Fuel gauge reading OK until I switch to ignition

[darkzebra]

My fuel guage will read OK when the car is off, but jumps to empty as soon as I start the car. The inset quarter tank gauge continues to work fine. The connections at the tank looks fine, with no corrosion.

 

I did change to a Walbro fuel pump, which has its own separate circuit. However, I set the walbro relay to be triggerred by the OEM fuel pump relay - which seems to allow it to cut off if you switch to ignition and don't start.

 

Any suggestions? Maybe I connected the Walbro incorrectly?

[roger.svoboda]

somehow you connected the power for the fuel sender into a relay (maybe?) or crossed into the igntiion wiring somehow. what you have done is cause it to lose power which is why it goes to zero. you need to do some work tracing wires in the schematic and figure out what you did. you didn't note what year car nor type of dash you are asking about. that information helps to get answers.

[darkzebra]

Thanks!

 

It is a 1982 280ZX turbo, with analog combo gauge.

 

As I remember I ran new power wire to a 30A fuse then a 30/40A relay, then to the pump. The pump was grounded to frame. The relay was originally triggered by ignition. I noticed the pump would continue to run even if I did not start. So I switched my new pump relay to be triggered instead by the original fuel pump relay (the one behind the fusible link).

 

I will check it tomorrow, but maybe if you or anyone else can tell me the correct way to connect a Walbro fuel pump to the 82 280ZX I can try that and see if it corrects itself.

Edited September 26, 2010 by darkzebra

[wagon jon]

If the previous suggestions don't work, try placing the old unit back in to see if it is reading fine. If so, then the wires could be switched.