Still having a problem with this d@mn fuel gauge... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

BIG CTY · 11-21-2006, 08:59 AM

OK, The line from the sending unit to the fuse box may very well be pinched. SO my conventional wisdom told me to take off the wire at the sending unit, put ANOTHER wire on and hook that directly to the fuse box where it plugs in and BINGO, it SHOULD work IF the wire was pinched. But this is MY luck we are talking about, or I'm a dumba$$, so no haps. The ground appears to be fine, but I did notice that there was a rubber grommet thing on the sending unit where the brown wire that attaches. The rubber grommet is all tore up.

So now what? Do I need a new sending unit? The gauge still reads all the way over on full, and I'm REALLY tired of having to remember to put gas in this d@mn thing. I'm surely going to run out one day. On a brighter note, I got my tach installed in less than a 1/2 hour. That was pretty easy. Now I need to install my oil/volt/temp gauges (that had BETTER not be a problem!!!) and get this

fuel gauge fixed. HELP HELP HELP!!!

kwkenuf · 11-21-2006, 12:59 PM

DO NOT attach the wire from the sending unit to the fuse box! The sending unit operates by varying the resistance to ground and sending that directly to the gauge. The other side of the gauge is powered from your instrument circuit.
Also if the isolation washer (grommet) at your sending unit is torn up, you could also be picking up a path directly to ground at that spot. To test if that is the case, disconnect the ground source from the sending unit (attached to the body above the tank) and using a multimeter with the controls set for continuity, touch the tank body with one lead and the sending unit output with the other. If you have continuity, your isolation washer is most likely cracked or smooshed (technical term) allowing the connection to contact the tank circumventing the position of the tank float/sending unit.
Remember, NO DC + power is routed through the sending unit. It functions by providing a variable ground to the gauge.

BIG CTY · 11-21-2006, 01:41 PM

OK, I'm a little confused...the brown wire connects to the fuse panel in a little port called "Gas Gauge EXT." So are you saying that the brown wire should NOT connect to the port in the fuse panel? I'm sorry if I sound totally stupid, but I'm FEELING totally stupid right now. Maybe I have it plugged in the wrong port, I dont know what the he!! I'm doing I guess...

So if the brown wire that is attached to the fuel sending unit is NOT supposed to be connected to the fuse panel, where does it connect?

19GMC63 · 11-21-2006, 05:15 PM

The brown wire going from the sending unit goes to the fuel gauge.

There should be two wires going to the fuel gauge, the sending unit wire, and a power wire.

kwkenuf · 11-21-2006, 05:18 PM

Yup, what he said......... If that wire comes from the sending unit, disconnect it from the fuse box and connect it to the gas gauge. Didn't we discuss this same subject a couple weeks back?
Did you use a mirror to take that pic?

BIG CTY · 11-21-2006, 06:50 PM

Quote:

Originally Posted by kwkenuf

Yup, what he said......... If that wire comes from the sending unit, disconnect it from the fuse box and connect it to the gas gauge. Didn't we discuss this same subject a couple weeks back?
Did you use a mirror to take that pic?

Yes, we did discuss it a couple weeks back - but I'm just getting around to fooling with it AND I was/am still stumped. It is not my intent to agitate anyone. Again, my apologies for the confusion. Honestly the wires running to the gauge itself totally escaped me, even though it has been said several times. I guess I was overly focused on the brown wire, sending unit, and fuse panel. I'll see if I can figure it out after this monsoon ends in a couple days.

I took the pic with my phone on the camera, I don't know why it came out like that.

Well, hopefully I can get the 3 gauge cluster installed without much trepidation. I'll search around and see if I can get any pointers before I start asking 1,000,001 questions again!

kwkenuf · 11-21-2006, 11:41 PM

No agitation here......, this is exactly what the board is for, to seek and receive info. Certainly if you have any other questions, fire away.......

BIG CTY · 11-22-2006, 08:31 PM

I give up. The d@mn bolt that holds the brown wire on to the fuel sending unit appears to have fallen in the tank. The rubber fell off and is now on the rusty floor somehwere, so I'm screwed. I am not a stupid person, but for some reason I just cant get this right. Feel free to tell me WTF I should do now. Happy Thanksgiving to you!

