VCCA Home Forums TECHNICAL - 1945 AND EARLIER 1933-1936 35 Master Gas Sending Unit

I've taken the Gas Tank off my 35 Master. I took the sending unit out and it looks good. I know my Gas Guage is not accurate. Is there any way to test the unit while out of the Tank? Does it have to be grounded and if it tests OK will it then work once back in the Tank?

You can test the sending unit with an Ohm meter. The meter needle should move up and down as the sending unit arm is moved up and down.

Must put one lead of the ohm meter on a non-painted or not rusted part of the sending unit flange area that grounds to the tank. (The ground is through the bolts that hold the sending unit to the tank. [A gasket is used to prevent leaking gas] The tank is grounded through the straps that hold it to the car. The ground circuit is completed back to the battery via other items on the car. Also, the gas gauge in the dash must be grounded to the dash for it to work. Sometimes repainted dash prevents a good ground in that area.) The other lead onto the terminal of the sending unit where the wire hooks to that goes to the gas gauge in the dash.

I have tested the Unit with an Ohm meter and it works. I know the Gauge works. I also know the Corks on the Float work and Float in liquid. What I don't know is how to test and make sure it's accurate before I put it back in the tank and put the tank back in.

It now looks like the Gauge is working and by moving the Float on the Sending Unit I can get the Gauge to move. The problem is the Gauge only shows about 3/4 full or 3/4 empty, not Full or Empty. Can I put a resistor in the line to correct this problem?

Actually that is not correct. It goes to Full but only down to 1/4 when it should read empty.

Current passes from ammeter to the ignition switch and then to the dash unit top terminal. The current now passes through the "Choke or Limiting Coil" to the common connection between the two coils, which is the lower terminal on the dash unit. HAVE YOU CHECKED THE CHOKE OR LIMITING COIL? With the whole system hooked up.....You will have to "read" the increase in voltage between 1/16th to 1/10th of an ampere! As you move the cork tank leaver. Most meters do not read that fine. I would carry this to a Repair Shop where they have a meter that can read this. Otherwise replace the "Choke or Limiting Coil" This appears to be a folded piece of paper between the terminal under the dash. It may possible be the trouble if the brass on the "Choke or Limiting Coil" is corroded. Or it could be you do not have a good ground at the dash unit or the gas tank end. The sending unit at the tank end is cadmium plated rheostat or resistance coil, chromel wire on a celeron core with BRASS parts. Could have a flake of dirt or crud on the sending unit coil end. (Note: The sending unit can not be taken apart.) To prove it is not a grounding problem ....run two wires...One from dash unit and one from sending unit to the same good ground.

Thanks for the info. I'll have to read it about six times for it to sink in.

hello terrill.i have done a full rewire on my 35 standard holden body chev...every thing is working now,but last thing to finish is the fuel guage ..so i was doing a search bout it and found this thread...pictures of the "CHOKE OR LIMITING COIL?"
that ive got behind my gauge...the card piece??


....do i need a new one[obvious??]and where to get one ...in australia ??...thanks ...dave

Dave
I think that piece is only fitted to help prevent the 2 wires connecting (shorting) at the guage as all I have seen are only cardboard.
Tony

That piece is a non conducting fiber. I wouldn't use plain cardboard as it could have contaminants that could pass electrons or become damp in humid weather.

Not familiar with a supply place in Australia, But might try to re-use the one you have until you find one. I would run a wire from the back of the dash gas gauge (where it connects to ground) to the body (good ground). Also, the gas tank where the unit bolts to the tank, to the good ground. "Ground path" on these old girls can get tricky. It is the "ground path" that gets messed up and causes the problem most of the time not the "Hot" path.

J Franklin could be right with the non conductive fibre as I have not taken much notice of the actual material,
Terrill is right the "complete circuit" needs to be good for it all to work correctly not only the "supply" (depending on which way you believe the elctrons flow (I wont argue with you Ray but I know there is a difference)).
Tony

happy..just repaired my fuel guage with solder,white tape and two drops of araldite...wont know bout accuracy till later..
but looks rite...huzzah..thanks for the help guys...dave..

For positive grounding I like to use star washers where needed because they dig in to good clean metal when tightened up. Good luck with your project & keep us informed.

yes..on a terminal i use a flat washer then a star washer on top of that...wont move...i should have taken pics....

Hurrah!!! Way to go Dave....good luck on it.