fuel gauge issues

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SLICKCOLLECTOR
Posts: 206
Joined: January 26, 2007, 8:04 pm
Location: eudora ks
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fuel gauge issues

Post by SLICKCOLLECTOR »

after sorting thru the wiring issues and locating a keyed power source i got my ivr working and all power wires to oil pressure and water temperature sensors are pulsating and look to work fine. my orange wire for fuel tank sending unit has the same pulsating current at it should. my fuel tank is the mustang tank installed between the frame rails in the rear. i pulled a new wire to the tank and installed a new sending unit. it pegs the gauge so i ordered a new sending unit. i tested it prior to installing it and the gauge would come up to 1/4 tank. i tested 3 different sending units and all 3 would give me 1/4 tank by operating the float by hand. i installed new sending unit in the tank and connected the wiring and immediately turning the key on the fuel gauge pegs the needle. does that mean that the sending unit is grounding out? the behind the seat factory sending units have a cork gasket between the sending unit and the tank and a ground strap to the sending unit. the mustang tank has a rubber o ring between the sending unit and the tank but has a metal lock ring that grounds the tank and sending unit grounds out the gauge and pegs the needle. i can;t see as to how adding fuel to the tank is going to prevent this sending unit from grounding out. any thought as to how to prevent this grounding? does any of this make sense. the quality of the sending units is not good and i thought initially that was the problem. but no such luck. i have been able to install 4 other tanks in the same manner and get the gauge to work. thanks.

jim
1966 F100 SW 428CJ C6
1965 F100 SW 428 TL sold
1966 F100 SW CVC 428CJ C6
1965 F100 SW CVC 428CJ C6
1966 F100 LB RANGER 390 C6 sold finally
1965 F100 SW CVC 460PI C6
1965 F100 SW CVC 428CJ C6
1972 F100 RANGER XLT SW 428 C6 SOLD
1967 F100 SW CVC 521 C6
1967 F350 390 4 SPEED
1970 F350 428 4 SPEED
1974 F350 428 4 SPEED
1966 F100 523 STROKER C6 GEARVENDORS OVERDRIVE finished
MNTBUGGY
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Joined: July 17, 2016, 7:55 am
Location: Andale, ks
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Re: fuel gauge issues

Post by MNTBUGGY »

Not sure if the helps but had a similar problem with my old jeep. The tank sits against the body and was not getting a good ground the gauge would show a reading but it was not right . I bought a new sending unit and it read the same. I had to run a separate wire to the tank to ground it to the body and a jumper (ground) wire from the frame to the body.

Mike
Mike
1966 F100 4x4 SWB
1966 F100 4x4 LWB
1961 F100 Unibody ( Son's)
1969 Chevelle SS-396
1966 Jeep CJ5
1966 Mustang coupe (wife's )
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FarmMotorSports
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Re: fuel gauge issues

Post by FarmMotorSports »

Sender ohms reading should be between 10 and 73 ohms depending on float position.
I would start with a reading at sender stud to sender body, work your way to the gauge.
61 F250 Unibody
5.9 Ford Diesel / Allison
Disk brake straight axle
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Toyz
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Re: fuel gauge issues

Post by Toyz »

If your gauge is matched and working properly, and checked while removed, the grounded sending unit should have pegged the gauge when moved to full position. If not, there is a mismatch somewhere, assuming good grounding. If an OEM style float-on-arm gauge, it may be hanging up on something when installed, or as noted, the sender wire is seeing a ground prior to the rheostat. Once working properly, some bending of the arm may be required to "tweak" the arm travel for accurate full and empty readings. I have had very poor luck with the barrel style senders; but I know of no reason to use one with a Mustang tank.
Paul
The Ford Orphanage
Life's too short for boring vehicles!
My quest to develop a universal solvent is held up by the lack of a storage container.
Paul
SLICKCOLLECTOR
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Re: fuel gauge issues

Post by SLICKCOLLECTOR »