624whldr · 11-23-2006, 02:09 PM

sorry to disagree with most on the board but the brown wire from the sending unit i do believe is correct by going to the fuse box. if the gas gage it self is good though take that wire off the tank and while looking the gage momenterally ground it, the gage should go all the way to empty if i remember right. my 62 is this way. look at the wire i believe it has a molded lip that prevent it from being installed in the wrong place.

BIG CTY · 11-23-2006, 04:05 PM

Quote:

Originally Posted by 624whldr

sorry to disagree with most on the board but the brown wire from the sending unit i do believe is correct by going to the fuse box. if the gas gage it self is good though take that wire off the tank and while looking the gage momenterally ground it, the gage should go all the way to empty if i remember right. my 62 is this way. look at the wire i believe it has a molded lip that prevent it from being installed in the wrong place.

This is correct. The brown wire in my truck is going from the sending unit to the fuse panel. If I touch a ground to the bolt (that is now INSIDE the tank I ASSume) it goes down below "E." It's not like this thing never worked, it just stopped after I put my seat in. I have done all I know how and have just screwed it up even more.

49studebaker · 11-24-2006, 12:22 PM

The brown wire I believe does come out of the fuse panel but it's coming from the connection on your instrument panel that varies the resistance. I'm not completely sure but the other folks on this board that said don't use it were just making sure you don't hook up 12 volts directly to the sending unit. That is not a good thing.

BIG CTY · 11-24-2006, 06:34 PM

I'm going to pull the seat back out tomorrow. Thay way it'll be easier to see what the problem is I HOPE. If this doesnt work, I'll be grabbing my 12 gauge and using the bucket for target practice.

pheengurs · 12-30-2006, 03:11 PM

did you ever get this resolved?
I COMPLETELY UNDERSTAND your frustrations with the wiring in these old pickups! If you search back on my few posts, you'll see I've had to do quite a bit of wiring...

anyway, in short, I've custom fab'd a dash panel with all new gauges, and all new wiring for those gauges. But before I did that, I got help from this board on the fuel gauge, amongst other things...

now for your situation, it sounds like you'll need to do the following:
-take new seat out
-take fuel sending unit out (carefully!) and inspect it. if it's missing nuts/bolts, get a really good and flexible magnet grabber, and a breathing mask, and find that nut/bolt ..
-run a new wire from the fusebox to the fuel sending unit on tank.
-run a new wire that grounds on the fuel sending unit, to a GOOD ground

now that last point there is THE MOST IMPORTANT, I found, because all my troubles, kept returning to that. On my truck, I have rust all over the place. I have had to completely redo, and relocate, and create new common ground wires, for the motor, headlights, tailights, gauges and accessories... You'd be surprised how many wierd and odd problems can be associated to bad grounds...

also in my case, I found damage and meltdowns inside the fusebox, so until I can install one of those fancy painless wiring kits, I've had to add a small secondary fuse panel, to take over the duties of the burnt out ports on the original fuse panel, so that is something you may want to check out too...

BIG CTY · 01-02-2007, 01:21 AM

Yep, just Saturday I finally installed my brand new fuel sending unit. Of course with EVERYTHING I do to that d@mn truck something else happens. The install was fine UNTIL I went to put the last bolt on the sending unit. Somehow it got stripped. Well, my overly smart a$$ decided to go fill my truck up to make sure the gauge was working ok....you see where I'm going with this?

Of course it was one of the bottom bolts and gas was seeping out at a rapid pace. I was coming from the botteon o the sending unit (I'm ASSuming becasue it wasnt bolted tightly) and from the the hole that the stripped nut was in. I decided to just drive around for an hour to get the gas down below the sending unit. So I guess I'll either figure out how to "fix" this (and undoubtedly screw something else up), or I'll just make sure not to put any more than 10 gallons in the tank.

At least the gas gauge is working flawlessly...

