Home » Public Forums » GMCnet » Fuel tank selector switch/solenoid. Really needed?
Fuel tank selector switch/solenoid. Really needed? [message #316641] |
Wed, 26 April 2017 11:08 |
Scott Nutter
Messages: 781 Registered: January 2015 Location: Houston/San Diego
Karma: 4
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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
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Re: [GMCnet] Fuel tank selector switch/solenoid. Really needed? [message #316643 is a reply to message #316641] |
Wed, 26 April 2017 11:20 |
Emery Stora
Messages: 959 Registered: January 2011
Karma: 4
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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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> GMCnet mailing list
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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 |
Scott Nutter
Messages: 781 Registered: January 2015 Location: Houston/San Diego
Karma: 4
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Senior Member |
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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
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316648 is a reply to message #316641] |
Wed, 26 April 2017 12:52 |
cbryan
Messages: 451 Registered: May 2012 Location: Ennis, Texas
Karma: 3
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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] Report message to a moderator
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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 |
emerystora
Messages: 4442 Registered: January 2004
Karma: 13
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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
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316652 is a reply to message #316650] |
Wed, 26 April 2017 14:38 |
Ken Burton
Messages: 10030 Registered: January 2004 Location: Hebron, Indiana
Karma: 10
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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
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316654 is a reply to message #316641] |
Wed, 26 April 2017 14:49 |
lqqkatjon
Messages: 2324 Registered: October 2010 Location: St. Cloud, MN
Karma: 5
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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/
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316656 is a reply to message #316641] |
Wed, 26 April 2017 15:18 |
Scott Nutter
Messages: 781 Registered: January 2015 Location: Houston/San Diego
Karma: 4
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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
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316769 is a reply to message #316641] |
Sat, 29 April 2017 07:32 |
jhbridges
Messages: 8412 Registered: May 2011 Location: Braselton ga
Karma: -74
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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
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Re: Fuel tank selector switch/solenoid. Really needed? [message #316773 is a reply to message #316641] |
Sat, 29 April 2017 09:12 |
Tony Cook
Messages: 121 Registered: August 2014 Location: Torrance CA
Karma: 0
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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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