Gas gauge/sending unit problems
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Gas gauge/sending unit problems
Hello. Just recently installed a new SPI gas tank in my 75 F150. It's the 22.5 gallon long tank part number F25A and sits in front of the rear axle lengthwise with the side frame rail.
It also has the 19 gallon rear tank.
At the time i installed a new spi FG73A sending unit.
No matter what i do i can't get the gas gauge to raise over E and i've put about 12 gallons in it so far.
I unplugged the wiring harness from the sending unit and confirmed the pulsing voltage at the connector . Once I grounded the positive feed the gauge went up over full as it should...this confirmed that the gauge and dash voltage regulator were in fact working.
I removed the sending unit to bench test it. With a digital and an analog ohm meter attached the raising and lowering of the float did not record a reading.
I purchased another sending unit and upon testing it on the bench it initially did the same thing but after many swings up and down on the float arm it finally started to read ...seems as if the contacts had maybe a coating on them..
Anyway, the sending unit spec'd at roughly 10-90 ohms.
Put it in the vehicle and it doesn't work...i'm at a loss...
I note on www.rockauto.com that the FG73A is the required sending unit for the rear mounted tank..19gallons..but doesn't mention the 22.5 gallon front tank.
Is there a different sending unit made for this tank? The supplier here looked it up again and confirmed that the only one listed is the FG73A...
IIRC...now that i remember the bend in the float arm may have been a tad different but it was in the same linear plane and should rise in the tank...i may have been mistaken though..i don't have the old one to compare..
Any help would be appreicated...thanks...John
It also has the 19 gallon rear tank.
At the time i installed a new spi FG73A sending unit.
No matter what i do i can't get the gas gauge to raise over E and i've put about 12 gallons in it so far.
I unplugged the wiring harness from the sending unit and confirmed the pulsing voltage at the connector . Once I grounded the positive feed the gauge went up over full as it should...this confirmed that the gauge and dash voltage regulator were in fact working.
I removed the sending unit to bench test it. With a digital and an analog ohm meter attached the raising and lowering of the float did not record a reading.
I purchased another sending unit and upon testing it on the bench it initially did the same thing but after many swings up and down on the float arm it finally started to read ...seems as if the contacts had maybe a coating on them..
Anyway, the sending unit spec'd at roughly 10-90 ohms.
Put it in the vehicle and it doesn't work...i'm at a loss...
I note on www.rockauto.com that the FG73A is the required sending unit for the rear mounted tank..19gallons..but doesn't mention the 22.5 gallon front tank.
Is there a different sending unit made for this tank? The supplier here looked it up again and confirmed that the only one listed is the FG73A...
IIRC...now that i remember the bend in the float arm may have been a tad different but it was in the same linear plane and should rise in the tank...i may have been mistaken though..i don't have the old one to compare..
Any help would be appreicated...thanks...John
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Sending unit problems
Nope...Mark..not the ground. I ran a separate one and made sure the tank was grounded too.
I think i figured it out. I think i have the wrong sending unit in there.
The tank and sender i bought was an spi unit.
Once i checked Rockauto and my local parts supplier i noted that there is only 1 sending unit available for that year truck and in the fine print it states 'for 19gallon rear tank'..yet the front midship tank has a definite different sender.
Upon checking LMC trucks on line i noted that the steel side tank takes a different sending unit, so i ordered it.
It's strange that i've checked so many suppliers and they all stock the one sender and do not make any references to the side or rear tank...
Hopefully this will work....thanks...John
I think i figured it out. I think i have the wrong sending unit in there.
The tank and sender i bought was an spi unit.
Once i checked Rockauto and my local parts supplier i noted that there is only 1 sending unit available for that year truck and in the fine print it states 'for 19gallon rear tank'..yet the front midship tank has a definite different sender.
Upon checking LMC trucks on line i noted that the steel side tank takes a different sending unit, so i ordered it.
It's strange that i've checked so many suppliers and they all stock the one sender and do not make any references to the side or rear tank...
Hopefully this will work....thanks...John
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 784
From: Simi Valley, CA
I think i figured it out. I think i have the wrong sending unit in there. The tank and sender i bought was an spi unit.
Once i checked Rockauto and my local parts supplier i noted that there is only 1 sending unit available for that year truck and in the fine print it states 'for 19 gallon rear tank'..
yet the front midship tank has a definite different sender.
Once i checked Rockauto and my local parts supplier i noted that there is only 1 sending unit available for that year truck and in the fine print it states 'for 19 gallon rear tank'..
yet the front midship tank has a definite different sender.
Fits: 1970/79 F100/350 2WD Regular Cab Styleside with mid-ship Fuel Tank.
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