11-21-2006, 08:59 AM	#1
BIG CTY Between the earth and the sky Join Date: Oct 2006 Location: Chesapeake, VA Posts: 822	Still having a problem with this d@mn fuel gauge... OK, The line from the sending unit to the fuse box may very well be pinched. SO my conventional wisdom told me to take off the wire at the sending unit, put ANOTHER wire on and hook that directly to the fuse box where it plugs in and BINGO, it SHOULD work IF the wire was pinched. But this is MY luck we are talking about, or I'm a dumba$$, so no haps. The ground appears to be fine, but I did notice that there was a rubber grommet thing on the sending unit where the brown wire that attaches. The rubber grommet is all tore up. So now what? Do I need a new sending unit? The gauge still reads all the way over on full, and I'm REALLY tired of having to remember to put gas in this d@mn thing. I'm surely going to run out one day. On a brighter note, I got my tach installed in less than a 1/2 hour. That was pretty easy. Now I need to install my oil/volt/temp gauges (that had BETTER not be a problem!!!) and get this fuel gauge fixed. HELP HELP HELP!!! __________________ Chris - 1966 C10 Shortbed Fleetside, 1991 GMC Sierra 1500 Extended Cab, 1993 Blazer Sport 4x4 My other rides: 1969 Chevrolet Impala SS427 Convertible 1976 Dodge Tradesman B200 2002 Nissan Maxima 6 speed 2004 Mercedes Benz CL500 Last edited by BIG CTY; 11-21-2006 at 09:40 AM.

11-21-2006, 12:59 PM	#2
kwkenuf Retrofit Management Join Date: Apr 2006 Location: Las Vegas, NV Posts: 73	Re: Still having a problem with this d@mn fuel gauge... DO NOT attach the wire from the sending unit to the fuse box! The sending unit operates by varying the resistance to ground and sending that directly to the gauge. The other side of the gauge is powered from your instrument circuit. Also if the isolation washer (grommet) at your sending unit is torn up, you could also be picking up a path directly to ground at that spot. To test if that is the case, disconnect the ground source from the sending unit (attached to the body above the tank) and using a multimeter with the controls set for continuity, touch the tank body with one lead and the sending unit output with the other. If you have continuity, your isolation washer is most likely cracked or smooshed (technical term) allowing the connection to contact the tank circumventing the position of the tank float/sending unit. Remember, NO DC + power is routed through the sending unit. It functions by providing a variable ground to the gauge. __________________ My retrofit fleet -1966 Suburban 2002 Tahoe drivetrain, firewall, floor, chassis and interior in progress -1965 C-10 shortbed stepside, 2003 5.3/4L60E conversion. Power steering, tilt wheel, power front disc brakes, 2.5/4 inch drop, relocated fuel tank and battery, 2002 Silverado buckets and console. Swap Pics -1968 Camaro 95 LT1/4L60E lots o' mods Web Page -1961 Corvette project Corvette Corrections frame, C-4 suspension and brakes, 02 LS1/T-56, Never ending body workPics Last edited by kwkenuf; 11-21-2006 at 01:00 PM.

11-21-2006, 01:41 PM	#3
BIG CTY Between the earth and the sky Join Date: Oct 2006 Location: Chesapeake, VA Posts: 822	Re: Still having a problem with this d@mn fuel gauge... OK, I'm a little confused...the brown wire connects to the fuse panel in a little port called "Gas Gauge EXT." So are you saying that the brown wire should NOT connect to the port in the fuse panel? I'm sorry if I sound totally stupid, but I'm FEELING totally stupid right now. Maybe I have it plugged in the wrong port, I dont know what the he!! I'm doing I guess... So if the brown wire that is attached to the fuel sending unit is NOT supposed to be connected to the fuse panel, where does it connect? __________________ Chris - 1966 C10 Shortbed Fleetside, 1991 GMC Sierra 1500 Extended Cab, 1993 Blazer Sport 4x4 My other rides: 1969 Chevrolet Impala SS427 Convertible 1976 Dodge Tradesman B200 2002 Nissan Maxima 6 speed 2004 Mercedes Benz CL500

11-21-2006, 05:15 PM	#4
19GMC63 Registered User Join Date: Nov 2006 Location: Nashville, TN Posts: 1,510	Re: Still having a problem with this d@mn fuel gauge... The brown wire going from the sending unit goes to the fuel gauge. There should be two wires going to the fuel gauge, the sending unit wire, and a power wire.

