Topic: Gas gauge 1936


Ron3181    -- 12-31-2019 @ 1:28 PM
  Forum members helped me with my sending unit. Everybody said to replace the float which i did and the gauge worked great. I took the car out today (up and down hills) and noticed when I stopped and the motor was at idle the gauge would drop to about 1/2. when I stared moving the gauge would go back to full and stay there. The tank was full. Is this right or should the gauge not drop? Thanks again for all the help.


JayChicago    -- 12-31-2019 @ 4:25 PM
  Here's a guess. More experienced members may have better ideas.

If tank is full, seems sloshing of the fuel / float position should not be that much different stopped vs. moving. But electrical system is different with engine idling vs. moving. I'm stretching here, but maybe it's enough different to explain this??

At idle, only battery voltage available. Is the battery weak?
OR
When moving, generator will be putting around 7 volts into the electrical system. Maybe this is enough to overcome some resistance, like a poor connection at the sender. The most likely poor connection is the ground path between sender and tank. You could try a temporary ground wire from the sender body to a good ground. If that changes things, you've identified the problem.


trjford8    -- 12-31-2019 @ 4:50 PM
  Make sure all wire connections are tight at the gauge and the sending unit.


MG    -- 12-31-2019 @ 5:23 PM
  Its is my experience that some gas gauge fluctuation you are experiencing is normal.

What did you end up with as a new float?

This message was edited by MG on 1-1-20 @ 10:24 AM


Ron3181    -- 01-01-2020 @ 6:19 AM
  I ordered A float from Dennis Carpenter V8 parts and I am waiting for it to arrive. I went to my local parts store with the old cork float in hand and asked them if they had one like this. They did have an all plastic float the same size as my cork. They said they had ordered it for a customer and that person did not take it. They could not tell me where they got it from. It was a plastic float for a sending unit and it fit right on my rod hook. It seemed to work great at first but when I took the car out is when I noticed the gauge droping at idle.


trjford8    -- 01-01-2020 @ 7:29 AM
  What is your amp gauge doing at idle?


TomO    -- 01-01-2020 @ 8:26 AM
  I would check to make sure that there is 6 volts at the wire on the sending unit, with the engine running at idle in your driveway. If you have 5.5V or less, check your battery and connections at the gauges.

If the voltage at the sending unit is good, take a jumper wire and connect one end to a screw holding the sending unit in place and the other end to the body floor. If you have a bad ground, the gauge will now read the tank level.

In your other post, you said "I cleaned the inside real good with contact cleaner, put everything back together and still the gauge would only show 1/4 or less. "

Did you mean that you cleaned the inside of the sending unit by prying off the cover and spraying contact cleaner inside area shown in the photo?

You can do an electrical test of the sending unit by disconnecting the wire from the sending unit, remove the unit from the tank and connect an ohm meter, on the X1 scale, between the terminal and the case. Move the arm slowly through the range of movement while watching the ohm meter. The needle on the meter may fluctuate as the arm is moved but should indicate 0 ohms through the movement. If you get a high reading, you will have to clean the contacts inside the unit. Be careful of the hair like wires inside the unit, they break easily.

Tom

This message was edited by TomO on 1-1-20 @ 8:35 AM


Ron3181    -- 01-01-2020 @ 8:57 AM
  amp reading at idle is +2 at best


MG    -- 01-01-2020 @ 10:23 AM
  Ron3181 said >"It was a plastic float for a sending unit and it fit right on my rod hook."??? The '36 had a 'hooked' arm on its sender??? - Unlike the '37 pictured here?> https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=4990&keywords=cork%20float

and here > https://www.earlyfordv8.org/forum/viewmessages.cfm?Forum=18&Topic=4990&srow=16&erow=30&keywords=cork%20float

No hook on the '37 sender....

This message was edited by MG on 1-1-20 @ 9:27 PM


40 Coupe    -- 01-03-2020 @ 4:31 AM
  Ford originally used the KS style as pictured in the post above. about 1939 Ford changed to the newer style. The KS has the float rod going through the center of the cork float, the newer style has a loop in the rod going around a brass float. Many of the early style have been changed out over the years. The later style will fit and electrically work in the early tank. Depending upon which of the newer style senders you find the float rod may have to be modified for length.


alanwoodieman    -- 01-03-2020 @ 8:37 AM
  run a ground wire from the sender down to the frame, doing this eliminated problem with a 36 that had some of the same issues


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