fuel gauge

John Royark JR

PCS Member
I put gas in the 49 for the first time this weekend since its new gas tank and sending unit install.
The car has been changed to 12 volt and new gauges installed before I got it, and the gauge always worked, but I figured might as well just go new with the new tank (and yes it is compatible with the gauge, even same company).
Anyway, before even putting it in the tank I tested it using the cars wiring and gauge and it worked perfectly. Now after putting gas in it nothing, it stayed at empty. I even tried to tighten the ground some more and ended up stripping the screw (my luck of course), and I tried to run a jumper ground to see what happened. Nothing. I stuck the ground jumper on the positive ant it jumped to full, so know its getting juice. I was so mad it took everything I had not to take a sledge to the car.
Any ideas what is going on? I don't want to drop the tank again, so don't even know how Im going to fix the stripped screw yet so it don't leak. The car is getting very close to loosing its happy home!
 
nothing more frustrating then a poor ground to fix. or the opposite as in this case, you have to good a ground. if you take the positive wire off does the gauge go to full? put it back on it goes to empty? the gauge is working your sending unit is grounding out. or your positive wire is grounding out before it goes threw the sending unit. one loose strand is all it takes. you could have tugged the wire at the clip and cut threw the isolation . if that positive wire gets grounded anywhere it will read empty. you take it off the post of the sending unit and it goes to full then. touch the unit it goes to empty you having trouble with the unit. that is of course assuming you have enough gas in the tank to raise the float?
 
nothing more frustrating then a poor ground to fix. or the opposite as in this case, you have to good a ground. if you take the positive wire off does the gauge go to full? put it back on it goes to empty? the gauge is working your sending unit is grounding out. or your positive wire is grounding out before it goes threw the sending unit. one loose strand is all it takes. you could have tugged the wire at the clip and cut threw the isolation . if that positive wire gets grounded anywhere it will read empty. you take it off the post of the sending unit and it goes to full then. touch the unit it goes to empty you having trouble with the unit. that is of course assuming you have enough gas in the tank to raise the float?

Thanks, I will take off the positive and see what happens when I calm down enough. Right now I don't even want to see the car. Its got plenty of gas, full tank. It started leaking some when I stripped the bolt. Its just strange it worked 5 minutes before I put it into the tank and installed it. Hooked the wires up after tank was in, so I know nothing is pinched or pulled.
If the positive wire would make it read empty if grounded, why does it go to full when I take a jumper from ground and touch the positive? Wouldn't that ground it out?

That's what I get for trying to do it myself.
 
John


Once you get it all straightened out, everything will be groovy man !

You gotta relax and not let it get to you.

There are lots of things out there that are worth getting mad about, but not your '49 !

Count to ten before picking up the hammer.

Ed will help with that little issue. No doubt it will be simple in the end.


:thumbsup:
Darren
 
John


Once you get it all straightened out, everything will be groovy man !

You gotta relax and not let it get to you.

There are lots of things out there that are worth getting mad about, but not your '49 !

Count to ten before picking up the hammer.

Ed will help with that little issue. No doubt it will be simple in the end.


:thumbsup:
Darren

Don't worry, im smarter in my older years and knew when to back away and not look at it for a few days. Ive trashed way too many nice cars in my younger years because of temper (but never a pro car, except a few windows, but that was years ago).
Im still threatening to sell it though. I HATE working on cars, it was so much easier when I just paid someone to fix them.
 
you hooked up backwards? test light check. if your that full that it dribbled out the hole when you took the screw out the float may be going past the resisters and grounding out. I'm taking it that it's aftermarket float? or I'm thinking backwards on the way the resisters work but if you take it off and it goes to full you'll know I'm thinking backwards. one other trick is to get the jumper cables out and clamp one end to the lip of the tank and the other to a good ground. if it starts working you know you have a poor ground. that could be at either end of the ground strap in in the middle also. you get to wiggling the wires around all kinds of things happen. but it worked during your test so you know the sender did work.
 
you hooked up backwards? test light check. if your that full that it dribbled out the hole when you took the screw out the float may be going past the resisters and grounding out. I'm taking it that it's aftermarket float? or I'm thinking backwards on the way the resisters work but if you take it off and it goes to full you'll know I'm thinking backwards. one other trick is to get the jumper cables out and clamp one end to the lip of the tank and the other to a good ground. if it starts working you know you have a poor ground. that could be at either end of the ground strap in in the middle also. you get to wiggling the wires around all kinds of things happen. but it worked during your test so you know the sender did work.

I hooked it up exactly how the instructions said, which was exactly how the old float was (exact same float model number that was in there before). It is hooked up the same way now as it was when I tested it before putting it in, so know it is not backwards. The wires were hardly moved from the test to the install, there is plenty of room to see everything, and its not pinching or touching anything different than it was when it worked. When I was doing the jumper to see if it worked, I had one end to a good ground, and the other on the sender where the ground is now and tried other parts of the sender, and also tried it on the tank lip. Nothing. The only time it moved is when I touched the jumper ground directly to the positive wire, then it went to full. Also I know it has nothing to do with it being full, because I wanted to know where the gauge read at every 5 gallons, so when I put gas in I stopped pumping at 5 gallons, checked, and did it every 5 gallons until it was full. It read empty the whole time. I should have stopped at a half a tank when it was not reading, but I said screw it and filled it the rest of the way. Guess I thought it would start working.
I will have to see what happens if I remove the positive from the sender like you said when I can stand to see the sight of the car again, and will let you know what happens. Thanks for all the help and ideas so far.
 
you just answered your question. you run a good ground to the hot post and the gauge goes to full. I'm betting you have insulated the sending unit from the tank. the test you did shows it has a good ground on the frame. and power to the unit touch. the ground wire to new bare spot see if it moves. then use a set of star washers one under and one above the eyelet use a different screw to hold it to the tank put a drop of red locktite on the striped out one and tighten it as much as you can. as luck would have it you may have picked the only rusty hole to put the ground wire to.
 
you just answered your question. you run a good ground to the hot post and the gauge goes to full. I'm betting you have insulated the sending unit from the tank. the test you did shows it has a good ground on the frame. and power to the unit touch. the ground wire to new bare spot see if it moves. then use a set of star washers one under and one above the eyelet use a different screw to hold it to the tank put a drop of red locktite on the striped out one and tighten it as much as you can. as luck would have it you may have picked the only rusty hole to put the ground wire to.

