Fuel Gauge

Disclaimer: Links on this page pointing to Amazon, eBay and other sites may include affiliate code. If you click them and make a purchase, we may earn a small commission.

Marcos

Full Access Member
Joined
Dec 24, 2018
Posts
66
Reaction score
7
Location
Pecos
First Name
Marcos
Truck Year
1980
Truck Model
Jimmy
Engine Size
350
I have a fuel Gauge on my 1980 Jimmy that doesn't work. Id like to get it working again. Anyone have any insight what I need to check? not sure if I need to drop my tank and check anything in there or if theres any electrical I should be checking under the Jimmy?

thank you
 

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
Is it doing anything, or is completely dead?
 

C10MixMaster

Full Access Member
Joined
Dec 6, 2016
Posts
756
Reaction score
1,420
Location
Kingman AZ
First Name
Ben
Truck Year
1977
Truck Model
C10 BIG10
Engine Size
ZZ4 350
I have a fuel Gauge on my 1980 Jimmy that doesn't work. Id like to get it working again. Anyone have any insight what I need to check? not sure if I need to drop my tank and check anything in there or if theres any electrical I should be checking under the Jimmy?

thank you

No sure on a jimmy but on the pickups there is a wire at the starter. its a weatherproof spade connector. It will be the single wire that runs to the back of the truck. disconnect it. Use an ohm meter to check the ohms on the wire to the tank.

FUEL LEVEL GAUGE PARAMETERS
For Truck Years: 1967 - 1990
The Fuel Gauge Needle Should Point to:
Left Line (Empty) when sender resistance = ~1 Ω
Middle Line (Half) when sender resistance = 44 Ω
Right Line (Full) when sender resistance = 88 Ω

if its not within these parameters you have have a sender problem.

if that looks good, ground the wire that goes to the gauge. turn the key on engine off. It should show empty when grounded and overfull when not connected to anything. if it fails that test you have a gauge problem.

a gauge that always shows empty could have a bad float. a gauge that always reads over full could have a bad wire or ground.
 

Marcos

Full Access Member
Joined
Dec 24, 2018
Posts
66
Reaction score
7
Location
Pecos
First Name
Marcos
Truck Year
1980
Truck Model
Jimmy
Engine Size
350
the needle always sits at the 1/4 tank mark.

C10mixmaster ill give that a try and update you.

Appreciate the info

thank you
 

AuroraGirl

Full Access Member
Joined
Sep 8, 2019
Posts
9,121
Reaction score
6,038
Location
Northern Wisconsin
First Name
Taylor
Truck Year
1978, 1980
Truck Model
K10, K25
Engine Size
400(?), 350
My gauge actually points past full... by quite a bit. Is it possible the needle is "off track" and needs to be pushed over into normal area?
 

Frankenchevy

Proverbs 16:18
Joined
Jan 3, 2018
Posts
5,904
Reaction score
7,249
Location
USA
First Name
Jeremy
Truck Year
Square
Truck Model
CUCV
Engine Size
Small
My gauge actually points past full... by quite a bit. Is it possible the needle is "off track" and needs to be pushed over into normal area?
Where’s it at when the tank is completely empty?

Could be a bent/worn sender, possible wire issue causing increased resistance, or bad gauge.
 

1987 GMC Jimmy

Automobile Hoarder
Joined
Jan 23, 2016
Posts
5,848
Reaction score
2,387
Location
Mississippi
First Name
Jesse
Truck Year
1987
Truck Model
V1500 Jimmy
Engine Size
350
My gauge actually points past full... by quite a bit. Is it possible the needle is "off track" and needs to be pushed over into normal area?

Mine was like that, and the sender was no good. I haven’t had a gauge problem, but if the fuel gauge works, and you move it with your finger, it’ll just run right back to where it was before.
 

thecantaloupeman

Full Access Member
Joined
May 14, 2019
Posts
447
Reaction score
144
Location
US
First Name
Dawson
Truck Year
1978
Truck Model
C20 Silverado Camper Special
Engine Size
350
No sure on a jimmy but on the pickups there is a wire at the starter. its a weatherproof spade connector. It will be the single wire that runs to the back of the truck. disconnect it. Use an ohm meter to check the ohms on the wire to the tank.

