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I have a 1979 F150. I can’t get the gas gauge to read right. It has a new tank. I tried two new sending units and new wiring. I also changed the voltage regulator. The only thing that has not been replaced is the gauge itself. When I start the truck it goes to above the full line then slowly drops back down to around 1/2 - 3/4. It doesn’t matter how much gas is in it that’s what it always reads. It seems like a sending unit issue. The first was a ebay one. The new one in it now is from bronco graveyard. The gauge moved a little more with the first unit but was never right. The one now moves even less. I was considering bending the sending unit some. Maybe it’s not moving enough to make the gauge go from empty to full. The truck has a 460 with 4.56 gears. It doesn’t get the best mileage. I need the gauge to work accurately.
I have a 1979 F150. I can’t get the gas gauge to read right. It has a new tank. I tried two new sending units and new wiring. I also changed the voltage regulator. The only thing that has not been replaced is the gauge itself. When I start the truck it goes to above the full line then slowly drops back down to around 1/2 - 3/4. It doesn’t matter how much gas is in it that’s what it always reads. It seems like a sending unit issue. The first was a ebay one. The new one in it now is from bronco graveyard. The gauge moved a little more with the first unit but was never right. The one now moves even less. I was considering bending the sending unit some. Maybe it’s not moving enough to make the gauge go from empty to full. The truck has a 460 with 4.56 gears. It doesn’t get the best mileage. I need the gauge to work accurately.
I didn't see a mention of the ground connection verification. that's probably the most important part of the equation. Which voltage regulator did you change? The one that regulates to ~5v specifically on the instrument cluster? Do your oil and water temp gauges read correctly?
Since you are already familiar with R&I of the tank sending unit, I'd hand check simulated fuel levels with the sender out of the tank.
Before you go replacing the gauge itself, see what it ohms at with key off but everything connected at the two terminal posts for the gauge (at the printed circuit)-flip your aux/main switch (I assume you have one) and move the float up and down. verify ohms in all cases.
I didn't see a mention of the ground connection verification. that's probably the most important part of the equation. Which voltage regulator did you change? The one that regulates to ~5v specifically on the instrument cluster? Do your oil and water temp gauges read correctly?
Since you are already familiar with R&I of the tank sending unit, I'd hand check simulated fuel levels with the sender out of the tank.
Before you go replacing the gauge itself, see what it ohms at with key off but everything connected at the two terminal posts for the gauge (at the printed circuit)-flip your aux/main switch (I assume you have one) and move the float up and down. verify ohms in all cases.
Yeah, I changed the instrument cluster voltage regulator. Someone cut the wires to the temp and oil pressure and installed aftermarket gauges years back. I plan on dropping the tank soon and see what I can come up with.
Sending unit plug should have both ground and gauge feed wire. Seems no one has good results with aftermarket senders. You can have your original rebuilt. Check for rebuilders in Hemmings magazine.
Have you not hang tested the new sending unit BEFORE you put it in the tank and put the tank in? Wire hang the sending unit, from the cross member. Plug it in, ground it. Turn the key on, and have a person move the float, does the gauge react? Also Omh it out. Right sending unit for correct size (gallon) tank?
Have you not hang tested the new sending unit BEFORE you put it in the tank and put the tank in? Wire hang the sending unit, from the cross member. Plug it in, ground it. Turn the key on, and have a person move the float, does the gauge react? Also Omh it out. Right sending unit for correct size (gallon) tank?
I dropped the tank today. The sending unit was fried. I checked the voltage at the sending unit and it was 12 volts. It has a new voltage regulator at the gauge so it should be 6 volts. Also, I put a test light on it and it did not pulse. So it must not be working. Is there anything that can ruin a new voltage regulator? Or maybe it’s just aftermarket junk.
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