S14 Fuel Level Sender Fix

[Alch]

After a spirited autocross in my 95 S14 240sx I discovered that my fuel level sender had fallen off its mount and down into the gas tank. Consequently, my fuel level gauge hasn't read properly for the past few months since I didn't have a lot of spare time to work on the car.

I plan on going in and reattaching the sending unit to it's proper position, but before I do this I have a few questions.

On a whim I tried to do this a while back only to discover that I didn't have the proper tool to unscrew the lock ring that holds the fuel pump in place. I searched around when I was doing this since I know people replacing their stock pumps with Walboro pumps must encounter the same problem. But, as I expected, the only thing I seemed to find was that people get the ring off with a hammer and a screw driver. I don't like this idea one bit. (Stripping and breaking parts is no fun.) Recently while wandering through the plumbing section of Home Depot I found a lock ring wrench that looks to be just the thing for the job. I'll report back if it works.

My question is this: when I read through the FSM on how to open up the fuel tank and deal with the fuel pump and sending unit it says that when you open up the tank you should replace the O-ring that seals the tank. Where can I purchase a new o-ring? It seems fairly large. Are these available at Autozone or Oreilly or am I going to have to pay an arm and a leg to Courtesy Nissan and delay my plans?

If I can't find a new o-ring locally, would it be reasonable just to lube up the old o-ring with some petroleum jelly and re-use it?

Second, Since it seems like the fuel level sending unit fell off of its mount fairly easily just autocrossing, I would like to do something to prevent this in the future. Does anyone have experience with safety wiring, and if this would be an acceptable thing to do in an environment such as the gas tank?

Update:

I purchased this lock ring tool from Home Depot. It helped me break the lock ring free a little, but the angle of the combination of the angle of the inspection hole and the depth at which the lock ring sits made it very difficult to use this. In addition, the lock ring is plastic and so the tool managed to chip the lock ring a bit. After getting the ring moving a little I went after it with the rubber coated handle of my pliers and a dead-blow hammer.

Upon getting the gas tank open I found, as I had suspected that the fuel level sender unit had fallen off of it's mount. What I didn't realize was the manner in which the fuel level sender is mounted. After much struggling and contorting myself in the tiny S14 trunk I managed to slide the sender back into the bracket mounted inside of the gas tank. In retrospect I think I could've rapped some safety wire around the bracket to try and insure that the sender would not slide out again, but it felt as if unit snapped in and was solidly held in place. (I also forgot to go purchase some wire.)

A quick reassembly and reattaching of all the hoses led to a short test drive. No apparent leaks, and all of a sudden my fuel gauge dropped down from 100% full to almost empty. (I waited until i had very little fuel in the tank so that I didn't have to dip my hand into it).
Modified by Alch at 7:54 PM 6/6/2008

[Fairlady280Z]

I have the same problem with my 95 S14 as well, i even made a thread but didnt get much help

zerothread/341816

When i opened up my tank my floater was just floating in the tank (my problem was that my gauge would stay at F, this explained it) I grabs the floater and put it onto where i thought its supposed to mount. It was hard to see anything as my tank had more gas than i estimated in it and made it very hard to see anything and feel around especially with the gas burning my entire forearm. Anyway i put it on and put everything else back and when i started driving my gauge went to 1/4...i drove another 30 miles and it didnt move, so i filled my tank and it went to F, ive already driven 100 miles on this tank and its still near F...so i think i may have mounted it wrong, do you have a pic or maybe draw up a diagram of how its supposed to mount? i just kinda felt around with it till i felt it slide onto what i assumed was its bracket, when it was on there it was really lose, is there something that hold it in place as well? thanks