Home » Public Forums » GMCnet » Fuel Gauge/Sender Question
| Fuel Gauge/Sender Question [message #322928] |
Tue, 29 August 2017 10:47  |
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Brian K
Messages: 75
Registered: May 2017
Location: Sherman Oaks, CA
Karma: 0
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Hi everyone. I have a question regarding a fuel problem I've had over my long trip this summer. I've read and searched a lot of the posts too.
Basically, I took a round trip from Seattle to Albuquerque. I ended up having a few hiccups, the worst one was a failed distributor. But at least two times I had to get AAA fuel drops to me, both out of my own stupidity and bravado, but mainly out of readings on my tank.
From all the posts and the literature, and everyone's war stories, I know that the tanks work in principal of drawing from each other and then you switch over at about 1/4 tank (I know this is a gross generalization). The problem I'm having is that either my main tank or my reserve tank will draw to empty, and then the other tank will show over 1/4 to 1/2 full, yet if I'm not careful on monitoring both tanks, I have stalled out and "run out of gas". For example, one time my reserve tank showed empty but the main tank showed between 1/4 and 1/2. Another time it was the opposite. So either my tanks are not drawing correctly or my gauges and senders are off.
I'm trying to combat my stupidity as much as possible by refueling at 200 miles or when at least one tank is under 1/2. But I would like to eventually figure out where to start to solve this problem.
Thanks!!
Brian K
1977 Eleganza II, TZE167V100261
Sherman Oaks, CA
Rebuilt 455, New brake system, a lot of Original Equipment ready to fall apart (discovering more as I go along....)
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| Re: [GMCnet] Fuel Gauge/Sender Question [message #322933 is a reply to message #322928] |
Tue, 29 August 2017 11:07  |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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Brian,
It sounds to me as if you have a failed tank selector valve. Either it's
not switching at all or it's switching half way, allowing air to be
admitted to the line from the empty tank, which prevents the reserve tank
from supplying fuel. Similar problems can arise from leaking hoses.
Unless you know the fuel lines to have been recently replaced with
ethanol-tolerant tubes/hoses, that's the best place to start, and either
include a new selector valve or another solution.
Some disagree, but I consider the best solution to be elimination of the
selector valve and the mechanical (engine-driven) pump. Mount two Carter
4070 electric pumps (with preceding fuel filters) near the fuel tanks,
connecting their outputs through check valves to a single steel line
forward to the front crossmember. Use an oil pressure switch for safety,
driving a power relay followed by a selector relay. Control that selector
relay with the dash Main/Aux tank selector switch. That arrangement
provides vapor lock resistance, pump redundancy, and selector valve
elimination at little more cost than selector valve replacement (~$60x2 for
pumps & filters vs ~$40+ for selector valve).
JMHO,
Ken H.
Americus, GA
'76 X-Birchaven w/Cad500/Howell EFI & EBL,
Manny Brakes & 1-Ton, etc., etc., etc.
www.gmcwipersetc.com
On Tue, Aug 29, 2017 at 11:47 AM, Brian Krikorian wrote:
> Hi everyone. I have a question regarding a fuel problem I've had over my
> long trip this summer. I've read and searched a lot of the posts too.
>
> Basically, I took a round trip from Seattle to Albuquerque. I ended up
> having a few hiccups, the worst one was a failed distributor. But at least
> two times I had to get AAA fuel drops to me, both out of my own stupidity
> and bravado, but mainly out of readings on my tank.
>
> From all the posts and the literature, and everyone's war stories, I know
> that the tanks work in principal of drawing from each other and then you
> switch over at about 1/4 tank (I know this is a gross generalization).
> The problem I'm having is that either my main tank or my reserve tank will
> draw to empty, and then the other tank will show over 1/4 to 1/2 full, yet
> if I'm not careful on monitoring both tanks, I have stalled out and "run
> out of gas". For example, one time my reserve tank showed empty but the
> main tank showed between 1/4 and 1/2. Another time it was the opposite. So
> either my tanks are not drawing correctly or my gauges and senders are off.
>
> I'm trying to combat my stupidity as much as possible by refueling at 200
> miles or when at least one tank is under 1/2. But I would like to
> eventually figure out where to start to solve this problem.
>
> Thanks!!
> --
> Brian K
> 1977 Eleganza II, TZE167V100261
> Bellevue, WA
> Rebuilt 455, New brake system, a lot of Original Equipment ready to fall
> apart (discovering more as I go along....)
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Ken Henderson
Americus, GA
www.gmcwipersetc.com
Large Wiring Diagrams
76 X-Birchaven
76 X-Palm Beach
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| Re: [GMCnet] Fuel Gauge/Sender Question [message #322935 is a reply to message #322933] |
Tue, 29 August 2017 11:15 |
tphipps
Messages: 3005
Registered: August 2004
Location: Spanish Fort, AL
Karma: 9
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Senior Member |
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Do not trust your fuel gauge! Do as Ken suggested. I refuel every 200-250miles and empty my personal tank. Works pretty good.
Tom, MS II
1975 Avion 4 sale
2012 Phoenix Cruiser model 2552
KA4CSG
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| Re: Fuel Gauge/Sender Question [message #322954 is a reply to message #322928] |
Tue, 29 August 2017 15:57 |
jhbridges
Messages: 8412
Registered: May 2011
Location: Braselton ga
Karma: -74
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Senior Member |
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You can also use a pair of Mr Gasket pumps, which have built in check valves. If you use them, do not use the supplied inlet filters, which are known to fail and leak. Replace them with the identical Wix filters. Here's one install:
http://www.gmcmhphotos.com/photos/g6198-cane-9-creek-rv-park-heflin-2c-al.html
That's a piece of 3/32 steel stock cut to fit across the frame anbd crosspiece, with the pumps and relay mounted. The mechanical pump is blocked off and a barbed fitting screwed onto the hard line going to the carb. If you have a mechanical [pump in your spares, you can convert to stock beside the road in maybe 30 minutes. No lines were cut, although some hose was added to the pump outlets.
--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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