11-21-2006, 05:18 PM	#5
kwkenuf Retrofit Management Join Date: Apr 2006 Location: Las Vegas, NV Posts: 73	Re: Still having a problem with this d@mn fuel gauge... Yup, what he said......... If that wire comes from the sending unit, disconnect it from the fuse box and connect it to the gas gauge. Didn't we discuss this same subject a couple weeks back? Did you use a mirror to take that pic? __________________ My retrofit fleet -1966 Suburban 2002 Tahoe drivetrain, firewall, floor, chassis and interior in progress -1965 C-10 shortbed stepside, 2003 5.3/4L60E conversion. Power steering, tilt wheel, power front disc brakes, 2.5/4 inch drop, relocated fuel tank and battery, 2002 Silverado buckets and console. Swap Pics -1968 Camaro 95 LT1/4L60E lots o' mods Web Page -1961 Corvette project Corvette Corrections frame, C-4 suspension and brakes, 02 LS1/T-56, Never ending body workPics Last edited by kwkenuf; 11-21-2006 at 05:22 PM.

11-21-2006, 11:41 PM	#7
kwkenuf Retrofit Management Join Date: Apr 2006 Location: Las Vegas, NV Posts: 73	Re: Still having a problem with this d@mn fuel gauge... No agitation here......, this is exactly what the board is for, to seek and receive info. Certainly if you have any other questions, fire away....... __________________ My retrofit fleet -1966 Suburban 2002 Tahoe drivetrain, firewall, floor, chassis and interior in progress -1965 C-10 shortbed stepside, 2003 5.3/4L60E conversion. Power steering, tilt wheel, power front disc brakes, 2.5/4 inch drop, relocated fuel tank and battery, 2002 Silverado buckets and console. Swap Pics -1968 Camaro 95 LT1/4L60E lots o' mods Web Page -1961 Corvette project Corvette Corrections frame, C-4 suspension and brakes, 02 LS1/T-56, Never ending body workPics Last edited by kwkenuf; 11-21-2006 at 11:41 PM.

11-22-2006, 08:31 PM	#8
BIG CTY Between the earth and the sky Join Date: Oct 2006 Location: Chesapeake, VA Posts: 822	Re: Still having a problem with this d@mn fuel gauge... I give up. The d@mn bolt that holds the brown wire on to the fuel sending unit appears to have fallen in the tank. The rubber fell off and is now on the rusty floor somehwere, so I'm screwed. I am not a stupid person, but for some reason I just cant get this right. Feel free to tell me WTF I should do now. Happy Thanksgiving to you! __________________ Chris - 1966 C10 Shortbed Fleetside, 1991 GMC Sierra 1500 Extended Cab, 1993 Blazer Sport 4x4 My other rides: 1969 Chevrolet Impala SS427 Convertible 1976 Dodge Tradesman B200 2002 Nissan Maxima 6 speed 2004 Mercedes Benz CL500

11-23-2006, 02:09 PM	#9
624whldr drive it not trailer it Join Date: Feb 2005 Location: So Jersey Posts: 64	Re: Still having a problem with this d@mn fuel gauge... sorry to disagree with most on the board but the brown wire from the sending unit i do believe is correct by going to the fuse box. if the gas gage it self is good though take that wire off the tank and while looking the gage momenterally ground it, the gage should go all the way to empty if i remember right. my 62 is this way. look at the wire i believe it has a molded lip that prevent it from being installed in the wrong place.

