Help! Gas Guage Stuck On "EMPTY"
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Freshman User
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Help! Gas Guage Stuck On "EMPTY"
'92 F-150, 302 cid, 2WD:
The gas guage for the front tank is now buried on 'Empty' - REGARDLESS of how much fuel is in the tank. When I flip the switch to the REAR tank, which IS empty, the guage moves up to the 'Full' mark. Odd - the FULL tank reads empty, the EMPTY tank reads full...
I've checked the one fuse for the circuit, and it's not blown. I really don't wanna have to drop the front tank; is there any way to access the sending unit/float WITHOUT removing the tank?
The gas guage for the front tank is now buried on 'Empty' - REGARDLESS of how much fuel is in the tank. When I flip the switch to the REAR tank, which IS empty, the guage moves up to the 'Full' mark. Odd - the FULL tank reads empty, the EMPTY tank reads full...
I've checked the one fuse for the circuit, and it's not blown. I really don't wanna have to drop the front tank; is there any way to access the sending unit/float WITHOUT removing the tank?
Fleet Owner
Joined: Oct 2005
Posts: 20,786
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From: Kentucky
When the gauge always reads empty that means there is most likely a short to ground in the circuit from the front tank. When the gauge floats to way beyond full that means the circuit is open. You can measure the values if you would like at the fuel selector switch in the cab.
This listed for a 1993-1994 but it should be the same for your truck:
The only way to got the Fuel Delivery Module is dropping the tanks or removing the bed.
This listed for a 1993-1994 but it should be the same for your truck:
The only way to got the Fuel Delivery Module is dropping the tanks or removing the bed.
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Freshman User
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Okay...The only problem is, I'm lousy at tracking electrical problems (my father's a Ph.D electrical engineer, and I'm lucky I haven't electrocuted myself yet!) And he's not here to ask, so...
WHAT am I looking for - resistance? Voltage? Which leads do I test? Think of me as an idiot, wiring-wise, and walk me through this.
WHAT am I looking for - resistance? Voltage? Which leads do I test? Think of me as an idiot, wiring-wise, and walk me through this.
Freshman User
Joined: Oct 2004
Posts: 31
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From: Philly
My old 87 bronco 302 always read no fuel, regardless of the fill in the tank. I was about to replace the fuel pump when my vo-tech teacher saw the oil pressure gauge flapping in the breeze. He said, here's your problem, low oil pressure will make your gas gauge do that.
Not sure his reasoning on that if any, but I'm glad I switched classes the next semester all the same.
So hows your oil pressure haha?
Not sure his reasoning on that if any, but I'm glad I switched classes the next semester all the same.
So hows your oil pressure haha?
Fleet Owner
Joined: Oct 2005
Posts: 20,786
Likes: 1,751
From: Kentucky
Okay...The only problem is, I'm lousy at tracking electrical problems (my father's a Ph.D electrical engineer, and I'm lucky I haven't electrocuted myself yet!) And he's not here to ask, so...
WHAT am I looking for - resistance? Voltage? Which leads do I test? Think of me as an idiot, wiring-wise, and walk me through this.
WHAT am I looking for - resistance? Voltage? Which leads do I test? Think of me as an idiot, wiring-wise, and walk me through this.
Set your meter to Ohms. The Full and Empty values are listed in the diagram. You need to measure between a chassis ground and the signal wires. The rear tank fuel level signal is on the Dark Blue/Yellow wire on pin 3 of the selector switch. The front tank signal is on the Yellow/Light Blue wires on pin 1 of the switch. The output of the switch to the dash gauge is a Yellow/White wire on pin 2.
All this is going to do is verify if the signal values are above the listed Full tank value, 145 ohms, or below the Empty value of 22.5 ohms. An open circuit is certainly above 145 ohms, a short to ground is well below 22.5 ohms. By measuring at the switch input and output you can eliminate the switch as the problem.
New User
Joined: Mar 2011
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I have an 89 that was having almost the same problems. The floats were split and full so that they sat at the bottom of the tank. Also the portion that reads the position of the float can wear causing mis readings. only way to get to them is to drop tanks.
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