Toyz wrote:If your gauge is matched and working properly, and checked while removed, the grounded sending unit should have pegged the gauge when moved to full position. If not, there is a mismatch somewhere, assuming good grounding. If an OEM style float-on-arm gauge, it may be hanging up on something when installed, or as noted, the sender wire is seeing a ground prior to the rheostat. Once working properly, some bending of the arm may be required to "tweak" the arm travel for accurate full and empty readings. I have had very poor luck with the barrel style senders; but I know of no reason to use one with a Mustang tank.
Paul
all 3 gauges could only muster 1/4 tank with arm raised. that is with the sending units out and short gauge wire inside the cab looking at the panel. using my text light probe as a ground and grounding across the stud to the body of the sending unit. my analog gauge could not give me an accurate ohms reading. i think i will go buy a digital meter but all 3 sending units read the same.pegged. does the key switch deliver a full 12 volts to the ivr or is it the 8 or 9 after the resistor wire? or is the gauge in the f600 gauge panel designed for a different current. like i mentioned before the quality of this chinese trash is visibly poor . plastic float etc. after issues with the first 2 i decided to buy a more expensive one but the quality was no better than the first 2. the wire running to the tank is new and i don't think there is any problem with the insulation being stripped etc. i think the factory truck sending for a 65-72 unit is designed for the same current flow as the mustang unit but on a big truck i don't know.. i don't understand the current flow as to how the rheostat works and what ground has to do with the operation of the gauge. thanks for the resident electrical experts. i are not one.

jim
1966 F100 SW 428CJ C6
1965 F100 SW 428 TL sold
1966 F100 SW CVC 428CJ C6
1965 F100 SW CVC 428CJ C6
1966 F100 LB RANGER 390 C6 sold finally
1965 F100 SW CVC 460PI C6
1965 F100 SW CVC 428CJ C6
1972 F100 RANGER XLT SW 428 C6 SOLD
1967 F100 SW CVC 521 C6
1967 F350 390 4 SPEED
1970 F350 428 4 SPEED
1974 F350 428 4 SPEED
1966 F100 523 STROKER C6 GEARVENDORS OVERDRIVE finished
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Toyz
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Location: Baja Houston Taxes
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Re: fuel gauge issues

Post by Toyz »

Jim, clip a jumper from the body of the removed sending unit to a good body ground. Your procedure sounds valid, the plugged in sender should pulse to allow gauge to indicate full. The gauge should register the same with the float arm at full position when removed as when installed, as it should with thew sending wire removed and grounded thru test lamp. I'll look up the big truck tonight; pretty sure it is the same. The IVR sees full available voltage on the input side; the big trucks sometimes had a second resistor wire circuit for the charging system; I don't believe either it or the ignition resistor would be used to feed the IVR.
Paul
The Ford Orphanage
Life's too short for boring vehicles!
My quest to develop a universal solvent is held up by the lack of a storage container.
Paul
SLICKCOLLECTOR
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Joined: January 26, 2007, 8:04 pm
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Re: fuel gauge issues

Post by SLICKCOLLECTOR »

thanks for the suggestion with the chassis ground on the sending unit. after getting everything hooked up the gauge is reading full when empty and empty when full according to the arm, so i thought that is easy to fix so i removed the gauge assembly and reversed the wiring connectors on the back of the fuel gauge. the fricking thing still goes bassackwards. i don't understand it. i checked the voltage on the studs of the gauge with wires attached and both terminals have the intermittent voltage but one is brighter in the other. obviously with more current flowing. is this correct. i don't understand how the gauge operates and the flow of electricity goes from terminal to gauge and terminal to terminal and to the sending unit. thanks again for the electrical wizzards. the sob got me talking to myself. this dash cluster harness is grafted onto the 71 f350 CS wiring harness that had the integral camper with the walk way into the camper between the bucket seats thru the door way into the camper .i also grated a 65 f100 sb onto the 67 sb frame. this POS has parts from a bunch of different vehicles. so anything is possible. i have the dash lites and all gauges looking like they may work and the taillites brake lites and turn signals working on the rear :burp: :burp: :burp: . no grill as of yet. i am sure it will turn over with the key etc.

