Goofy gas gauge even after new sending unit!!!

[Chrisoswald]

Originally Posted by j.mccreight@hotmail.com

Since your issue is with the fuel gauge I would concentrate on that. Disconnect leads from sender and disconnect leads from gauge and then measure the resistance of each wire seperatly one to gauge the other to a good ground on engine or battery anything less than .5 ohm is ok, make sure you disconnect battery first. You could also run a new signal wire from the sender to the gauge as a trouble shooting method. Ensure the gauge is getting full battery voltage and ensure the ground on gauge is also good. On a tristar there is a large wire junction about 12 wires iirc, on the rear of engine near the bilge, check that and clean as necessary. fairly simply circuit, sender has a ground and a signal, the gauge has a power, ground and the signal and then the light circuit.

I am determined to fix this so thanks a ton for taking the time to help. I understand what to do however I'm stumped a bit. And I may show some ignorance here but when I touch the two leads at the sending unit together the gauge pegs way past full. I assumed that would also means that the wiring was good but clearly this is not the case. Can you help me understand why?

[mikeg205]

When you touch the 2 leads at the send unit your taking the resistance to 0. The sending unit is a variable resistor. Low resistance tells the gauge the tank is full....no resistance pegs the needle.

follow this and you will have your masters degree in fuel senders and gauges. Like suggested before measure the resistance at the sender. So multimeter red probe to sending wire black to ground wire. Then measure signal at gauge...signal wire to ground

[j.mccreight@hotmail.com]

Originally Posted by Chrisoswald

I am determined to fix this so thanks a ton for taking the time to help. I understand what to do however I'm stumped a bit. And I may show some ignorance here but when I touch the two leads at the sending unit together the gauge pegs way past full. I assumed that would also means that the wiring was good but clearly this is not the case. Can you help me understand why?

check your p.m.'s

[Chrisoswald]

Got it all sorted out. Turned out to be a bad gauge....got lucky and found a vdo exact OEM matching gauge. HUGE thanks to j.mccreight for taking time out of his day to call me and walk me down the path of getting this fixed.