FUEL LEVEL GAUGE PARAMETERS
For Truck Years: 1967 - 1990
The Fuel Gauge Needle Should Point to:
Left Line (Empty) when sender resistance = ~1 Ω
Middle Line (Half) when sender resistance = 44 Ω
Right Line (Full) when sender resistance = 88 Ω

if its not within these parameters you have have a sender problem.

if that looks good, ground the wire that goes to the gauge. turn the key on engine off. It should show empty when grounded and overfull when not connected to anything. if it fails that test you have a gauge problem.

a gauge that always shows empty could have a bad float. a gauge that always reads over full could have a bad wire or ground.
Thanks for this. I've been having a similar issue. My tank reads overfull.

Sent from my SM-G950U using Tapatalk
 

eskimomann209

Full Access Member
Joined
Jan 9, 2019
Posts
1,849
Reaction score
1,998
Location
Modesto
First Name
Marcus
Truck Year
1973
Truck Model
C10
Engine Size
5.3
Mine was like that, and the sender was no good. I haven’t had a gauge problem, but if the fuel gauge works, and you move it with your finger, it’ll just run right back to where it was before.
This is correct. But you can pull the needle and re seat it.
Wouldn’t recommend it they’re brittle. Id check grounds ( mainly one inside frame where the tank hangs) and 12v at the gauge and signal. If you have that you should have everything. You can measure resistance at the cluster plug to see about where it should be, I filled mine up and then read it so I knew exactly what it should read.
I finally got al my gauges working after a lot of fussing
 

Dmack

Full Access Member
Joined
Mar 13, 2019
Posts
306
Reaction score
382
Location
Central OR
First Name
Dave
Truck Year
1983
Truck Model
K20
Engine Size
350
If it rests last full, at 3 o'clock, it usually means you have an open circuit. Generally a broken or disconnected wire, or broken sending unit connection, as some mentioned before.
 

C10MixMaster

Full Access Member
Joined
Dec 6, 2016
Posts
756
Reaction score
1,420
Location
Kingman AZ
First Name
Ben
Truck Year
1977
Truck Model
C10 BIG10
Engine Size
ZZ4 350
the needle always sits at the 1/4 tank mark.

C10mixmaster ill give that a try and update you.

Appreciate the info

thank you

sounds like a bad gauge. However check to make sure you have power and ground to the gauge before you replace it.
 

Papa John

Member
Joined
Sep 18, 2019
Posts
32
Reaction score
2
Location
Valdosta, Ga
First Name
John
Truck Year
1982
Truck Model
C10
Engine Size
305
Had same issue on my 82 c10 gauge was working then it stopped right below half mark. Filled it back up today still in same spot.
 

Kim Burke

Full Access Member
Joined
Dec 9, 2017
Posts
646
Reaction score
832
Location
Northern IN
First Name
Kim
Truck Year
1979
Truck Model
C1500
Engine Size
454
First of all, I fought these squarebody fuel tanks for the better part of 6 mos. and still don’t know if mine are “exactly” right. So I’m not the expert but this I do know, ohms = resistance so splices have to been weather proofed or the corrosion will severely effect the accuracy/consistency. Check your connections.
You’re in the right forum, there are some really sharp patient guys on here.
 

C10MixMaster

Full Access Member
Joined
Dec 6, 2016
Posts
756
Reaction score
1,420
Location
Kingman AZ
First Name
Ben
Truck Year
1977
Truck Model
C10 BIG10
Engine Size
ZZ4 350
First of all, I fought these squarebody fuel tanks for the better part of 6 mos. and still don’t know if mine are “exactly” right. So I’m not the expert but this I do know, ohms = resistance so splices have to been weather proofed or the corrosion will severely effect the accuracy/consistency. Check your connections.
You’re in the right forum, there are some really sharp patient guys on here.

Yes add resistance and the gauge will read hi.
 

Papa John

Member
Joined
Sep 18, 2019
Posts
32
Reaction score
2
Location
Valdosta, Ga
First Name
John
Truck Year
1982
Truck Model
C10
Engine Size
305
but what would cause it to work then stop just below half all of sudden. I did wash the body of the truck about 2 weeks ago but other than that no other events or changes ? I ran it bone dry and then filled it up and gauge reads the same ?
 

Forum statistics

Threads
41,851
Posts
903,488
Members
33,365
Latest member
rossivey
Top