need help from gage guru's please

[smlveightis]

After alot of reading on this site about electrical/gage/dash problems, I decided to do some work on my car.
The car-'67 barracuda with dealer added a/c, 273 4v engine, complete fuel system replaced 10 yrs. ago (gas tank w/sump, electric pump, chrysler sending unit, all fuel lines, regulator, filters, & carb).
The problem-temp gage had stopped working a little while back, and the gas gage hasn't been accurate since I bought the car, and thus replacing the complete fuel system 10 yrs. ago.
After removing the dash, I found numerous loose connections on the back of the printed circut board. Tightened up all loose connectors, replaced all dash bulbs w/new bulbs, and re-installed dash. The temp gage works now, but the gas gage still is inaccurate. It shows empty after using about 7-8 gallons of gas. Has anyone got any ideas what could be the culprit on this one?

 

[69signetv8]

It's nice when everything works!!
Just a stabb - Even though replaced 10 years, it sound to me like your "sending unit" is acting up. You say when it's full..it reads full, however after about 8 gallions use or so it reads MT. My guess is that if your sending unit is a float design the float arm is loosing contact with the "resistance wire" (in the contact shoe box in the tank). When the gas drops it gives you a wrong indication or no indication at all (MT). Firstly, your getting your 12 volts at the tank because your guage shows full at full. Take the connection contact off the tank and the guage should drop to MT. Now before you go ahead and rip out the sending unit...you could just get "any" old sender and dry connect the voltage wire to the contact. (ensure the unit itself is grounded) then move the float arm up/down while someome is watching your guage. If it works..your unit is hosed...if not, then yes possible guage problem (ripping out the cluster sucks)

 

[smlveightis]

Thanks for the reply. It definately gives me a direction to go in.

 

[a68postcar]

69signetv8 nailed this one down pretty well. p/s don't forget to drain your tank before removing the offending sender. gas in the face sucks!