need help with gas guage, not what you may think... - The 1947 - Present Chevrolet & GMC Truck Message Board Network

mustanglx347 · 06-06-2004, 12:32 AM

I bought an '82 Blazer which had been converted from a diesel to a small block. The wiring is pretty butchered. My gas gauge sits on full with the key off, then when the key is turned on, the gauge goes past full into the 3 0'clock position. Well, I did some wire tracing, and found the wires from the sending unit have been cut near the firewall. There is a yellow and orange I think. The black is grounded. I am assuming one wire sends power to the sending unit and the other sends the signal to the gauge (I could be worng). Does anyone know which is which? Also, I need to know which wire on the back of the gauge cluster goes to the fuel gauge.

Oh, BTW, the same thing happens with my oil sending unit. The sending unit has the wire plugged into it on the top, but the gauge pegs out when the key is turned on.

Someone please help...It will be greatly appreciated.

Ben

chevythunder · 06-07-2004, 09:47 PM

i know that there is three wires. one from the sending unit, ground, and a hot wire. i know i mixed up the hot wire, and the sending unit wire and had the gauge reading at the 3o'clock position. check the hook ups. could be backwards. just some info

oh and one more helpfull hint. i know that the sending unit wire has a diffrent voltage than the powerwire. if u had atleast 3/4 tank, it would help out even more. power wire has more voltage than the sending wire. (of coarse mine could be diff.) (if u got a voltmeter)

mustanglx347 · 06-08-2004, 10:00 AM

Thanks for the reply. I have a volt meter, but, the wires from the tank are cut back on the frame under the cab. My problem is, I can't find which wires they correspond to on the inside of the firewall. The ground is still hooked up at the tank. Does anyone have a schematic or know where I could get one so I could trace these out??? i am aobut to rip the whole Blazer apart just to fix the gas gauge.

79BIG10 · 06-08-2004, 12:45 PM

Not sure if it would work but the one I have is for a 73-80? model schematic. If you think it would let me know your email and I'll send it to you.

06-06-2004, 12:32 AM	#1
mustanglx347 Registered User Join Date: May 2004 Location: Texas Posts: 44	need help with gas guage, not what you may think... I bought an '82 Blazer which had been converted from a diesel to a small block. The wiring is pretty butchered. My gas gauge sits on full with the key off, then when the key is turned on, the gauge goes past full into the 3 0'clock position. Well, I did some wire tracing, and found the wires from the sending unit have been cut near the firewall. There is a yellow and orange I think. The black is grounded. I am assuming one wire sends power to the sending unit and the other sends the signal to the gauge (I could be worng). Does anyone know which is which? Also, I need to know which wire on the back of the gauge cluster goes to the fuel gauge. Oh, BTW, the same thing happens with my oil sending unit. The sending unit has the wire plugged into it on the top, but the gauge pegs out when the key is turned on. Someone please help...It will be greatly appreciated. Ben __________________ '71 Chevy stepside '50 Chevy 5 window '82 K5 Blazer '90 Mustang-stroked and sprayed '95 Nissan 300 ZX '04 Jeep Grand Cherokee

06-07-2004, 09:47 PM	#2
chevythunder Registered User Join Date: May 2004 Location: chesapeake va. Posts: 29	i know that there is three wires. one from the sending unit, ground, and a hot wire. i know i mixed up the hot wire, and the sending unit wire and had the gauge reading at the 3o'clock position. check the hook ups. could be backwards. just some info oh and one more helpfull hint. i know that the sending unit wire has a diffrent voltage than the powerwire. if u had atleast 3/4 tank, it would help out even more. power wire has more voltage than the sending wire. (of coarse mine could be diff.) (if u got a voltmeter) Last edited by chevythunder; 06-07-2004 at 09:51 PM.

06-08-2004, 10:00 AM	#3
mustanglx347 Registered User Join Date: May 2004 Location: Texas Posts: 44	Thanks for the reply. I have a volt meter, but, the wires from the tank are cut back on the frame under the cab. My problem is, I can't find which wires they correspond to on the inside of the firewall. The ground is still hooked up at the tank. Does anyone have a schematic or know where I could get one so I could trace these out??? i am aobut to rip the whole Blazer apart just to fix the gas gauge. __________________ '71 Chevy stepside '50 Chevy 5 window '82 K5 Blazer '90 Mustang-stroked and sprayed '95 Nissan 300 ZX '04 Jeep Grand Cherokee

06-08-2004, 12:45 PM	#4
79BIG10 I'm back with 2nd truck! Join Date: Feb 2002 Location: Texas Posts: 3,775	Not sure if it would work but the one I have is for a 73-80? model schematic. If you think it would let me know your email and I'll send it to you. __________________ 1979 Chevrolet Bonanza Big10 "Tootsie Roll" 1985 Chevrolet Silverado (wife's) Member of the Southern Bowties Club "Don't underestimate how sexy a fat man who drinks to excess can be." Homer Simpson

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