Gas gauge woes..

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Ruger64

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I installed my new gas tank. Okay...I used my new float sender...which I already had in my old tank that worked fine. I put my new tank in today...with the float that worked. Grounded the wire from the sender tube to the fuel line. Kind of jumping over the rubber hose connection. Now my gas gauge is not working. I know its not the gauge. What happened? Any advise?....1971 plymouth valiant...slant 6.....
 
Ground the sender line, turn on the key. You should get a full reading in a VERY short time. Don't leave it on longer than to test. Can you tell if the temp gauge is working?
 
67Dart273 said:
Ground the sender line, turn on the key. You should get a full reading in a VERY short time. Don't leave it on longer than to test. Can you tell if the temp gauge is working?
Click to expand...

Temp and amp gauge work perfect. The gas gauge did until I reinstalled the new tank. And I usd the same sender that was brand new that worked before I took it out. . So the wire that goes on the sender.."snaps onto it" ...ground it for a short period. And see if the gauge climbs? If it does?
 
ironracer1 said:
If it does, the problem is not between the gauge and the wire.
Click to expand...

It worked fine. I only changed my tank. This is frustrating. So if it works...as in the gauge goes up grounding that wire. What do I check? I know my sender is good.
 
Make Sure you have a good ground at the sender, you can use a jumper to determine this. If not , ohm the sender.
 
ironracer1 said:
Make Sure you have a good ground at the sender, you can use a jumper to determine this. If not , ohm the sender.
Click to expand...

Thanks. I will make sure I have those two little clamps tight enough on the ground wire. Hope that does the trick. I am amazed. I took it apart..put the tank in...and poof...quit working...my luck.
 
Assuming you have enough fuel in the tank to register at the gauge... The sender wire has a connecter on that end that can fail just as easy as the ground jumper can fail.
All connections must be good for it to work.
 
I replaced my old tank, sending unit, fuel line, and rubber hoses. Then I put my new tank and new sending unit in, also put in 5 gallons of gas. It didn't even register until I put in another 5 gallons. Weird... but after the initial past half tank it now works fine, Full to Empty, it even reads pretty close. Might be like mine was and need more gas in the tank to get it off the bottom.. I kinda think sending units have a sticking point when almost down to the limit of showing empty. But I did check it with an Ohm meter before the install and knew it was fine. So it only left the fact of a bad ground or bad connection at the tank. I had my guages tested and repaired before I changed the tank.. maybe this will help a little..
19..
 
After preforming the test above to see if the gauge and wire is working, get a battery jumper cable and clamp one side to the fuel tank along the seam. Make certain it is a good connection. Clamp the other side to a good ground. If THAT makes the gauge work, then your fuel tank ground is not good enough.
If that's the case, sometimes a copper wire and two hose clamps on the fuel line works better than the factory "clip" ground.
 
You can also clean the clips on that factory jumper, and the areas on the sender and metal fuel line with sandpaper or steel wool. Check that the clips are snug and if not squeeze them in a little. Use fingers, not vise grips. Is the wire in the factory jumper broken?? Small hose clamps and copper wire to replace the factory jumper also work. spread a little grease where the jumper (factory or homemade) attach to the sender and fuel line.

ATB

BC
 
I dont have the factory clip thing. I use two small hose clamps and a copper wire. Thats the way I did it before and worked fine. I didnt get a chance to go in the garage today. I put exactly 7 gallons of fuel in it. It holds 16. I even pulled on tge copper wires. The clamps are holding the wire ends really tight. I guess I will take them off and maybe inspect them. My fuel line is even new. I am lost.
 
Ruger64 said:
I dont have the factory clip thing. I use two small hose clamps and a copper wire. Thats the way I did it before and worked fine. I didnt get a chance to go in the garage today. I put exactly 7 gallons of fuel in it. It holds 16. I even pulled on tge copper wires. The clamps are holding the wire ends really tight. I guess I will take them off and maybe inspect them. My fuel line is even new. I am lost.
Click to expand...

