Sending Unit / Fuel Gauge Reading Problem.

[FBODY]

I installed a new tank and new sending unit, since I installed them my gauge doesn't read properly.

The gauge is only reading 3/4 full when the tank is full.  When the gauge reads empty it only takes approx. 8 gallons to fill her up. I therefore have 10 gallons left in the tank when the gauge reads empty.

I have the original console fuel gauge.

My sending unit is a dii Corvex (3/8 Repro from Classic Industries) and the tank is Made in Taiwan P/N 642, CV6003.

I tried two new sending units with the same problem.

Did you guys had this problem? If so, how did you fix it?

Thanks, Daniel.

[BlackoutSteve]

Did you check the ohms resistance of the sender before you installed it?
The ohms reading at empty should be 0-5 ohms, and full should be 90ohms.
I bench tested my repro sender before installing it at it would only go to 3/4 full also.
However, empty was in fact empty.
I had to modify the float stop on the sender to allow more travel to gain 90 ohms.
Typical repro stuff.

http://forums.hotrod.com/ubbthreads/showflat.php?Cat=0&Number=132290&an=0&page=2#132290

[FBODY]

Thanks for the info Steve,

Both measured Ok when new out of the box.  They both changed value when installed in the tank, with fuel in the tank and the car running.  On both the resistance became lower.

I'm think of dropping the tank for the 3rd time to bend the rod or to replace it with a new GM one.

Thanks, Daniel.

[BlackoutSteve]

Check all your electrical connctions first.
Maybe it's possible your ground is not as good as it could be or the sender's connection into the rear loom is not real great..

[johnny68]

im having the same type of problem on my 68 camaro. when the tank is full, the gauge reads way past full, and when the gauge reads full i figure that it is about half full in the tank. also the last time that i filled the tank to thr top, gas leaked from the top of the tank.

[GIBSTER]

Mine was doing something similar, The pickup tube where it comes up out of the tank was not attached good to the round flat base, (where it is crimped on) I guess making a bad ground.

[dab67]

Problem i have with my is that when the tank begins to empty the needle on the gauge bounces back and forth. Almost like the sending unit is "floating" inside the tank.  What's up with that!!!!!!!!!!!!!!!!!!!!

Dave

[rat pack]

Guys I have found all of these problems to be very common with the reproduction sending units, especially the Corvex/Dynacorn (they are brothers) units. I have had to solder the lines to the ring, bend the float arms, etc. to no avail. There is really no cure for it except to have your original rebuilt or pay for the GM unit if it is still available for your application. Just recently the 68-9 single 3/8" line (no return line) GM unit has shot through the ceiling as for price, almost $175.00, if it hasn't been discontinued by now. Year One offers a great rebuild service for your originals, and its cost is cheaper than buying an NOS unit in some cases. Also I believe they have found a new vendor that makes them in stainless steel with the prices being along the same lines as the GM units.............RatPack.................

[FBODY]

I installed a Spectra Premium Sending Unit P/N FG104C (3/8 Single Line), from NAPA, this spring and it works fine.

Good Luck, Daniel.