basics on tank gauge sender ?

Propane, Butane, LPG, GPL, C3H8, C4H10
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alwaysFlOoReD
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Joined: Mon Mar 29, 2010 11:00 pm

basics on tank gauge sender ?

Post by alwaysFlOoReD » Tue May 15, 2018 9:09 pm

I just bought a 1980 GMC/Grumman van with a 350ci on propane. It's running well but I don't know how much fuel is in the tank. I checked the wire from tank to dash by eyeball and see no problems. I'm going to check the dash gauge tonight by putting 12 volts to the terminal. How can I check the gauge on the tank? I went to a propane place and got a quote of C$70.00 for a new sender. I want to make sure mine is toast first. I have access to a multi-meter, both digital and analogue, and can follow simple directions.
Thanks,
Richard


BigBlockMopar
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Re: basics on tank gauge sender ?

Post by BigBlockMopar » Fri May 18, 2018 4:14 am

Usually there's a gauge on the tank.
Or mostlikely a gauge with a variable resistor incorporated.
With a multi-meter you can measure the resistance to ground.
A firm push against the car will agite the liquid propane inside and this will show on the gauge or multi-meter.
You should also be able to hear the gauge mechanical float move inside when the liquid is moving.
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C3H8
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Re: basics on tank gauge sender ?

Post by C3H8 » Fri May 18, 2018 12:36 pm

The old gauges and senders were fairly easy to check out. All GM's of this vintage OEM gauges were 0 to 90 ohms resistance. Check the dash gauge assuming it is using the OEM gauge. First by remove the signal wire from the sender at the tank. The dash gauge should read overfull. Then ground the wire. The dash gauge should move to empty. If this happens the dash gauge and wiring to the tank are fine. The mechanics of the in tank mechanism can be checked out as stated by Big block.

Propane senders came is various ohm ratings matched to the manufacturer. In the 80's GM's were 0 empty and 90 ohms full. Fords and Dodges were the reverse 70-10 ohms To check the sender remove it from the intank float assembly. It should be held in with two small Phillip head screws top and bottom. Hopefully they remove easily. They tend to corrode and then break off when removing them on older units. If they do break off a new twin site installed with a small bead of silicone can be used. The sender should be marked inside the glass and it should be 0-90 ohms. Senders came in two types, Metal bodied single pole and plastic body two wire units called Rochester twinsite. The single pole unit had a metal housing that provided grounding through the tank once it was attached to the tank. With this unit you can attach the multi meter ground to the body and the positive to the single brass terminal. You can then turn the gauge needle using a magnet to verify the sender ohm reading is right and there are no breaks in the resistance coil. With a two wire unit all plastic sender attach the leads to the wires and use the same test procedure with a magnet. If this all tests good check the ground connections. Many times the two wire unit ground is corroded. On single wire units the tank bolts fastening it to the frame can rust and prevent proper grounding. To check this attach a wire to the mounting screw and run it to a known good ground or straight to battery. If the dash gauge is faulty you will have to replace it or install an after market gauge.

alwaysFlOoReD
Posts: 17
Joined: Mon Mar 29, 2010 11:00 pm

Re: basics on tank gauge sender ?

Post by alwaysFlOoReD » Sat May 19, 2018 1:17 am

Thanks.

alwaysFlOoReD
Posts: 17
Joined: Mon Mar 29, 2010 11:00 pm

Re: basics on tank gauge sender ?

Post by alwaysFlOoReD » Sat Jun 16, 2018 5:34 pm

I'm going to admit I'm not the brightest. The problem was a 50 cent fuse.

storm
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Re: basics on tank gauge sender ?

Post by storm » Sat Jun 16, 2018 11:00 pm

These things happen, at least you got it working and let us know what the problem was.
Every job is a self-portrait of the person who did it. Autograph your work with excellence.

Fuel flow requirements calculations viewtopic.php?f=5&t=1638

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