Not quite understanding this comment. When I did the jumper ground test (one end to bare metal on the frame, the other I touched it to every screw that holds in the sender, various spots on the sender surfaces, and various spots on the tank so I know it cant be an issue with just that screw and hole the ground is attached. None of the holes or bolts are rusty, its all brand new. Im starting to wonder if all the screw threads have sealer on them so its not making contact, but when I ran the jumper and touched it to any spot on the sender (just like I did before it was even in the tank) it would make the ground so it should have at least worked doing that.
I may give you a call later to see if one of us is not understanding the other in trying to explain it in type.
 
Last edited:
hook it up as it should be (like the old one was) and drive the car around a bit. if it's the sending unit then, when you drive it it may come and go. the float could have pulled the wiper away from the resister. that would great the open problem and the gauge would not read.

last is it a 6 or 12 volt sending unit? if it's 6 the unit may just have burnt out. I understand it's been converted to 12 and been that way. they use the resister on the gauges to drop the voltage to them. but the sender is on a different circuit normally one would get a 12 volt sender. or at least that's how we did it in the jeeps I converted.
 
hook it up as it should be (like the old one was) and drive the car around a bit. if it's the sending unit then, when you drive it it may come and go. the float could have pulled the wiper away from the resister. that would great the open problem and the gauge would not read.

last is it a 6 or 12 volt sending unit? if it's 6 the unit may just have burnt out. I understand it's been converted to 12 and been that way. they use the resister on the gauges to drop the voltage to them. but the sender is on a different circuit normally one would get a 12 volt sender. or at least that's how we did it in the jeeps I converted.

As I stated before, it is hooked up as it should be, which is exactly how the other one has been hooked up for the last 20+ years, and it worked fine the whole time. (its also hooked up exactly the same way as it was when I tested it before I put it in the tank, and it worked)
Yes it is 12 volt, the car was converted and completely rewired when the sender I took out was installed along with the new instrument cluster. The new sending unit is the exact same part number and brand as the one I took out, and it is the same brand as the gauge. Everything is the same as it has been for at least the last 20 years (except the new sender and tank, which is the same correct tank).
I have drove it around, about 20 miles or so, after it was filled, pretty much from the gas station home. I thought it may be stuck for some reason, even though I know it shouldn't be, that's why I decided to fill it anyway even though it was not going up at every 5 gallon mark when I checked it.
No way the float could make the arm pull away from the resistor, its in a plastic holder that is riveted together, the only movement it can do is up and down.
I know the issue has got to be something minor, but I still cant bring myself to mess with it yet. I looked at the car yesterday, and started getting worked up as soon as I saw it, so need to give it more time.
I know you are trying to help and I really appreciate it, Im just irritated at the car and myself because its not working, and Ive tried everything mentioned so far (except removing the positive to see what happens).
 
Last edited:
from the way your talking it sounds like a bad sending unit. they either go out right away or they last a long time. if you unhook your hot wire you can test it with a Ohm meeter. with gas in the tank there should be resistance reading. if there is none the unit went out on you. and everything else is good. if it reads resistance them you need to start looking else were.
 
from the way your talking it sounds like a bad sending unit. they either go out right away or they last a long time. if you unhook your hot wire you can test it with a Ohm meeter. with gas in the tank there should be resistance reading. if there is none the unit went out on you. and everything else is good. if it reads resistance them you need to start looking else were.

I really hope its not the sender. That will really **** me off if it only worked long enough to make sure it worked. I knew I should have never touched it.
Again, thanks for the help.
 
When it was converted, did you keep the positive ground? Do you have a fuse in line to the gage? My 49 Kaiser when reversed, everything went opposite, full is empty and so on just asking.
 
When it was converted, did you keep the positive ground? Do you have a fuse in line to the gage? My 49 Kaiser when reversed, everything went opposite, full is empty and so on just asking.

It is EXACTLY how it has been ran since it has been for 20+ years. The only thing that has changed is installation of a new gas tank and sending unit, which is the same model that was in it.
I haven't messed with it anymore, I figured it would just get my heart rate up and I would end up hating the car (I was already very close to selling it) so I figured I would just go by mileage. I took it on a long trip and have ran 4 tanks of gas through it since. I filled it agan and parked it in the garage. I took it out yesterday and now it went to full, like it should be, so I guess we will see what happens.
Thanks for everyones help.
 
Poor ground, when you get the ambition just run another one. The old one may be broken in the middle under the insulate. It either hooked up again or the tank shifts and ground it's self
 
Still not sure how it can be a bad ground, when everything worked fine until the tank was installed. Besides, remember I tried running a new ground and it didn't help. Its going to be how it is for quite a while, not sure if I will ever feel like messing with it again. Thanks for all your help in trying to solve the problem.
 
an internment open on either side of the circuit is a vary hard thing to trace out. it might not be at the tank even. shorts are easy all you have to do is look for the smoke.
 
Back
Top