Gents

In the process of finishing up my restoration and Ive hit a snag. I bought a new sending unit for the tank as the old one basically fell apart. Tested it outside the tanks and it work flawlessly with the new gauge. Put it in the tank with five gallons of fuel nothing zero. Pulled it out, tested again. Made sure the tank is isolated - it is. Still nothing when installed. Anyone run into this problem?

Sending unit is the two wire available from zcardepot.

Edited August 14Aug 14 by Pomorza

Did you test the gauge by grounding the wire from the gauge itself. It should move all the way over to full.

3 hours ago, Yarb said:

Did you test the gauge by grounding the wire from the gauge itself. It should move all the way over to full.

Yes I have confirmed the gauge works. It also works when the sending unit is not in the tank.

So, Are you saying that when the gauge is hooked up outside the tank and you maneuver the arm the gauge works properly?

The new Nissan sending unit I put in my 240 is 5 gallons sitting on empty. I was in such a hurry to get away from the fuel tank and all the mess involved I forgot to compare it to the original and bend the rod to match. Oh well...5 gallon reserve when it hits empty.

3 hours ago, Yarb said:

So, Are you saying that when the gauge is hooked up outside the tank and you maneuver the arm the gauge works properly?

Yes, if I pull the sending unit out of the tank and maneuver the arm the gauge works perfectly. If I reinstall the sending unit back into the fuel tank it reads nothing.

I'll add fuel and see if perhaps 5 gallons is not enough to move the needle, it should as that's roughly 1/3 of a tank.

As @siteunseen mentioned you may have to manipulate that arm. Add a gallon at a time until it starts to read on the gauge and go from there. IMO

7 hours ago, Yarb said:

As @siteunseen mentioned you may have to manipulate that arm. Add a gallon at a time until it starts to read on the gauge and go from there. IMO

I figured it out, just needed a DMM. The stock sending unit is 10-12Ω full and 90Ω empty, the new sending unit is 13Ω full and 105Ω empty. The gauge I use has a standard setting of 0Ω full and 90Ω empty, meaning with this set up, it'll show empty before the car actually gets empty, which to me is completely fine.

Thanks everyone!

Pomorza, i'd also recommend to apply some fuel tank JB Weld epoxy to the inside/outside of that one connector with the rubber washer. I had to replace the brand new sending unit with another one from zcardepot, because someone overcrimmed the rubber washer inside of it. My car had a big fuel leak at the car show when I filled up the tank full. The replacement unit looks better, but i don't want to take any chances.

2 hours ago, darom said:

Pomorza, i'd also recommend to apply some fuel tank JB Weld epoxy to the inside/outside of that one connector with the rubber washer. I had to replace the brand new sending unit with another one from zcardepot, because someone overcrimmed the rubber washer inside of it. My car had a big fuel leak at the car show when I filled up the tank full. The replacement unit looks better, but i don't want to take any chances.

Thanks for the suggestion. I bought a new one so it shouldn't be that difficult to do.

Be very careful using JB Weld. There’s no return