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| FUEL SELECTOR SWITCH-caution [message #317164] |
Sun, 07 May 2017 17:52  |
Michael Bozardt
Messages: 367
Registered: January 2007
Location: College Station, Texas
Karma: 1
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My fuel gauge failed. First the main tank part and later the reserve tank part. I managed by stopping every 125 miles for fuel. For over a year, I could not find the problem. Dropped the tanks, installed new sending units, no change.
For. no apparent reason, I decided to change the fuel selector valve. I had already changed all the fuel filters and fuel pump to no advantage. I bought the part locally and installed it near where the original fuel selector valve is, removing the original part. When I finally managed to get the engine running, I noticed the fuel gauges were working. Since someone had stolen my fuel while it was in storage( only 4-5 drops remained of 20 gallons), I added 15-17 gallons of fresh fuel from different containers. The gauges were reading almost half full?????? Surprise, surprise, the fuel selector valve must have conked out (before the fuel was stolen, I might add. Gauge was not working before I stored it). So, if you have a problem with your fuel gauge, this is one more thing to check, maybe before you pull the tanks, which is not a fun job.
[Updated on: Sun, 07 May 2017 17:56] Report message to a moderator |
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| Re: [GMCnet] FUEL SELECTOR SWITCH-caution [message #317165 is a reply to message #317164] |
Sun, 07 May 2017 18:21  |
Mike Kelley
Messages: 467
Registered: February 2017
Karma: -2
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Senior Member |
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Where is this fuel selector switch that you replaced located?
Sent from my iPhone
> On May 7, 2017, at 5:52 PM, Michael Bozardt wrote:
>
> My fuel gauge failed. First the main tank part and later the reserve tank part. I managed by stopping every 125 miles for fuel. For over a year, I
> could not find the problem. Dropped the tanks, installed new sending units, no change.
> For. no apparent reason, I decided to change the fuel selector valve. I had already changed all the fuel filters and fuel pump to no advantage. I
> bought the part locally and installed it near where the original fuel selector valve is, removing the original part. When I finally managed to get the
> engine running, I noticed the fuel gauges were working. Since someone had stolen my fuel while it was in storage( only 4-5 drops remained of 20
> gallons), I added 15-17 gallons of fresh fuel from different containers. The gauges were reading almost half full?????? Surprise, surprise, the fuel
> selector valve must have conked out (before the fuel was stolen, I might add). So, if you have a problem with your fuel gauge, this is one more thing
> to check, maybe before you pull the tanks, which is not a fun job.
>
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| Re: FUEL SELECTOR SWITCH-caution [message #317169 is a reply to message #317164] |
Sun, 07 May 2017 20:00 |
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RF_Burns
Messages: 2277
Registered: June 2008
Location: S. Ontario, Canada
Karma: 3
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Mike,
From my reading of Michael's post, he replaced the fuel selector valve, not the switch as mentioned in the posting title.
Michael, in the OEM configuration, the fuel selector valve has nothing to do with the gauges. However from my recollection, there is a connector back by the tanks which carry both the fuel gauges and the fuel selector valve wiring through it. It could be that this connector is/was oxidized causing the fuel gauge issues. When you installed the new fuel selector valve, you may have disturbed this connector cause the contacts to move against each other removing some oxide and restoring connection.
To troubleshoot, use the chassis wiring diagram for your year of manufacturs. The gauges will read Full if the gauge circuit is Open and Empty if it is at or near ground. If reading Full, simply ground each gauge wire and the gauge should go to Empty. Trace through to find where your open connection is. If the gauge always reads Empty, then you have a short to ground. Open the connectors at the Fuel selector switch, then at the rear connector to isolate where the ground fault is.
Of course you could have an open or shorted tank sensor but at least you know that was the issue before buying and installing a new sensor. Also remember it would be unusual for both sensors to fail in the same condition at the same time.
The switch and the gauge are common to both tanks, so if both tanks are reading the same condition, I would start with testing the switch (most likely to fail) then test the gauge right at the back of the gauge.
If you don't troubleshoot right down to the exact problem, then whatever caused the issue in the first place is very likely to re-occur. I hate it when something starts working before I trace to the exact cause.
