Fuel Gauge quit - The 1947 - Present Chevrolet & GMC Truck Message Board Network

garold99 · 04-29-2005, 01:37 PM

About 2 years ago my fuel gauge just quit working. It worked fine till then. Any ideas what might have happened and what it would take to fix it?

71 Chevy longbed
350 auto

garold99 · 04-29-2005, 01:39 PM

Forgot, since gauge quit I've been using mileage to guess when I'm getting low on gas. I fill it up every 200 miles just to make sure I dont run out of gas, which is never any fun.

shifty · 04-29-2005, 01:44 PM

Basically, the gist of what I've gotten from others is this:

Gas gauge is three basic parts:
1) The dash gauge
2) The sending unit (on the tank)
5) The wire connecting the two

The sending unit sends out a 0-90 ohm signal (pretty sure it's ohms) depending on whether it's full or empty. Logically, I would think this would be the way to test:

Take a multimeter to the sending unit where the wire attaches to it. If you get resistance between 0-90 ohms, you know the sending unit is good. If there is not resistance, the sending unit is probably bad.

If the sending unit is good, trace the wire back to the dash and make sure it's not grounded out somewhere. Disconnect (or tap onto) the wire where it meets the dash gauge; Take a multimeter to it and test for resistance. If you have resistance, I would think the gauge is bad.

shifty · 04-29-2005, 01:47 PM

PS - I guess before you test things, you should probably check both ends of the wire to make sure they're connected to the dash gauge and sending unit, then check the wire. This might save you the hassle of whipping out (or buying) a multimeter.

Replacement gauges are only ~$10 at the auto parts stores - you could probably crack one open, test the end of the line, see if you get a reading, then package it up and return it. Just don't cut the wires on it and they probably won't care.

jtminton · 04-29-2005, 02:41 PM

Does it read empty or full all the time?

70c10 · 04-29-2005, 02:58 PM

If it reads low you could have a pin hole in the float. I went thru this already.

1STtimePRo'71 · 04-29-2005, 10:26 PM

What if it reads a little on the minus side of emply and the Ebrake dummy light is always on? LOL..........No seriously! I'm tired of that light

68w/sbc406 · 04-29-2005, 11:50 PM

Quote:

Originally Posted by 1STtimePRo'71

Ebrake dummy light is always on?

its a brake dummy light, not a e brake. that wire plugs into the bottom of the prop. valve. the only time mine has ever came on is when my master cylinder went out, but i was figuring that out loooooong before the light ever came on

garold99 · 05-01-2005, 12:18 AM

Sorry it took so long to reply,

The gauge reads Empty all the time. So if its the float, what do I do to change it out.

Thanks

04-29-2005, 01:37 PM	#1
garold99 Registered User Join Date: Nov 2004 Location: Moore, Oklahoma Posts: 129	Fuel Gauge quit About 2 years ago my fuel gauge just quit working. It worked fine till then. Any ideas what might have happened and what it would take to fix it? 71 Chevy longbed 350 auto

04-29-2005, 01:44 PM	#3
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,376	Basically, the gist of what I've gotten from others is this: Gas gauge is three basic parts: 1) The dash gauge 2) The sending unit (on the tank) 5) The wire connecting the two The sending unit sends out a 0-90 ohm signal (pretty sure it's ohms) depending on whether it's full or empty. Logically, I would think this would be the way to test: Take a multimeter to the sending unit where the wire attaches to it. If you get resistance between 0-90 ohms, you know the sending unit is good. If there is not resistance, the sending unit is probably bad. If the sending unit is good, trace the wire back to the dash and make sure it's not grounded out somewhere. Disconnect (or tap onto) the wire where it meets the dash gauge; Take a multimeter to it and test for resistance. If you have resistance, I would think the gauge is bad. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

04-29-2005, 01:47 PM	#4
shifty Questionable Join Date: Mar 2005 Location: Atlanta Posts: 13,376	PS - I guess before you test things, you should probably check both ends of the wire to make sure they're connected to the dash gauge and sending unit, then check the wire. This might save you the hassle of whipping out (or buying) a multimeter. Replacement gauges are only ~$10 at the auto parts stores - you could probably crack one open, test the end of the line, see if you get a reading, then package it up and return it. Just don't cut the wires on it and they probably won't care. __________________ If I've got anything up for grabs, it'll be here: 7-hole gauge cluster for a 67-72 p/u FREE (link) I can't check the forum daily. If I don't reply to you within 24 hours, drop me a PM! I'm (hopefully) still alive and will reply faster to a PM.

04-29-2005, 02:41 PM	#5
jtminton II Timothy 4:2 Join Date: Mar 2005 Location: Fort Worth Posts: 361	Does it read empty or full all the time? __________________ 72 C-20 2WD LWB Custom Camper Deluxe 350 4 Speed "Project Lazarus" MY TRUE PRIDE AND JOY "Dangit, Bobby, people will see that oil stain and think I'm a drunk."

04-29-2005, 02:58 PM	#6
70c10 67-72 Addict! Join Date: Feb 2002 Location: The TAX State! Posts: 7,857	If it reads low you could have a pin hole in the float. I went thru this already. __________________ Jim 1970 C/10 Fleetside w/Ghost Flames Lowered 4.5" front and 4" rear (Raked) 355/350 Turbo w/shift kit 10" Redneck Performance Verter w/2500 stall Hooker Super Comps part#2808-1 Performer RPM Air-Gap 12 Bolt w/3:73 gears- Eaton Posi Comp Cams XE262 with 1.6 Crane Energizers, Road Demon 625 and Brodix IK 180 heads

04-29-2005, 01:39 PM	#2
garold99 Registered User Join Date: Nov 2004 Location: Moore, Oklahoma Posts: 129	Forgot, since gauge quit I've been using mileage to guess when I'm getting low on gas. I fill it up every 200 miles just to make sure I dont run out of gas, which is never any fun.

04-29-2005, 10:26 PM	#7
1STtimePRo'71 Registered User Join Date: Feb 2005 Location: Lake Crystal, MN Posts: 656	What if it reads a little on the minus side of emply and the Ebrake dummy light is always on? LOL..........No seriously! I'm tired of that light __________________ -Cory 1967 2 Wheel Chevy

05-01-2005, 12:18 AM	#9
garold99 Registered User Join Date: Nov 2004 Location: Moore, Oklahoma Posts: 129	Sorry it took so long to reply, The gauge reads Empty all the time. So if its the float, what do I do to change it out. Thanks



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