Checking Fuel gauge - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Red68 · 07-31-2004, 03:48 PM

Does anyone know how to check to see if an original fuel gauge is working properly? I recently installed a new tank under the bed and the fuel gauge does not work. It somewhat worked when it was behind the seat.

JimKshortstep4x4 · 08-01-2004, 07:24 AM

A quick check would be to unplug the brown wire from the tank at the fuse panel. With the wire unplugged and the key on, the dash unit should read well past full. If you ground the terminal, the dash gauge should go to empty.

The tank unit sends out a signal to the dash unit between 0 ohms and 90 ohms. If you check the resistance with an ohm meter (reading between the disconnected brown wire and a good ground) the reading should be between 0 and 90 ohms. If not the problem is in the wiring, tank not grounded, or the sending unit is bad.

Good luck,

Jim

dennis111 · 08-01-2004, 07:57 AM

As mentioned above, you can test your gauge and wiring by alternately shorting and unshorting the brown wire.

You should check to see if the float is saturated or in a bind when it was inserted in the tank.

Removing the assembly and retesting outside of the tank would be advised. (Be sure to apply ground to the mounting disk when testing.)

Dennis

Red68 · 08-01-2004, 08:41 AM

Thanks, guys I will try that.

07-31-2004, 03:48 PM	#1
Red68 Registered User Join Date: Jan 2002 Location: Rhome, TX Posts: 209	Checking Fuel gauge Does anyone know how to check to see if an original fuel gauge is working properly? I recently installed a new tank under the bed and the fuel gauge does not work. It somewhat worked when it was behind the seat. __________________ 1968 C10 LWB 327 bored 40 over, RHS heads, KB pistons, Eagle rods, Edlebrock carb & intake 1968 C10 flatbed 307 w/ 4 spd manual (dads old ride) 1936 1/2 tn pickup, 400sb 350 turbo (partially restored) 1949 1/2 tn, needs complete restore (future project) 1969 Chevy impala 4 dr no post (wifes future car) 2010 GMC Serria 4x4 crew, leveling kit

08-01-2004, 07:57 AM	#3
dennis111 Registered User Join Date: Jul 2004 Location: Amish Wonderland of Central PA. Posts: 31	As mentioned above, you can test your gauge and wiring by alternately shorting and unshorting the brown wire. You should check to see if the float is saturated or in a bind when it was inserted in the tank. Removing the assembly and retesting outside of the tank would be advised. (Be sure to apply ground to the mounting disk when testing.) Dennis __________________ Dennis 68 GMC SWB Custom 1/2 ton, 2WD, 350 V8, PS, PB, 3-Speed, 3:08 12 bolt rear, tilt, tach, vac, cruise and more. . . .

08-01-2004, 08:41 AM	#4
Red68 Registered User Join Date: Jan 2002 Location: Rhome, TX Posts: 209	Thanks, guys I will try that. __________________ 1968 C10 LWB 327 bored 40 over, RHS heads, KB pistons, Eagle rods, Edlebrock carb & intake 1968 C10 flatbed 307 w/ 4 spd manual (dads old ride) 1936 1/2 tn pickup, 400sb 350 turbo (partially restored) 1949 1/2 tn, needs complete restore (future project) 1969 Chevy impala 4 dr no post (wifes future car) 2010 GMC Serria 4x4 crew, leveling kit

08-01-2004, 07:24 AM	#2
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	A quick check would be to unplug the brown wire from the tank at the fuse panel. With the wire unplugged and the key on, the dash unit should read well past full. If you ground the terminal, the dash gauge should go to empty. The tank unit sends out a signal to the dash unit between 0 ohms and 90 ohms. If you check the resistance with an ohm meter (reading between the disconnected brown wire and a good ground) the reading should be between 0 and 90 ohms. If not the problem is in the wiring, tank not grounded, or the sending unit is bad. Good luck, Jim



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