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This topic has been covered many times over the years. My apologies for repeating. After 69 years my fuel gauge needle is all over the place and currently shows empty and is actually full. The needle moves when I swerve the car though. I surmise it is the sending unit. I have a new vendor unit and a Spectra Premium FG97A. Trivial question. I have not been under the car in a while. Is the unit accessable without dropping the tank? Any help would be greatly appreciated. A diagram as well.

Regards
TC

It sounds like the sending unit itself is electrically functional but the float has failed. In the car's original configuration you'd have to drop the tank to access the unit unless someone subsequently cut an access hole in the trunk floor.

Interesting color choice on the rig by the way

Also as someone mentioned earlier, you can often fix a pinholed float with a torch and some solder, once it is empty of course.

Agree it is probably the sender and in addition to the float it could also be the fiber support the resistance wire is wound on inside the sender. That support could have warped and there is intermittent loss of contact with the wiper as the float moves it across the resistance wire. Usual symptom there is the tank reads then gets very erratic or drops to empty. It may start to read again and then after a few more gallons are used it may start to jump around again.

If the car is stock then trunk has never had a hole cut in the trunk floor to access the sender and the tank will need to drop. With a full tank of gas that will be a pain and a bit dangerous. The service shop of a Ford dealership went up in flames here a few years ago when a mechanic tried to remove a full tank and it was dropped.

To drain the tank you will need to remove the drain plug and if the plug has been in place for years or never been out there is every chance it is rusted in place and you need to take some precautions before and when trying to remove it. The original plug is steel and threaded into a steel bung pressed in a hole in the sheetmetal tank and then a thin bit of the bung is crimped over the hole on the inside to hold it on. Assuming plug is rusted, first use a good penetrating fluid on the plug and give it a heavy treatment several times over a few days. Also give the nuts on the Tee bolts holding the two straps to the frame or body a good dosing of the fluid.

When you actually start to remove the plug use something like a large pair of vise grips or a large channel lock plier to hold the bung tight to the tank so it cannot rotate as you try to remove the plug with another wrench. The bung is tapered and it is not an easy thing to grip but do what you can to prevent any movement. If the bung does rotate there is every chance a leak will develop and that leak will be almost impossible to seal again without taking the tank to someone and have the bung brazed or otherwise secured again. Some have tried sealants between the bung and tank metal but the track record on those have not been very successful long term.

Once the fuel is drained, disconnect the fuel line. You also need to disconnect a short rubber hose that is connecting two parts of the vent tube. It is above the frame rail and if stuck to the vent tubes may even need to be cut. After that is off the tank is free of obstructions so remove the nuts holding the straps and drop the tank enough to disconnect the sender wire. The tank should be ready to come out. It is bulky and a bit heavy and awkward.

Unless you are an absolute stickler for stock, once the tank is out it might not be a bad idea to cut a hole in the trunk floor to avoid the hassle if there is a need for another new sender or some other problem develops. If you still have the thin trunk floor mat, once the hole is covered with a plate and mat over it the modification will barely be noticed.

If you do want to cut a hole here are dimensions Ross provided to show where the hole needs to be.

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When I replaced my sending unit, I successfully siphoned out most of the gas. I didn't get it all but the tank was manageable when I dropped it and no gas spilled. I put a small floor jack under the tank to let it down easy.

The advantage of taking out the tank is that you can clean it. A consideration if this tank has never been taken off the car.

Thank you Owen, Howard, Mr. Potato Head and John! I'm on it. I like the idea of cutting a hole. Stay tuned. TC

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Tough time explaining the color sometimes.....then a history lesson on 1950's McCarthy's Second Red Scare and Lavender Scare....

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thoughts are welcome, I'm diving in...cold no spark metal panel saw..... no grinder

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The 2x gas tank sending units I have, the stainless and brass Kanter $140 vs the dubious Spectra for $86. Going with the Kanter...

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Quote:
You didn't say if you are dropping the tank before cutting the hole but if you are going to cut the hole with the tank still mounted then all I can suggest is be extremely careful.

Choice of cutting tool is limited since there is not enough room between the floor and tank top to use a jigsaw. Almost limits you to a cut off wheel and those make sparks. To me, sparks so close to the tank do not sound like the best combination but that may just be my paranoia surfacing and the cut off wheel is what Ross used. I don't recall if he mentioned dropping the tank first or what other precautions he might have taken.

It might not be a bad idea to see if you can slide something like a piece of sheetmetal between the top of tank and floor just to give a bit of warning or extra protection in case the cuts go a bit deeper than intended.