gas gauge adjustment

[ROKuberski]

Every since I got my car, the gas gauge was inaccurate.  Part of the problem came from a new sending unit I got from Concours Parts.  It had the wrong ohm range and, according to their "expert" the resistance range made no difference.  The ohm range for this car should be 73(E) - 10(F) ohms.  The one they sent me measured 118 - 20.  NG!

Also, the gauge itself seem to have a problem.  With the ignition off, the needle dropped out of sight, with max voltage, it made it up to about 1/2 full.  The needle also had a sloppy trip as it moved up the scale. 

Well, I finally ordered the correct range sender and while waiting for it to arrive I've taken the gauge out and opened it up and found that there are two adjustments inside.  I have some resistors and a 5 VDC power supply so I set it up so I could simulate empty and full.  The adjustments allow you to work on both ends of the scale and I've now got it working accurate to within 1/2 of the needle with on each end of the scale.  The photo shows the inside of the gauge.  Note the two small holes with a short flat notched plate near the holes.  Put a small screwdriver in the holes and you can move the notched plates.  It took several adjustments to get it right.  By moving towards the full end it also affects the adjustment on the empty end.  With a few adjustments, all was fine.

The worst part of the project?  Removing the gauge cluster. 

I've had the car 7 years now and only ran it out of gas once.  I usually keep it at least 1/2 full.  Hopefully, wondering about fuel supply will be a thing of the past.

[fdlrc]

Very interesting, thanks.

[lalessi1]

I adjusted my gauge a while back using the hole in the back and a small screwdriver. I would be willing to bet that the temp gauge has a similar set up.

[ROKuberski]

Lynn,

I'll bet you are right.  If I had more information on how that gauge was calibrated, I would give that a try too.  I think mine reads a little low, but not positive.  Since I've got the gauge console ripped apart, it would be easy to do. 

The only thing I could do would be to set the needle to read correctly at the cold setting and them put the sending unit in boiling water and set the needle to read normal.  Water boils at about 196 in Denver.

I finally ordered the parts to install EFI in my car.  I selected the Holley Sniper unit using the FiTech Command Center 2 unit for fuel delivery.  Parts should show up Friday.  I'll make a video of the process and post it on youtube.

Rich