51 Hornet

hudsonsplasher1

Hi Guys;

Looking for some help with the gas gauge. I have been helping my neighbor with his 51 Hornet. It has a new sending unit, and I know the dash gauge works. we have hooked up the sending unit( out of the tank)to the wire leading to the gauge, and it works. But when we put every thing together, put the tank back on the car with a ground wire to the body, with gas added, it doesn't work. We both just stand there scratching our heads. Any ideas would be much appreciated. Thanks.

464Saloon

It may sound silly, but how much gas do you have in the tank? When you were testing it out of the car, how far did you have to move it to get a reading on the gauge? I have seen the rheostats kind of flakey on these things, especially on aftermarket units, then I would double check your grounds, they can be deceiving too. I had a similar problem with grounds on dim headlights. The grounds were there and tight, but i took everything apart and cleaned the connections and reattached then Wallah! bright headlights.

Unknown

Make sure that your sending unit float doesn't have a hole in it. If it takes in the gas and sinks it will always read empty.

[Deleted User]

If the tank has been sloshed the float may be sticking to the bottom of the tank, put a little petroleum jelly (vaseline) on the bottom of the float, otherwise I think I can talk you through a diagnosis without the use of any analysis equipment>

1-the tank sending unit and the fuel gauge must be grounded, run a black wire from the sending unit and the gauge to the NEGATIVE battery post and clamp it with a pair of vise grips.

2-run a red wire to the +post on the gauge and the POSITIVE battery post and clamp it to the battery post>

3- run another wire (any color except black or red) from the gauge sender side to the sender unit (the reason for the different colored wires is to avoid confusion as to what wire goes to each component)

4-don't overlook a bad crimp connection on the existing wires (I've seen crimp connectors crimped on the insulation wit no connection to the copper wire in addition I've seen them crimped so hard that the crimp breaks the wire.) the best way is to remove the plastic insulation from the connector, then crimp so you can look at it/solder the connector and use heat shrink tubing over the solder joint for insulation.

5-one last thought, scrape the area that you are connecting to so that you have bright shiny metal for your connection.

6-start removing the added wire circuit one wire at a time and test it, I'd start with the grounds as I suspect that is the problem.

GOOD LUCK,

bill j. harris

Park_W

For a quick check of everything but the sender and its ground connection: with everything hooked up and ignition on, use a jumper wire to ground the terminal on the sender. If the gauge swings over to full, everything from sender forward is OK.



If the gauge did move OK, then jump the sender terminal to the sender mount flange. If the gauge moves up then, your "new" sender is bad.

Unknown

a problem lI lhad silmiliar, is if the float lis linstalled with long side offset. it can rub on the center baffle in the tank and not sork up or down freeley after bein screwed down. check clearance of end of float to center baffle. good luck, BILL ALBRIGHT

[Deleted User]

I had the same problem when I put the sender back in my 54, after having the tank cleaned and sealed. Worked before but not after I put it back in. I had cut the gas line to install an electric pump but had not yet put the pump in the line so I used a short piece of rubber hose as a splice. The tank itself, was not grounded, and the sender was grounding through the fuel line. So the rubber line acted as an insulator. I had to run a ground wire from one of the screws that held the sender in, to the body. Gauge works fine now...Just what worked for me.

Bob Hickson

Unknown

hi, this is hudsonsplasher neighbor with the gauge problem. thanks to all you sent your input. i tryed all of that plus more. i have it out again and i checked the resistence from empty to full and it reads 120 ohms empty to 20 ohms full., does anyone know what it is suppose to read for sure?

littlerunt

Park_W

To my recollection those figures aren't exactly what they typically read, but ought to be close enough to work at least somewhat normally. I think they typically run from very low (0-5) to a high of about 70. Anyone confirm that?



What happens when you ground the tank unit wire right there at the tank ... does the gauge swing pretty rapidly toward full?

Geoff

The ohms readings are near enough to get the gauge working. In regards to Bills advice, remember that these cars are POSITIVE GROUND, so if you are hooking up jumper wires according to the advice given you are going to get short circuits and will set things on fire! The ground polarity doesn't affect the way the gauge works, they will work either way round.

Geoff.

Unknown

Hi, it's me again. i ran direct wires to the gauge and sending unit and yes the polairty is right. If you connect the two wires together it regesters full. i put a "reostat" in place of the unit and i can adjust the gauge on the dash and move it from E to F . It has to be something simple but i can't figure it out. thanks again for all the help, if we ever get it figure out i'll let you all know. i don't want to pull it again. Will.

Unknown

Hi guys, this is splashers neighbor with the gas gage problem. WEll, Park W hit it right on the head. The correct ohms reading should be 10 to 70 ohms. The unit that was in had to be wrong even though it was new. I called Ken Amman and he didn"t have one so he told me to call Glen Johnson in Utah. I did and he had one. To make along story short it works just like it is suppose to. I put 5 gallons in and read 1/4 10 gallons and it read 1/2 . I hope I don't have to pull it out again! Thanks again to all who added their advice, which was all good also, and thanks to Gene better known as Hudsonsplasher for getting me into this. Thanks Will.