It's not at all clear to me what you have actually checked?

Did you ground the sender wire, or not, and what happened?

If the gauge deflects to full with the sender wire grounded, then the gauge/ wiring is most problably OK.

As Red said, check the sender connector. The wire can break right there in the connector.

If that checks out, take your meter and measure the resistance/ continuity of the tank sender. Check resistance/ continuity from the sender supply tube to body ground.

Approximate sender resistances are:

L = 73.7 Ohms (empty)
M = 23.0 Ohms (1/2)
H = 10.2 Ohms (full)
 
OK you said "the fuel line is new". The original fuel line was fastened to the frame rail with several little steel clips. Those clips chassis grounded the fuel line. If you have changed the manner in which the fuel line is installed you may need to ground your sender to the chassis in another way/place.
 
i have found most of the time it is the ground if you clean up the ground connection and use some dielectric grease this will help. the next is make sure that the one is grounded to the body. i have a meter that checks continuity threw the lines you my want to get one and check the continuity
 
Is the float stuck in the tank??? Pull out the sender and have your wife watch the gauge with the key on and you sliding the sender's float up and down. If it now works, the float was either flooded or stuck.

Good luck!
 
I will check all these things tomorrow. I got company today and could not go in the garage. I will say I never knew there was a body ground????? Are there two grounds?
I only know about the ground that goes from the sender to the fuel line. Are there two grounds?
The original line was left on. I cut some of it off when I replaced the gas tank. It was pressing against the new line. I am starting to wonder if that old line I cut off was grounding the new one since it was pushing against it.
 
The thing is the battery is (or at least should be) at body ground

The TANK and the sender may not be. You are talking about a tank, subject to rust, with a sender, the compression ring, sender, and tank flange all subject to rust, and even the fuel tube--which was what the sender was originally jumpered to with the little clip, is "not" really grounded to the body!!!!

So when I say check sender tube to body ground, you are checking whether the sender is actually grounded.
 
We could just remove the ground question... With a piece of wire attached to the senders tube, put a ring terminal on the other end of that wire, use a drill point hex head screw to attach it to the frame member pretty much right between the shock mounts and tank straps.
The factories little jumper clip was their typical cheap, quick assembly, way of doing things but chassis ground is available all around and there are better ways to get it.
 
Okay, I finally got time to work on my car.
Well, I did figure some things out.
Okay, My 1971 Valiant had a 1969 Dart tank in it, when I got it.
Okay, now that tank "dart" is a 18 gallon, and my "right tank for my car" is a 16 gallon tank. I put it in!!
Confused though, their the same dimensions, but one is more gallons? Anyhow..
I put my new sending unit in that I ordered on ebay. It is a "cheapo" one. That may have been my mistake right there.
The one that came out of my car, "remember it had a dart tank in it" had a sending unit in it, that was longer by about 2 inches. The float and pick up. But I figured it was longer to being in a dart tank?
I checked my ground today. Was fine!
I currently have exactly 7 gallons in the car...16 gallon tank.
I then pulled my filler neck out, and reached in with a long metal rod, and lifted up on the float, and my son yelled out that the gas gauge was going up. I lifted the float the whole way up, she went to full.
Okay, I then stuck the tank, and it measured 4 inches on the stick. The tank is about 9 1/2 inches. Tried to measure while it was in the car.
Right now it only shows about a titch above "e", when it should be right below a half a tank.
Do I just have a bad sender/float? As in the wrong one/Length? It does function, when I reach in the tank and move it manually.
 
I have seen a lot of this due to shorter pickups fill your tank itll say full but drop really fast and youll still have the extra in after it hits e so either get the correct length or remember what you really have in it lol it sucks a lot of after market ones are too short
 
huge difference but both say they are for a 72 duster v8 car lol
 

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