bullmecha
Forum Newbie
Posts: 3
Loc: Texas
Reg: 07-25-12
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07-25-12 12:36 PM - Post#2252066
Hey all,
I have been randomly reading forums on fuel gauge issues and have done most of the troubleshooting that was mentioned. I have a problem that I have not read anything on in my '72.
The single sending unit wire is fine to fuse box, remove it goes past full connect goes to empty.
When I removed the Sending unit to check the float, it did not seem to have any holes or sloshing sound of fuel inside. I grounded the unit to the truck,turned on key and moved the float lever, the gauge read just fine. After I reinstalled it failed to move from empty when key was turned on. I then tried to ground the unit to the tank and still got no reading on the gauge with a full tank.
Any advice is welcome.. It's annoying me to no end LOL
1972 Custom Deluxe Long Bed
350 (unknown bore)
700r4 tranny (OD for mileage)
Edelbrock 1406 Carb
Edelbrock Intake |
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LGriffin
Member
Posts: 400
Age: 67
Loc: Gateway to Yosemite
Reg: 04-16-04
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07-25-12 04:58 PM - Post#2252153
In response to bullmecha
Sounds like you've done everything right. The only question I have is where did you ground it when it worked right? Did you ry grounding the tank?
Larry
I don't own a vehicle that isn't old enough to drink.
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 JimKshortstep4x4
Chevytalk Moderator & "9th Year" Silver Supporting Member
Posts: 4161
Loc: Muskegon, MI, USA
Reg: 03-28-02
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07-25-12 05:25 PM - Post#2252165
In response to bullmecha
Check the ohm reading from the sending unit to ground. It should read between 0 ohms to 90 ohms.
0=empty 90=full. I assume that the float is good and not full of gasoline. The brass floats are known to leak.
It sounds like the dash unit is ok but don't rule it out as there is a resistor on the back of the gauge that can cause random readings if it is faulty.
Let us know what you find out.
Jim
Member 65-66 Full Size Chevrolet Club
65 Impala SS, 400sbc, Muncie M-22
66 Impala SS, 396, TH 400
69 El Camino, 350, TH 350
71 Short bed stepside 4x4, 350/350
71 Snow plow, 4x4, 350, TH 350
Current project, 72 GMC Shortbed, stepside, 427 |
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64ss409
Senior Member
Posts: 600
Loc: Montana
Reg: 12-04-02
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07-25-12 06:17 PM - Post#2252184
In response to JimKshortstep4x4
If it read properly when the sender was out of the tank, but won't read when installed back in the tank, it sounds like a full float, like Jim mentioned. Did it feel heavy?
Ron
1964 SS 409/340 4 spd, bought new Oct '63
1964 Biscayne-will have 409
1962 SS convertible 4 spd 327
1971 K10 454
99 Silverado Z11
1998 C5 convertible, torch red black top |
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chassisdude
Forum Newbie
Posts: 4
Reg: 09-05-12
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09-05-12 01:18 PM - Post#2266840
In response to bullmecha
Just seen this post and I have the exact same problem with my 71 C10 fuel sending unit. Bought new unit from LMC, put in tank and thought problem solved Wrong same as posted sending unit in tank stays on empty, but take sending unit out of tank, hold it against tank for ground, move float up and down and gage works like it should. Please help I'm going crazy I cant figure out what to do to fix it. Please either mail me or respond on site if you have a idea.. Thamks again chassisdude ( Rick)
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 WagonMan
"3rd Year" Silver Supporting Member
Posts: 1265
Age: 65
Loc: SW Kansas
Reg: 10-26-04
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09-05-12 04:29 PM - Post#2266890
In response to chassisdude
Have you both confirmed that the tank is grounded? Run a jumper wire from a sending unit mounting screw to the cab sheet metal to make sure.
Charles
57 210 4dr. Wagon(bought '82)
-350/700r4 Mild Custom
56 BA 4dr. ht.(bought '98)
-265/TH350 Mostly Stock
29 Ford Sedan(bought '75)
-4.3L/TH350(in progress)
53 Chevy 3100 (bought '96)
-250 I6/TH350 |
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JimKshortstep4x4
Chevytalk Moderator & "9th Year" Silver Supporting Member
Posts: 4161
Loc: Muskegon, MI, USA
Reg: 03-28-02
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09-05-12 04:43 PM - Post#2266895
In response to chassisdude
Welcome to Chevy Talk from West Michigan!
