How To Replace a Fuel Tank Sending Unit on a 1978 Dodge Truck

By | March 18, 2022

How To Replace a Fuel Tank Sending Unit on a 1978 Dodge Truck
Recently I began to have fuel problems on a 1978 Dodge truck.

I did all the obvious things, such as changing out the fuel filter and pump. which at first seemed to solve the problem, but it came back.

Finally, I pulled out the fuel tank sending unit, which was rusted up good clogging up the lines.

I was lucky enough to have a wooden bed in the truck I worked on, so I was able to pull the boards up to help remove the Fuel Tank.

Most trucks will not have this option and need to drop the tank from under the truck.

There were three straps on the tank in my 78 Dodge, which has an 18-20 gallon tank.

Some trucks have a 30-gallon tank, so there will no doubt be some differences between truck body types.

I ordered the sending unit from eBay, which saved me money. Be sure to call around and see the best price for your location.

*This site contains affiliate links for which a commission earned.
Click Here to See Prices on eBay

After pulling the unit, the old gas line was in bad shape and was cheap, so I also replaced it.

It uses a 5/16 Fuel Line which I ordered from Amazon.

Here is the Fuel Line I ordered on Amazon. (Paid Affiliate Link)
LDR Industries 516 F5165 5′ Bag Fuel Line, 5/16″

How To Replace a Fuel Tank Sending Unit on a 1970s Dodge Truck

  1. The sending unit is located on top of the gas tank. Depending on the truck body style, the tank will likely need to be dropped.
  2. How To Replace a Fuel Tank Sending Unit on a 19787 Dodge Truck Step 1
    The bed on my 78 is wood, so I didn’t have to drop the tank but still did to be sure all the rust was flushed out.

    If you can get to the tank from the bed as I did, this is the best option; otherwise, the tank will need to come out.

    There were three straps holding the tank in with the bolts rusted up good.

    I also drained all the gas out with a spare electric fuel pump I had lying around.

    The tank is plastic, so as long as it doesn’t leak, it will only need a good cleaning. Also, be sure to check the inlet pipe where the gas goes in for any rust; mine was rusted good.

  3. Unscrew the hose clamps and the wires. The sending unit is held in place with Philips screws which are simply unscrewed to pull it out.
  4. The unit simply pulls out.
  5. I ordered a new unit from eBay since it was the best low-cost option for me. Check around to see what is the best price for you.
  6. I compared the old unit with the new one, which was the same.
    How To Replace a Fuel Tank Sending Unit on a 1978 Dodge Truck Out 2
    The new unit also came with a new gasket.

  7. Bolting it in is straightforward with the gasket and tighten the screws. It only goes in one direction.
  8. How To Replace a Fuel Tank Sending Unit on a 1978 Dodge Truck Install 3

  9. The old gas hose was in bad shape, so I replaced it with a new 5/16 gas line hose.
  10. How To Replace a Fuel Tank Sending Unit on a 1978 Dodge Truck Install 4
    After flushing the gas tank and installing the new sending unit, it solved my gas problem and is running good again.

Bob Thomas
Latest posts by Bob Thomas (see all)

8 thoughts on “How To Replace a Fuel Tank Sending Unit on a 1978 Dodge Truck

  1. William O'Connor

    In this article, their are two two pipes coming out of the sending unit. The larger of the two pipes goes to the overflow on the filler neck and the smaller one goes to the fuel pump. If you have a third pipe… it will go to the charcoal canister under the hood along with the vent hose from the white check valve at top of the tank. The two electrical leads go to the fuel gauge and to ground.

    1. David

      On my 75 there is 3 hoses one is short and open you said goes to canister which isn’t on truck can I block that line so it don’t leak ? Or smell like it m leaking gas?

  2. Andrew buscher

    And replace both sides of the fuel level sender wire connector under the hi-beam switch on the floor. Always intermittent.

  3. Kelli Johnson

    What is the J shaped piece that attaches to the smaller hose that clamps on to the fuel sending unit for?

    1. art carlson

      the 2 white wires go to sender inside tank? right , i dont see them going anywhere? i have a bare post, with no wires attached to it, other wire is grounded to frame. thanks

  4. Eric Morrow

    I’m looking for a 1979 dodge lil red replacement gas tank. I have looked everywhere. If you can find a good one i will make it worth it for someone.

    1. shawn young

      Hey Eric – Did you ever find one? if so, where? I’m on the hunt for one also. ‘

    2. Vicki R Turner

      I got a new gas tank for my 78 Dodge Tradesman from Rock Auto. Also found the J-bolts at Partsmix. Hope that helps.


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