The Stovebolt Site Forums The Parking Lot '60-'66 Trucks Gas Gauge issues

I'm having trouble with my gas gauge. It reads just Empty or just above all the time. I've replaced the sending unit in the tank a couple times. After the new one is installed, it will work for a while, but eventually will quit working. (It is the original tank behind the seat.) Any suggestions on what might be the issue and what I could do to fix it?

Hello Mike, it may help to really, really clean the ground wire bolting point at the tank. Must be bare metal and all the terminals must be bare metal and the wire not broken.
Then be sure your gauge frame is grounded to dash. It's usually just the ground path that is intermittent. To test this theory, Remove sender, run a test wire from battery ground post to the sender flange grounding tab/wire. Just run it thru the cab window. Direct to sender. Keep the sender gauge wire connected to sender and see if the gauge starts working. You can move the float up and down by hand and watch gauge. Key on. Report progress.

I assume you have the ground wire between the sender flange tab and the cab sheet metal? Usually this wire is already welded to flange on 60-66 sender....or there may be a tab for a spade terminal. The wire must be screwed to a bright bare metal spot on cab metal. No paint, no rust, no corrosion, no washer in between. Good tight crimped terminal if applicable.

I believe the gauge is grounded by the round brass slug on the back touching the recessed can, can screwed to back plate and cluster screwed to dash. Would not hurt to add a ground wire somewhere or test gauge ground with a direct jumper to battery. If other gauges and dash bulbs work, it would seem that you do have cluster ground. There are dozens of places to lose ground on a truck. Many of the ground paths are just screwing or bolting pieces together. If you live in a moist area, corrosion sets in.

Mike:

Do you replace the whole mechanism when you replace the sending unit?

And how long does it take to stop working?

Cris

If your gauge works, it's the sending unit (assuming you have good connections).

If it's the sending unit, it could be:
1. the resister in the unit, or
2. the float

If your gauge reads properly when you move your float up and down, as Bartamos outlined, it's your float. You may have a brass float and what happens is they develop a pin hole in them over time. Then they fill with fuel and your gauge reads "E". If this is the case, just replace your brass float ($6 at laps or online).

Cris, I replace the whole sending unite twice. It works for maybe 6 months.

I'm guessing it is a ground issue. I'll be looking into that first and try testing it as described above.

Thanks for the suggestions.

Mike

Mike there are several threads going in the Electrical Bay about this subject. May be of some help.

It seems like we have posts on this every day. We have covered it too many times. Even our shop sharks are not searching our vast archives.

Search works sometimes

Some of the old links are busted due to photbucket,picasa and other links being disabled

Common problem on most forums

Mike:

My guess, based on it taking months for the problem to show up and the fact it registers at or near empty, is the float is leaking. The sending units have brass floats and a very large percentage of the aftermarket floats leak. When I replaced mine, it leaked as well.

When you pull the failed sending unit out of the tank, you should be able tell if the float has leaked because there will be fluid in it.

A common fix is to remove the brass float (it simply snaps in place) and replace it with a plastic float. This is such a common problem that someone has identified a suitable replacement, I believe it is a Ford part. I may have the part number at home, but a Google of the problem usually pulls it up.

I finally got this fixed. I purchased a float that has this description. "These floats have the brass holder and light weight polyurethane body." I found it on eBay and it was less than $20. When you shook the old float you could hear gas inside it. The new float was installed and the gas gauge works as it should. So excited. I have a drive coming in a couple weeks of 200 miles and will be so glad to have a gas gauge that works.

Thanks for getting back with us. Glad it all worked out.

Ok new float, and new sending unit, cleaned all grounds, bare and new bolts, I have filled tank to 10 gallons, and it still reads, almost empty, so now if i fill it to full and it reads the same, so now what ?

Some of the test procedures are for guys with older parts that want to know what's wrong. The procedure for new parts is to test and calibrate them together on the bench before installing. You can pull them and do that to be sure the new gauge and sender are good or try to test in vehicle. Test not guess, as Jerry would say.


From the web:
If your gauge reads FULL AT ALL TIMES:

A. Probable Causes
1. Wire from dash gauge to sending unit is broken and/or the connection is corroded (not making a good electrical connection).


2. Resistance wire inside sending unit is broken


3. Sending unit is not properly grounded to tank or tank is not properly grounded to chassis

B. Testing
1.Remove the wire from the contact stud on the sending unit and ground it to the chassis. If the gauge now reads Empty, the trouble is either poor grounding of the sender or a bad sending unit.


2.If the gauge still reads Full, touch a grounded test wire to the sending unit terminal on the back of the dash gauge. This terminal is often marked with a red tag. If the gauge now reads Empty, the wire from the dash to the sending unit is broken or the connection to the dash gauge is corroded.


3.With the sender removed from the tank, connect an ohm meter to the sending unit (one lead to the contact stud and one to the housing) and check the resistance of the sender as you manually raise and lower the arm. This reading should be 0 to 30 ohms (or very close).


4.If none of these tests finds the problem, the dash gauge is the problem and should be rebuilt or replaced.

C. Repairs
1. Make sure that a good ground is present at the dash gauge and also at the sending unit. Run a separate ground wire to the chassis if necessary.


2.Sliding contact arm may not make good contact to the resistance wire windings in sender. If you are experienced with electrical repairs you may be able to clean the wiper and resistance wire coil or replace the wire. Otherwise send the unit to a specialist or replace the unit.


3.Check for good ground at sender body and gas tank.