Gas gauge reads empty to 1/4 only - The 1947 - Present Chevrolet & GMC Truck Message Board Network

72ArizonaBurb · 12-31-2011, 11:14 AM

Guys,

I read about a 20 posts on gas gauge problems but did not find the answer to my problem. I have installed a new fuel sending unit and when I fill the tank it reads 1/4 full. As I drive it goes down to empty. I found a post where another member had this problem but never found a solution posted. Any help will be greatly appreciated.

Happy New Year to All!

zac · 12-31-2011, 05:02 PM

You've probably heard this multiple times, but these problems almost always turn out to be a ground issue. The only one I've ever successfully fixed was my '79 pickup. It was a while back so I don't remember that much, but I spent a ton of time with a diagram following every wire, ended up fixing something on the back of the gauge having to do with the ground, maybe having to do with the printed circuit as well. Whatever I did involved pulling the instrument panel out. I think the set up is similar on 67-72's. The gauge on my '70 burb is intermittent, I haven't even tried yet. I just fill up every 200 miles and ignore it. I'm probably not the only one. Good luck and happy new year, let us know how it goes.

AzDon · 01-01-2012, 03:02 PM

Using Zac's advice, with the tank full, try running a dedicated ground wire from one of the tank-sender flange screws to the chassis. If it doesnt now show full, try pulling the hot wire off the sender and grounding it directly to your new ground wire. If it now shows full, the sender is no good. Look at the gauge with the wire disconnected: Is it now showing empty rather than 1/4? This is further verification that the wire to the rear and gauge are working, but the sender isnt!

72ArizonaBurb · 01-15-2012, 06:40 PM

I pulled my instrument cluster and ran jumper wires from the connectors to the back of the fuel gauge. I also installed a separate gound wire. Gas gauge would still only read 1/4 tank. I then connected a spare gas gauge I have and it went to 3/4 of a tank. I tested another gas gauge I have it when to 3/4 of a tank. Looks like I had a bad gauge or the small circuit on the back of the gauge was bad. I am glad to have this figured out. I will add a separate ground when I re-install it permanently as suggested by several memebers.

12-31-2011, 11:14 AM	#1
72ArizonaBurb Registered User Join Date: Nov 2010 Location: Clarksville TN Posts: 419	Gas gauge reads empty to 1/4 only Guys, I read about a 20 posts on gas gauge problems but did not find the answer to my problem. I have installed a new fuel sending unit and when I fill the tank it reads 1/4 full. As I drive it goes down to empty. I found a post where another member had this problem but never found a solution posted. Any help will be greatly appreciated. Happy New Year to All!

12-31-2011, 05:02 PM	#2
zac Registered User Join Date: Jul 2008 Location: louisville, ky Posts: 502	Re: Gas gauge reads empty to 1/4 only You've probably heard this multiple times, but these problems almost always turn out to be a ground issue. The only one I've ever successfully fixed was my '79 pickup. It was a while back so I don't remember that much, but I spent a ton of time with a diagram following every wire, ended up fixing something on the back of the gauge having to do with the ground, maybe having to do with the printed circuit as well. Whatever I did involved pulling the instrument panel out. I think the set up is similar on 67-72's. The gauge on my '70 burb is intermittent, I haven't even tried yet. I just fill up every 200 miles and ignore it. I'm probably not the only one. Good luck and happy new year, let us know how it goes.

01-01-2012, 03:02 PM	#3
AzDon Registered User Join Date: Oct 2008 Location: Lake Havasu,AZ Posts: 202	Re: Gas gauge reads empty to 1/4 only Using Zac's advice, with the tank full, try running a dedicated ground wire from one of the tank-sender flange screws to the chassis. If it doesnt now show full, try pulling the hot wire off the sender and grounding it directly to your new ground wire. If it now shows full, the sender is no good. Look at the gauge with the wire disconnected: Is it now showing empty rather than 1/4? This is further verification that the wire to the rear and gauge are working, but the sender isnt! Last edited by AzDon; 01-01-2012 at 03:07 PM.

01-15-2012, 06:40 PM	#4
72ArizonaBurb Registered User Join Date: Nov 2010 Location: Clarksville TN Posts: 419	Re: Gas gauge reads empty to 1/4 only I pulled my instrument cluster and ran jumper wires from the connectors to the back of the fuel gauge. I also installed a separate gound wire. Gas gauge would still only read 1/4 tank. I then connected a spare gas gauge I have and it went to 3/4 of a tank. I tested another gas gauge I have it when to 3/4 of a tank. Looks like I had a bad gauge or the small circuit on the back of the gauge was bad. I am glad to have this figured out. I will add a separate ground when I re-install it permanently as suggested by several memebers.



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