Need help with gas gauge

[DanEC]

It's possible that 5 gallons might not be enough to register.

I haven't had to work on my ERA's unit, but I've had to fiddle with various tank gage unit over the years to tweak the arm and float where it bottom out just a little off the floor of the tank. Did you look the float over carefully - any chance it's leaking and filling with gas?

The tank should be well grounded to the frame but maybe the gage sender is being isolated from the tank by the gasket. As I remember I had only a single wire hookup on the ERA. But I've got an old Plymouth that actually has a ground strap from the sender tube across the rubber connection hose and tied to the steel supply line. I think my Corvette sender may have a separate ground from the sender unit to the frame or harness. Might try connecting a ground wire to the sender unit steel and see if that helps any.

[RockBit]

Originally Posted by DanEC

It's possible that 5 gallons might not be enough to register.

I haven't had to work on my ERA's unit, but I've had to fiddle with various tank gage unit over the years to tweak the arm and float where it bottom out just a little off the floor of the tank. Did you look the float over carefully - any chance it's leaking and filling with gas?

I checked the float travel while I had the sender out of the tank. It looked right. I did not check to see if the float was leaking. I'll pull it out again tomorrow and check that.

I wondered if the cork gasket was keeping it from making a good ground so I checked that. With the screws into the tank, the ground was good according to my multi meter.

I wonder if this is the right sender for my gauge. I have the Smith's type 4 (from the Wiring Primer) and it says this gauge needs a 350-40 ohm swing type sender. I pm'd Bob a while back and he said I need the SW sender. So one of them is wrong. I get 125 full -25 empty on my sender.

[spdbrake]

When you had the sender out and were checking travel, did you try it connected to the gage? Alligator clip a local ground and run it thru the swing and watch the gage.

This article is the easiest IMO on the swing setup top and bottom of tank.
https://www.hotrodhotline.com/instal...uge-and-sender

I almost bought one of these gage/sender calibrators, but found my issue was the gage wouldn't return to zero (mind of its own) and purchased a Speedhut programmable gage instead.
Classic Instruments Store / SN34
https://www.speedwaymotors.com/Class...ce,230181.html
http://www.classicinstruments.com/us...n%20020116.pdf

Edit
I just re-read you 1st post.
-"when I ground the sensor wire, the gauge reads full." When you ground it your giving the gage Zero Ohms. AKA= low OHMs when full, High OHMs when empty.

Later you wrote.
- "On the bench, the sensor gives 25 ohms at empty and 125 ohms at full(float up). IF so your sender is 180 out from what your gage needs for an input.
It is possible to flip the float (loosen the set screw and run the rod thru from the other side) So that down is up per se. Take a look at the article I 1st posted above from hotrodonline.

[RockBit]

Originally Posted by spdbrake

When you had the sender out and were checking travel, did you try it connected to the gage? Alligator clip a local ground and run it thru the swing and watch

Yes. With the sender out of the tank, I jumpered it to ground and to the signal wire. As I moved the float, the fuel gauge needle moved. I thought I had it solved, but when I put the sender back in the tank, reinstalled the tank, and poured 5 gallons in the tank, the gauge did not move off of dead empty.

I'll read the article. Thanks for your help.