Gas Guage question
Posting Guru
Joined: Jun 2004
Posts: 1,635
Likes: 0
From: Niceville, FL.
If the gauge works ok for a portion of its range and then goes to empty it's most likely a break in the resistance wire inside the sender. Erratic operation can be wear in the sender "wiper" arm where it contacts the resistance wire, in the sender internal ground path or poor electrical connections external to the tank. Inaccuracies over and above the built-in inaccuracies due to tank shape can be due to poor connections, bad floats, bent float arms, or the wrong replacement sender installed in the tank.
Lead Driver
Joined: Dec 2002
Posts: 5,491
Likes: 16
From: Kuna ID
Both of my tanks read only the top half, when it says empty I usally still have 8-9 gallons left. I went to the scrap yard and got a speedo with the trip odometer in it. Now I just know to either swap tanks, or fill up every 150 miles. 
Senior User
Joined: Jun 2003
Posts: 390
Likes: 0
From: Rose City, MI
probsbly does have some issue. I put it in about a year ago after i discoverd my old one leaking at the elbow. got it from ford for a little over 60 dollars. maybe next weekend i will drop the tank and see whats up.
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Junior User
Joined: Jan 2004
Posts: 88
Likes: 0
Originally Posted by Piffery1
I have the JC Whitney sending unit on my '83 F350 with 22 gallon mid-ship (outside frame) tank. Its five screw mounting matched my tank exactly. Don't know if you could convert a Ford sender to use the Whitney electrical parts though. When mounting the unit you have to adjust the float arm length and pivot point position. At Empty I have ~3 gallons remaining and at 20 gallons guage reads Full. Can't remember exactly but I think 13 gallons registerd 1/2. The resistance part of this era Ford gauges (0-80 Ohms) are all the same I think so you can swap those parts around but float arms vary considerably. If you take one apart be very careful; the resistance wire is very, very fragile. On all 0-80 Ohm Ford sending unit (oil pressure, fuel, water temp) 73 Ohms make the gauge read at low mark and 10 Ohms at high mark according to my ford manual.
Posting Guru
Joined: Jun 2004
Posts: 1,635
Likes: 0
From: Niceville, FL.
mopar,
It just about has to be something in common with the instrument panel voltage regulator. My guess is the ground circuit through the printed wiring connector on rear of instrument panel is intermittent. If the regulator loses its ground its output would go to full battery voltage and likely cause the gauges to go to maximum. I'd try running a separate ground wire from the instrument voltage regulator mounting tab to the cab metal.
It just about has to be something in common with the instrument panel voltage regulator. My guess is the ground circuit through the printed wiring connector on rear of instrument panel is intermittent. If the regulator loses its ground its output would go to full battery voltage and likely cause the gauges to go to maximum. I'd try running a separate ground wire from the instrument voltage regulator mounting tab to the cab metal.
Junior User
Joined: Aug 2003
Posts: 63
Likes: 0
I took both tank sensors out repaired the holes in the float, cleaned resistor trace and wiper and calibrated with the service manual procedure. When I filled the tank my readings we 2 gallons got the needle to the E (20 miles before dry in my guzzler). Half tank was 9.5 gallons 3/4 was 14 gallons. From the 3/4 to F reads any where from E to F because the circuit resistance trace is worn out at that area. Also cleaned the contacts on the dash flex circuit. After years of guessing when the tanks were empty. I now know exactly when I'll run out of gas and I push it everyday now that gas is above 2.10.
New User
Joined: Jun 2005
Posts: 9
Likes: 0
my front tank works great to about a quarter tank... then it reads empty. the rear tank doesnt read at all, just a dead needle. to tell you the truth i dont care much whether it works or not, since i'll never drive it far enough to use a whole tank in one trip.
Post Fiend
Joined: Jul 2004
Posts: 8,786
Likes: 28
From: Northern California
Mopar,
Mine does the same thing, I've been lazy though and just hit the top of the dash and the ground connection returns.
I was thinking about getting a new circut board to fix it though.
Mine does the same thing, I've been lazy though and just hit the top of the dash and the ground connection returns.
I was thinking about getting a new circut board to fix it though.
Post Fiend
Joined: Jan 2000
Posts: 5,330
Likes: 17
From: Dryden, ON, Canada
The guage reads backwards on the front tank in my F250... below empty is full, and 3/4's of a tank is you shoulda got gas 5 miles ago... LOL
My 81, the guage is sort of accurate up to 1/4 tank, from there up, well, 90% of the time, it doesn't go past 1/4... I figure the sender is probably worn and the truck was re-fueled at 1/4 tank most of the time.
My 81, the guage is sort of accurate up to 1/4 tank, from there up, well, 90% of the time, it doesn't go past 1/4... I figure the sender is probably worn and the truck was re-fueled at 1/4 tank most of the time.
Last edited by 82F100SWB; Jun 22, 2005 at 08:08 AM.
Posting Guru
Joined: Nov 2004
Posts: 1,137
Likes: 2
From: Asheville, NC
My '84 had a bad tank sender due to the idiot that worked on the alternator regulator wiring. He shorted the regulator and caused about 18 volts to run rampant thru the electrical system for a day or so. Burned out most of the lights in the display, and the turn signal flashers. When he finally fixed it, the charge light no longer worked. He had 'engineered' the alternator wiring harness for a gauge system into this truck. Idiot. When I bought the truck, I pulled an alternator harness from an 81 / w/light, and installed it along with the correct regulator that I found under the seat.
I drove this truck for 12 years with no gas gauge. I kept track of the gas by checking the odometer. BTW: The speedometer didnt work either, when I got it. Same mechanic. He messed up the speedometer gears in the transmission when he didn't properly remove the tail-shaft bearing. The bearing just slopped alover the place.
He is still in "business." I dont go there at all.
I drove this truck for 12 years with no gas gauge. I kept track of the gas by checking the odometer. BTW: The speedometer didnt work either, when I got it. Same mechanic. He messed up the speedometer gears in the transmission when he didn't properly remove the tail-shaft bearing. The bearing just slopped alover the place.
He is still in "business." I dont go there at all.