jim
1966 F100 SW 428CJ C6
1965 F100 SW 428 TL sold
1966 F100 SW CVC 428CJ C6
1965 F100 SW CVC 428CJ C6
1966 F100 LB RANGER 390 C6 sold finally
1965 F100 SW CVC 460PI C6
1965 F100 SW CVC 428CJ C6
1972 F100 RANGER XLT SW 428 C6 SOLD
1967 F100 SW CVC 521 C6
1967 F350 390 4 SPEED
1970 F350 428 4 SPEED
1974 F350 428 4 SPEED
1966 F100 523 STROKER C6 GEARVENDORS OVERDRIVE finished
SLICKCOLLECTOR
Posts: 206
Joined: January 26, 2007, 8:04 pm
Location: eudora ks
United States of America

Re: fuel gauge issues

Post by SLICKCOLLECTOR »

thanks for the suggestion with the chassis ground on the sending unit. after getting everything hooked up the gauge is reading full when empty and empty when full according to the arm, so i thought that is easy to fix so i removed the gauge assembly and reversed the wiring connectors on the back of the fuel gauge. the fricking thing still goes bassackwards. i don't understand it. i checked the voltage on the studs of the gauge with wires attached and both terminals have the intermittent voltage but one is brighter in the other. obviously with more current flowing. is this correct. i don't understand how the gauge operates and the flow of electricity goes from terminal to gauge and terminal to terminal and to the sending unit. thanks again for the electrical wizzards. the sob got me talking to myself. this dash cluster harness is grafted onto the 71 f350 CS wiring harness that had the integral camper with the walk way into the camper between the bucket seats thru the door way into the camper .i also grated a 65 f100 sb onto the 67 sb frame. this POS has parts from a bunch of different vehicles. so anything is possible. i have the dash lites and all gauges looking like they may work and the taillites brake lites and turn signals working on the rear :burp: :burp: :burp: . no grill as of yet. i am sure it will turn over with the key etc.

jim
1966 F100 SW 428CJ C6
1965 F100 SW 428 TL sold
1966 F100 SW CVC 428CJ C6
1965 F100 SW CVC 428CJ C6
1966 F100 LB RANGER 390 C6 sold finally
1965 F100 SW CVC 460PI C6
1965 F100 SW CVC 428CJ C6
1972 F100 RANGER XLT SW 428 C6 SOLD
1967 F100 SW CVC 521 C6
1967 F350 390 4 SPEED
1970 F350 428 4 SPEED
1974 F350 428 4 SPEED
1966 F100 523 STROKER C6 GEARVENDORS OVERDRIVE finished
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Toyz
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Joined: March 22, 2011, 6:23 pm
Location: Baja Houston Taxes
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Re: fuel gauge issues

Post by Toyz »

Looks like you may have to get out the old multi-meter! Sounds like your sender may be the "universal" type instead of the Ford type?????
Paul
The Ford Orphanage
Life's too short for boring vehicles!
My quest to develop a universal solvent is held up by the lack of a storage container.
Paul
SLICKCOLLECTOR
Posts: 206
Joined: January 26, 2007, 8:04 pm
Location: eudora ks
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Re: fuel gauge issues

Post by SLICKCOLLECTOR »

I slept on my dilemma. after further inspection when clamping down a conduit clamp to hold the wires to the frame my new sending unit wire slipped between the clamp and frame and when i tightened it down it grounded out the new wire. repaired that and switched the wires back on the fuel gauge and now it reads empty when installed. thanks for the help.

jim
1966 F100 SW 428CJ C6
1965 F100 SW 428 TL sold
1966 F100 SW CVC 428CJ C6
1965 F100 SW CVC 428CJ C6
1966 F100 LB RANGER 390 C6 sold finally
1965 F100 SW CVC 460PI C6
1965 F100 SW CVC 428CJ C6
1972 F100 RANGER XLT SW 428 C6 SOLD
1967 F100 SW CVC 521 C6
1967 F350 390 4 SPEED
1970 F350 428 4 SPEED
1974 F350 428 4 SPEED
1966 F100 523 STROKER C6 GEARVENDORS OVERDRIVE finished
MNTBUGGY
Posts: 55
Joined: July 17, 2016, 7:55 am
Location: Andale, ks
United States of America

Re: fuel gauge issues

Post by MNTBUGGY »

Hate the Electrical Gremlins !!! Glad you figured it out.
Mike
1966 F100 4x4 SWB
1966 F100 4x4 LWB
1961 F100 Unibody ( Son's)
1969 Chevelle SS-396
1966 Jeep CJ5
1966 Mustang coupe (wife's )
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