Fuel Sending Unit Problems.. - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Jefe · 01-24-2004, 08:48 PM

Hey guys I have a 72 Chevy L/B 350/Auto that I am working on. The fuel gauge was always off....always read empty pretty much, well I pulled the sending unit and sure enought here was a hole in the float. So I bought a new sending unit and installed it and now it reads a little beyond full and there isn't a full tank of gas in it. I grounded it out properly and it still reads full. I took the brown wire off of the sending unit and the needel swept all the way to the right, and I know the wire is still good. I can't get it to read correctly...possibly the gauge? Any suggesttions would be appreciated. Oh yah...I also just grounded the brown wire out just to see what the gauge would do...and it only goes down to about 1/4 of a tank. Thanks!

Douglas K. Berry

Jefe · 01-25-2004, 12:48 AM

ttt

Sweet72 · 01-25-2004, 01:23 AM

Your wire may be either corroded which will cause high resistance or the gas gauge is bad. If you have a multimeter/ohmmeter check the brown wire for continuity from the gauge to sending unit connection. It should be 0 ohms, anything more and the gauge will read higher than the actual fuel in the tank. The sending unit wire runs under the drivers door sill plate and weather strip, just in case you have to repair or replace it.

Jefe · 01-25-2004, 02:24 PM

The wire does look good. but I haven't checked it under the door sill. Thanks!!

01-24-2004, 08:48 PM	#1
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	Fuel Sending Unit Problems.. Hey guys I have a 72 Chevy L/B 350/Auto that I am working on. The fuel gauge was always off....always read empty pretty much, well I pulled the sending unit and sure enought here was a hole in the float. So I bought a new sending unit and installed it and now it reads a little beyond full and there isn't a full tank of gas in it. I grounded it out properly and it still reads full. I took the brown wire off of the sending unit and the needel swept all the way to the right, and I know the wire is still good. I can't get it to read correctly...possibly the gauge? Any suggesttions would be appreciated. Oh yah...I also just grounded the brown wire out just to see what the gauge would do...and it only goes down to about 1/4 of a tank. Thanks! Douglas K. Berry __________________ -1968 Chevy SWB = Frame Off/383/Muncie Car 4 speed -1968 Chevy SWB = numbers matching 307/Truck 4 speed. -1966 Chevy II = 2 door No Post/130,000 Orig miles/230 6cyl/powerglide/Vintage AC -1972 Chevy Nova = 2 door/412 Small Block -1927 Ford Roadster = Homebuilt/widened 8"/350/ Custom Everything.

01-25-2004, 12:48 AM	#2
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	ttt __________________ -1968 Chevy SWB = Frame Off/383/Muncie Car 4 speed -1968 Chevy SWB = numbers matching 307/Truck 4 speed. -1966 Chevy II = 2 door No Post/130,000 Orig miles/230 6cyl/powerglide/Vintage AC -1972 Chevy Nova = 2 door/412 Small Block -1927 Ford Roadster = Homebuilt/widened 8"/350/ Custom Everything.

01-25-2004, 01:23 AM	#3
Sweet72 Registered User Join Date: Nov 2003 Location: Alexandria, VA Posts: 1,534	Your wire may be either corroded which will cause high resistance or the gas gauge is bad. If you have a multimeter/ohmmeter check the brown wire for continuity from the gauge to sending unit connection. It should be 0 ohms, anything more and the gauge will read higher than the actual fuel in the tank. The sending unit wire runs under the drivers door sill plate and weather strip, just in case you have to repair or replace it. __________________ '72 GMC SWB C1500 Custom, frame-off in progress. 383 SBC, 9:1CR, Comp Cams XE262H, Scat internal balanced crank, Eagle SIR 6" rods, Keith Black dish pistons, Dart Iron Eagle 72/180 heads, Weiand Stealth intake, Stewart stage I water pump, Holley 4bbl vac sec, TH350 with B&M Shift Improver Kit. 12 bolt positraction.

01-25-2004, 02:24 PM	#4
Jefe Registered User Join Date: Jul 2000 Location: Chandler, Arizona, USA Posts: 299	The wire does look good. but I haven't checked it under the door sill. Thanks!! __________________ -1968 Chevy SWB = Frame Off/383/Muncie Car 4 speed -1968 Chevy SWB = numbers matching 307/Truck 4 speed. -1966 Chevy II = 2 door No Post/130,000 Orig miles/230 6cyl/powerglide/Vintage AC -1972 Chevy Nova = 2 door/412 Small Block -1927 Ford Roadster = Homebuilt/widened 8"/350/ Custom Everything.



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