I recently rewired my wifes 1959 xk150 FHC with a new complete wiring harness from Rhode Island Wiring Service Inc. (excellent quality harnesses ). Prior to rewiring, the gas gauge would always show a full tank as soon as you would turn the key on even though it did not have a full tank . I assumed their was a short in the wiring system and the problem would be resolved after the new harness was installed . I was wrong the gauge still jumped to full as soon as you turned the key. I did just replace the sending unit in the gas tank with a new one and this is still not the problem as the gauge still jumps to full as soon as you turn on the ignition. Does this sound like the gas gauge has to be rebuilt ? Any advise would be appreciated thank you Bill Breheny

Submitted by NE08-63766 on Thu, 08/23/2012 - 15:37

Hi George,
Yes, you're right, it was 220KB, I thought I could sneak it by so I sent it via e-mail. I also sent him the link to Nisonger.

Regards, Otto

Submitted by NE08-63766 on Wed, 08/22/2012 - 05:51

Hi Bill,
If the gauge read full before the wiring & sending replacement, then also after, I would look @ the gauge for the answer. The sending unit is just a big resistor, ground goes in, adjusted ground goes out. It would appear you have solid ground in one of the 2 wires from the gauge to the tank. The center of the gauge should have a GR/YEL wire, looking at one side, there should be 3 solid GR wires, that's the HOT feed, the other side post will have the GR/BK wire from the sending unit. The GR/YEL on the center post will light up the low fuel warning lamp & since it doesn't go on, I would check the GR/BK.
If you are able to move the sending arm up & down & using an OHM meter, check & see if you get the needle of the meter moving. If the needle moves then it's the gauge that needs repair. If the needle stays solid then there is a dead short to GRD in the circuit. I've enclosed a photo of the sending unit, from a friend who restored his 150.

Submitted by NE08-63766 on Wed, 08/22/2012 - 05:48

Hi Bill,
If the gauge read full before the wiring & sending replacement, then also after, I would look @ the gauge for the answer. The sending unit is just a big resistor, ground goes in, adjusted ground goes out. It would appear you have solid ground in one of the 2 wires from the gauge to the tank. The center of the gauge should have a GR/YEL wire, looking at one side, there should be 3 solid GR wires, that's the HOT feed, the other side post will have the GR/BK wire from the sending unit. The GR/YEL on the center post will light up the low fuel warning lamp & since it doesn't go on, I would check the GR/BK.
If you are able to move the sending arm up & down & using an OHM meter, check & see if you get the needle of the meter moving. If the needle moves then it's the gauge that needs repair. If the needle stays solid then there is a dead short to GRD in the circuit. I've enclosed a photo of the sending unit, from a friend who restored his 150.