How To Repair the Fuel Gauge Sending Unit on a Classic Chevy Truck

I'll show you how I repaired the fuel gauge sending unit on my classic Chevy truck. The fuel gauge on the truck was showing empty, even though though the tank was full. I suspected the fuel sending unit was not working. I tested the gauge by grounding out the signal wire to the fuel gauge and then used my digital multimeter to test the resistance in the circuit. When the fuel tank is full, there should be 90 ohms of resistance between the fuel sending unit signal lead and ground. When I discovered the resistance was low, I knew I had a problem with the fuel sending unit.
This is a 1970 C-10 Chevrolet pickup truck. I welcome your comments or questions! Please like and subscribe.
Here's another video featuring this truck:
• C-10 Chevy Pickup Truck
Here's my truck repair playlist:
• Truck repairs
#RepairFuelSendingUnit #AntiqueChevytruck #ClassicChevy #truckrepair #ChevyC-10 #bluecollar #prowrenching
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ABOUT ME:
Pro Wrencher is a mechanic who has experience repairing everything from old farm equipment to autos/trucks/boats to locomotives. He lives in an old house and drives old cars and has old boats- giving him a lifetime of stuff to repair!
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[@Rick-xb5kq]

Thanks for the vid my 1970 CST guage stop reading today...Like that General Electric coat....I'm a GE retiree of 31 years.

[@ProWrenching]

Thank you! I got that jacket while I was working for GE for their Transportation division- working on locomotives.

[@Rick-xb5kq]

@@ProWrenching Cool I worked in the power generation division making heavy duty gas turbines.

[@Rick-xb5kq]

Thanks again for the vid I replced mine today...may have been the original...has a heck of time getting the locker to rotate when removing the bad unit. I bought the new unit from Jegs we will see how long it last.

[@ProWrenching]

I’m glad you were able to get that project completed. I hope the Jegs fuel sender works well for you. As old as these trucks are, you’re not going to find NOS parts anywhere LOL!

[@Rick-xb5kq]

O well the unit from Jegs lasted about 13 months

[@cmf56]

Very helpful and thank you.

[@ProWrenching]

Thanks!

[@rickb8538]

Brass aftermarket floats are crud. Sending units are ok but replace the brass float with a plastic one.

[@henrytupper6959]

Thanks for your video. I have watched others that also tell you what to check if it fails. Mine works but not accurate. Run out at 1/3 of a tank. Any ideas thanks. Chevy van, tank under floor, 1967.

[@ProWrenching]

It could be the gauge, could be the sending unit. Need to check with a multimeter.

[@rudypalomino783]

Thanks

[@chiphazzard8173]

Well im takin the original out of my 72 today to replace with one i got off the jungle site and new one has a vent, old one doesnt. Not correct but it'll do i guess

[@kimcarner9077]

I’m trying to test my sender .. what wires are you holding the red and black Probes to exactly? Thanks

[@ProWrenching]

The black wire to ground and the positive wire to the terminal connector that goes to the sender wire.

[@chaningdodson4245]

Have you ever had one make your truck act like it was running out of gas an randomly die? Doing troubleshooting

[@ProWrenching]

It is possible for the fuel sending unit to be cracked or to have a leak at the flange. With a carbureted engine and a mechanical fuel pump on the engine, the fuel pump is sucking fuel from the tank. If you were having an issue with not getting enough fuel it could be because there is an air suction leak. It’s something that I’ve seen more on semi trucks with diesel fuel. A way to test would be to put a mechanical fuel gauge between the pump and the carburetor and check the pressure. Most likely if you’re having a fuel issue it will probably have to do with the carburetor or float level in the carburetor, I would think.

[@chaningdodson4245]

@@ProWrenching ok I have am edelbrok in line electronic pump I believe it's 4 to 7 psi rated, just put it on yesterday, had a regular sbc mechanical pump on it before an was having the same issue, just ran around the block an it did it again, this time it had a thin misty smoke coming from the air filter, like I backfired or something but I didn't hear anything, I hit the gas to go an it said nope an shut off lol

[@chaningdodson4245]

@@ProWrenching sits an idles great, revs an all, but put it in drive an go around the block its a guessing game when it will do it. Less then 2000 miles on this 355, mild cam daily 70 gmc truck

[@ProWrenching]

@@chaningdodson4245 if your fuel pump is sucking air, it may not be getting the right amount of fuel pressure to the carburetor. You can still check that with the gauge. Another way to check that would be to take a fuel line and run it into a bucket with the fuel pump on and see if you’re getting air bubbles in the bucket. If the fuel looks fine and the pressure is good I would want to check the float level in the carburetor.

[@chaningdodson4245]

@@ProWrenching ok ima try that, thanks man👋

[@lewisfloyd3801]

The wire that comes from the gas tank to the box under the dashboard. Is it suppose to be hot when you cut the key on?.

[@augustoescobar50]

No that's the signal wire

[@aureliogarza7937]

I bought one from LMC, only lasted about 6 months. Terrible quality.

[@ProWrenching]

It’s amazing how the first one lasted for 50 years and the second one only makes it one year. I had the same problem. I’m hoping this new one will last a little longer.

[@ProWrenching]

It’s amazing how the first one lasted for 50 years and the second one only makes it one year. I had the same problem. I’m hoping this new one will last a little longer.

[@lancegibson135]

Put a new one in