11-24-2006, 12:22 PM	#11
49studebaker Senior Member Join Date: Nov 2005 Location: Victor, Montana Posts: 386	Re: Still having a problem with this d@mn fuel gauge... The brown wire I believe does come out of the fuse panel but it's coming from the connection on your instrument panel that varies the resistance. I'm not completely sure but the other folks on this board that said don't use it were just making sure you don't hook up 12 volts directly to the sending unit. That is not a good thing. __________________ 04 4x4 GMC Ext. Cab lifted 71 2wd GMC / Ramjet 350 ready for sheet metal 49 Studebaker pickup

11-24-2006, 06:34 PM	#12
BIG CTY Between the earth and the sky Join Date: Oct 2006 Location: Chesapeake, VA Posts: 822	Re: Still having a problem with this d@mn fuel gauge... I'm going to pull the seat back out tomorrow. Thay way it'll be easier to see what the problem is I HOPE. If this doesnt work, I'll be grabbing my 12 gauge and using the bucket for target practice. __________________ Chris - 1966 C10 Shortbed Fleetside, 1991 GMC Sierra 1500 Extended Cab, 1993 Blazer Sport 4x4 My other rides: 1969 Chevrolet Impala SS427 Convertible 1976 Dodge Tradesman B200 2002 Nissan Maxima 6 speed 2004 Mercedes Benz CL500

12-30-2006, 03:11 PM	#13
pheengurs Registered User Join Date: Jul 2006 Location: Calgary, Alberta, Canada Posts: 134	Re: Still having a problem with this d@mn fuel gauge... did you ever get this resolved? I COMPLETELY UNDERSTAND your frustrations with the wiring in these old pickups! If you search back on my few posts, you'll see I've had to do quite a bit of wiring... anyway, in short, I've custom fab'd a dash panel with all new gauges, and all new wiring for those gauges. But before I did that, I got help from this board on the fuel gauge, amongst other things... now for your situation, it sounds like you'll need to do the following: -take new seat out -take fuel sending unit out (carefully!) and inspect it. if it's missing nuts/bolts, get a really good and flexible magnet grabber, and a breathing mask, and find that nut/bolt .. -run a new wire from the fusebox to the fuel sending unit on tank. -run a new wire that grounds on the fuel sending unit, to a GOOD ground now that last point there is THE MOST IMPORTANT, I found, because all my troubles, kept returning to that. On my truck, I have rust all over the place. I have had to completely redo, and relocate, and create new common ground wires, for the motor, headlights, tailights, gauges and accessories... You'd be surprised how many wierd and odd problems can be associated to bad grounds... also in my case, I found damage and meltdowns inside the fusebox, so until I can install one of those fancy painless wiring kits, I've had to add a small secondary fuse panel, to take over the duties of the burnt out ports on the original fuse panel, so that is something you may want to check out too... __________________ 1964 K10 shortbox Stepside 383 sbc stroker under vortec heads sm420 trans / t221 tcase / corp 10 front axle / corp 12 rear axle / 3.73 gears rolling on 33x12x15 tires on 6 lug rims. Last edited by pheengurs; 12-30-2006 at 03:14 PM.

01-02-2007, 01:21 AM	#14
BIG CTY Between the earth and the sky Join Date: Oct 2006 Location: Chesapeake, VA Posts: 822	Re: Still having a problem with this d@mn fuel gauge... Yep, just Saturday I finally installed my brand new fuel sending unit. Of course with EVERYTHING I do to that d@mn truck something else happens. The install was fine UNTIL I went to put the last bolt on the sending unit. Somehow it got stripped. Well, my overly smart a$$ decided to go fill my truck up to make sure the gauge was working ok....you see where I'm going with this? Of course it was one of the bottom bolts and gas was seeping out at a rapid pace. I was coming from the botteon o the sending unit (I'm ASSuming becasue it wasnt bolted tightly) and from the the hole that the stripped nut was in. I decided to just drive around for an hour to get the gas down below the sending unit. So I guess I'll either figure out how to "fix" this (and undoubtedly screw something else up), or I'll just make sure not to put any more than 10 gallons in the tank. At least the gas gauge is working flawlessly... __________________ Chris - 1966 C10 Shortbed Fleetside, 1991 GMC Sierra 1500 Extended Cab, 1993 Blazer Sport 4x4 My other rides: 1969 Chevrolet Impala SS427 Convertible 1976 Dodge Tradesman B200 2002 Nissan Maxima 6 speed 2004 Mercedes Benz CL500 Last edited by BIG CTY; 01-02-2007 at 01:23 AM.



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