
SE Michigan - Near DTW - Twixt A2 and Detroit
Re: Fuel tank selector switch/solenoid. Really needed? [message #316754 is a reply to message #316641] Fri, 28 April 2017 18:35 Go to previous messageGo to next message
David del Rio is currently offline  David del Rio   United States
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I'm following with great interest as one of my next projects is to replace the fuel lines. I understand the benefit of keeping the selector valve, but am unclear on the one vs two fuel pump(s) option...

Sincerely,
Dave


David del Rio - 75 Avion - Raymond, CA
Re: [GMCnet] Fuel tank selector switch/solenoid. Really needed? [message #316755 is a reply to message #316754] Fri, 28 April 2017 19:26 Go to previous messageGo to next message
Emery Stora is currently offline  Emery Stora   United States
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If you use two fuel pumps (one to each tank pickup) you can eliminate the selector valve.

And, if you have two fuel pumps you have a backup just in case one goes bad.

Emery Stora
77 Kingsley
Frederick, CO

> On Apr 28, 2017, at 5:35 PM, David Horowitz wrote:
>
> I'm following with great interest as one of my next projects is to replace the fuel lines. I understand the benefit of keeping the selector valve,
> but am unclear on the one vs two fuel pump(s) option...
>
> Sincerely,
> Dave
> --
> David del Rio - 75 Avion - Raymond, CA
>
>
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Re: [GMCnet] Fuel tank selector switch/solenoid. Really needed? [message #316764 is a reply to message #316755] Sat, 29 April 2017 01:06 Go to previous messageGo to next message
Ken Burton is currently offline  Ken Burton   United States
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And people with two electric pumps usually eliminate the mechanical pump mounted on the engine. People with one pump usually install the single electric pump in the rear and use it as a boost pump in case of vapor lock.

Ken Burton - N9KB
76 Palm Beach
Hebron, Indiana
Re: Fuel tank selector switch/solenoid. Really needed? [message #316769 is a reply to message #316641] Sat, 29 April 2017 07:32 Go to previous messageGo to next message
jhbridges is currently offline  jhbridges   United States
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With two electric pumps, you can get a bayonet fitting which threads onto the carb hard line from the mechanical pump and remove and bypass the mechanical pump. If you have keep the mechanical pump and put caps on the selector valve, you can revert to stock beside the highway in 30 minutes or less, should both pumps fail. Never had a problem with mine, but, "belt and suspenders'.

--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
Re: Fuel tank selector switch/solenoid. Really needed? [message #316773 is a reply to message #316641] Sat, 29 April 2017 09:12 Go to previous message
Tony Cook is currently offline  Tony Cook   United States
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Also hasn't some used the tank drain plugs as a place to combine the tanks ? Not sure if that's a good idea being that the coaches are so low one good road Apple could really ruin your day.

Tony Cook 77' Kingsley ' SuperSession 77 ' Torrance Beach,CA
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