If you still have a problem after verifying ground as suggested check ohm reading at sending unit. It should read between 0 ohms, empty and 90 ohms full.
Jim
Member 65-66 Full Size Chevrolet Club
65 Impala SS, 400sbc, Muncie M-22
66 Impala SS, 396, TH 400
69 El Camino, 350, TH 350
71 Short bed stepside 4x4, 350/350
71 Snow plow, 4x4, 350, TH 350
Current project, 72 GMC Shortbed, stepside, 427 |
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LGriffin
Member
Posts: 400
Age: 67
Loc: Gateway to Yosemite
Reg: 04-16-04
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09-05-12 05:23 PM - Post#2266911
In response to chassisdude
If the sending unit works good when removed and grounded. Doesn't work when installed, it can only be two things; the float has a leak is filling with gas, or it is loosing it's ground. You can check the float by putting it in a pan of water and slowly heat, if you see air bubbles or gas on the water you have a bad float. The grounding is not so simple. If you have a continuity checker, connect it to the terminal for the gauge, go to any part of the sender and have continuity to any part of the sender. Using a VOM connect to the terminal for the gauge and the top of the sender gas line, or,,,. Then move the arm with the float, the resistance should change as you move the arm.
Larry
I don't own a vehicle that isn't old enough to drink.
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chassisdude
Forum Newbie
Posts: 4
Reg: 09-05-12
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09-06-12 06:32 AM - Post#2267024
In response to LGriffin
Thanks guys, I'm sure I'm missing something simple but the tank has to have good ground because gage works when held against outside of tank. Scuffed all surfaces on tank, sending unit and locking ring to make sure good ground to tank, put sending unit in tank and goes to empty. I believe I read that when key on and wire pulled off sending unit stud the guage should go to past full which it does. What else could it be, I'm thinking that that opld sending unit was still good and there has to be something I'm missing..
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LGriffin
Member
Posts: 400
Age: 67
Loc: Gateway to Yosemite
Reg: 04-16-04
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09-06-12 08:12 AM - Post#2267060
In response to chassisdude
Lets see if we can figure out where the circuit is broken.
What part of the sender are you grounding to the tank when it is out?
Have you run a jumper between the top of the sender and ground when installed?
Larry
I don't own a vehicle that isn't old enough to drink.
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chassisdude
Forum Newbie
Posts: 4
Reg: 09-05-12
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09-06-12 08:39 AM - Post#2267065
In response to LGriffin
Larry thanks for trying to help me. When sending unit is out of tank, I hold it with the outer edge of unit mounting plate or lid up against the side wall of the tank between the seats, gauge works good. I have tried holding wire from the point of ground when unit out of tank to the plate or mounting body of unit, still doesnt work. Am I right in thinking with the wire disconnected at sending unit, gauge reads over full, so circuit not complete, so what does it mean when connected and gauge reads empty ???? So confused.. Can I call you???
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chassisdude
Forum Newbie
Posts: 4
Reg: 09-05-12
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09-10-12 11:35 AM - Post#2268378
In response to chassisdude
 I want to thank Larry and the rest of you guys that responded to my question about fuel sending unit. The float was taken in fuel, a very small hole in soldered end, dried float out and re-soldered seems to work now. Thanks Rick
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JimKshortstep4x4
Chevytalk Moderator & "9th Year" Silver Supporting Member
Posts: 4161
Loc: Muskegon, MI, USA
Reg: 03-28-02
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09-10-12 04:36 PM - Post#2268475
In response to chassisdude
Glad you got it fixed! The floats do get brittle over time so don't be surprised if it leaks again.
Jim
Member 65-66 Full Size Chevrolet Club
65 Impala SS, 400sbc, Muncie M-22
66 Impala SS, 396, TH 400
69 El Camino, 350, TH 350
71 Short bed stepside 4x4, 350/350
71 Snow plow, 4x4, 350, TH 350
Current project, 72 GMC Shortbed, stepside, 427 |
|
LGriffin
Member
Posts: 400
Age: 67
Loc: Gateway to Yosemite
Reg: 04-16-04
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09-10-12 05:55 PM - Post#2268506
In response to chassisdude
Good show for both finding and fixing. Those floats are not the easiest things to solder.
Larry
I don't own a vehicle that isn't old enough to drink.
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