240Z/240K Fuel Guage reading incorrectly

[Bambikiller240]

Thanks for the info. My Fuel gauge has been screwy for over a year, just like you describe. Guess I have to try to find a gauge that works properly.

[Marty Rogan]

ez73,

I agree with Carl. Check your vent lines, as this is a very common problem.

There are 4 cables that are attched to the heater panel slider rods. Follow them to the ends where they connect to the various vents. There are phillips head screws that hold the wires in place. Loosen the screws and the wire will pull out of its slot. Then when you remove the 4 face plate mounting screws, you can move it forward out of the way.

Does anyone know what that "contact point" is that Daniel described? The guage on my 71 drifts like he described, and I can't trust the accuracy at all. So, from this discussion, it sounds like the guage may be flakey. I wonder if it would do any good to take it out and clean it, or just replace it?

Marty

[Zedrally]

The 240's down here [Oz] didn't come with all the fancy plumbing, which in a fashion is a relief. So that solution is applicable to all zeds[not that that was implied].

The gauges in zeds work via some type of heat transfer. There is a coil that heats up a metal strip which then expands and moves the indicator via a system of levers and pinion gears. [if memory serves me correct, if I'm wrong discard this as rantings of an old fella].

This would be one good reason NOT to solder the contact mentioned by Daniel.

Cleaning the gap would be a good place to start, I just learned to live with it.

I don't suppose there are any Instrument Repairs on the list are there?

MOM

[Daniel]

Zedrally you are indeed correct about the bonding of the contact points. Mine started on the temp/oil guage both would sway in tandem Like I had a power problem. I cleaned , tested, ohmed, jumpered.... Amigo I KNOW electrics. I thought I had it , then no..The guage(s) with the face removed revealed a contact set that was shared between both gauges. I tried burnishing (ultra fine file) the contacts to no success. After a trail of failure, I found solder to be the only fix. They work correct. I then assumed that the contact was to ease assembly and not required. Of course I did note the wire windings as like an electromagnet. The fuel guage doesnt play solder fix. The temp/oil pres. share.The fuel is on its own contact. I dont know what or if that means a thing.

[obxtrainman]

So does the tank need to be grounded or not? I put a new unit into a tank the prior owner had exchanged. He had put in the original unit. At full, the gage read just over half. When I filled it up, it would only take about 7 gallons. I put some leads on the (TWO) wires that go to the sending unit. With the new unit in my hands, I could watch the gage go full spectrum. Empty to full. I put the new one in,,,,same problem. I took it out again, looked inside,,see nothing for it to hang up on. I have now measured the old unit thoroughly, but haven't had a chance to measure the tank yet.

There are two wires coming out of the same harness as the two sending unit wires. They are butt connected together. It looks as though they had been painted green at some point. I guess I'm asking if they might be a ground for the tank, and should I affix one to the tank. Thanx in advance for any responses.