Ever since changing over the VDO gauges, I have a fuel level gauge problem. My VDO gauge works, but the range is off. With a full tank, the gauge reads half. However, when the tank is almost empty the gauge reads just a hair above empty. What do I need to do in order to get the gauge to show the full range of operation? Is it a different sender that is needed?

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84 2.5
87 328 GTB replica.
87 Coutach replica

The stock sender will send a resistance of 0 ohm when empty and 90 ohms when full. Is this what the VDO gauge is looking for? If so then it sounds like your sending unit is having problems. You can check the actual resistance of the sending unit at the yellow connector on the firewall, in the engine compartment behind the passengers seat. Measure between the Black and Purple wires.

You did disconnect the stock gauge correct?

quote Originally posted by phonedawgz: The stock sender will send a resistance of 0 ohm when empty and 90 ohms when full. Is this what the VDO gauge is looking for? If so then it sounds like your sending unit is having problems. You can check the actual resistance of the sending unit at the yellow connector on the firewall, in the engine compartment behind the passengers seat. Measure between the Black and Purple wires. You did disconnect the stock gauge correct?

Yes, the stock gauge was removed. The VDO is apparently linear, meaning that it doesn't stay at full for a long time and then drop like a stone. Full tank reads half on the gauge. Half tank reads a quarter and empty is just that. I'll measure the resistance at the firewall.

You have to have the correct matching sender and gauge or it will read wrong. I put one in my Coronet.

My new VDO fuel gauge is also off but I have a known sender problem. The tank emptied at 1/3 full with the stock gauge and is now empty somewhere around 1/2 tank. If I replace the sender, I bet that the gauge will work correctly.

Nelson

quote Originally posted by Joe 1320: Ever since changing over the VDO gauges, I have a fuel level gauge problem. My VDO gauge works, but the range is off. With a full tank, the gauge reads half. However, when the tank is almost empty the gauge reads just a hair above empty. What do I need to do in order to get the gauge to show the full range of operation? Is it a different sender that is needed?

Sounds as if your gauge is not for the Fiero sender of 0 to 90 ohms. Sounds like you got the VDO gauge that has a 10-180 ohm range, which would give you a reading of 1/2 tank when the tank was really full.

quote Originally posted by Joe 1320: Ever since changing over the VDO gauges, I have a fuel level gauge problem. My VDO gauge works, but the range is off. With a full tank, the gauge reads half. However, when the tank is almost empty the gauge reads just a hair above empty. What do I need to do in order to get the gauge to show the full range of operation? Is it a different sender that is needed?

if you contact the VDO dealer that sold you the gauge, he should be able to provide you with another gauge with the same trim package that will work with the stock GM sender.