On the other hand, if the fuel selector valve is not OEM, then the gauge sensor may indeed run though the valve. I have one of these selector valves with 6 wires, however I did not wire the gauges through the valve, I just left that OEM.
Just my farmboy mechanic way of looking at it with no formal edgeyoucation in mikanics or enjunearing
Bruce Hislop
ON Canada
77PB, 455 Dick P. rebuilt, DynamicEFI EBL EFI & ESC.
1 ton front end
http://www.gmcmhphotos.com/photos/showphoto.php?photo=29001
My Staff says I never listen to them, or something like that
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| Re: [GMCnet] FUEL SELECTOR SWITCH-caution [message #317171 is a reply to message #317164] |
Sun, 07 May 2017 20:18 |
Ken Henderson
Messages: 8726
Registered: March 2004
Location: Americus, GA
Karma: 9
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Senior Member |
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MIchael,
I'm trying to figure out HOW your fuel was stolen. Did they remove the
drain plugs? If so, have you made sure they're properly replaced and
tightened? Did they disconnect a fuel line(s) to drain it? Again, have
you correctly re-connected them?
OR, did they siphon it out? If so, I want to meet them; they're some kind
of magicians, IMHO!
Ken H.
On Sun, May 7, 2017 at 6:52 PM, Michael Bozardt wrote:
> My fuel gauge failed. First the main tank part and later the reserve tank
> part. I managed by stopping every 125 miles for fuel. For over a year, I
> could not find the problem. Dropped the tanks, installed new sending
> units, no change.
> For. no apparent reason, I decided to change the fuel selector valve. I
> had already changed all the fuel filters and fuel pump to no advantage. I
> bought the part locally and installed it near where the original fuel
> selector valve is, removing the original part. When I finally managed to
> get the
> engine running, I noticed the fuel gauges were working. Since someone had
> stolen my fuel while it was in storage( only 4-5 drops remained of 20
> gallons), I added 15-17 gallons of fresh fuel from different containers.
> The gauges were reading almost half full?????? Surprise, surprise, the fuel
> selector valve must have conked out (before the fuel was stolen, I might
> add). So, if you have a problem with your fuel gauge, this is one more thing
> to check, maybe before you pull the tanks, which is not a fun job.
>
> _______________________________________________
> GMCnet mailing list
> Unsubscribe or Change List Options:
> http://list.gmcnet.org/mailman/listinfo/gmclist_list.gmcnet.org
>
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Unsubscribe or Change List Options:
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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 SELECTOR SWITCH-caution [message #317175 is a reply to message #317171] |
Sun, 07 May 2017 21:30 |
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Matt Colie
Messages: 8547
Registered: March 2007
Location: S.E. Michigan
Karma: 7
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Senior Member |
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Ken Henderson wrote on Sun, 07 May 2017 21:18MIchael,
I'm trying to figure out HOW your fuel was stolen. Did they remove the
drain plugs? If so, have you made sure they're properly replaced and
tightened? Did they disconnect a fuel line(s) to drain it? Again, have
you correctly re-connected them?
OR, did they siphon it out? If so, I want to meet them; they're some kind
of magicians, IMHO!
Ken H.
Ken,
Maybe we Don't want to meet him.....
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
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| Re: [GMCnet] FUEL SELECTOR SWITCH-caution [message #317177 is a reply to message #317165] |
Sun, 07 May 2017 23:10 |
Michael Bozardt
Messages: 367
Registered: January 2007
Location: College Station, Texas
Karma: 1
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Senior Member |
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Location: Driver's side in the frame rail about18-24 inches in front of the first rear wheel
O----------x-OO
X marks the approximate spot for the fuel selector valve.
The fuel filler cap is locked and was not tampered. They removed it through the drain plug on the front tank. Same way I did before I dropped the tanks. When I put it in storage, it was low on fuel so I put 20 gallons in by hand at the storage facility. The front tank drain plug readily comes out but the rear tank plug will not move. Since the tanks are connected we can empty all but a few gallons through the drain plug. It just takes time and lots of containers.I assumed the remainder evaporated to the canister or somewhere as the tanks were very empty.
[Updated on: Sun, 07 May 2017 23:26] Report message to a moderator |
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