How To Convert Your Classic Car's Fuel Sending Unit Into An EFI Fuel Pump Module

10 min read

How To Convert Your Classic Car's Fuel Sending Unit Into An EFI Fuel Pump Module

10 min read

Holley's line of muscle car EFI fuel modules make the process of converting your older vehicle to run on fuel injection simple by incorporating everything you will need, from the Hydramat to the 255 LPH fuel pump and more, onto a stock-style sending unit that fits into the OEM fuel tank like it came from the factory that way. Holley covers a wide range of applications, from Tri-5 Chevrolets through GM G-body cars. Corvettes, Mustangs, GM Squarebody trucks, Jeep CJs, and more have a module that will fit right into the fuel tank. But what if you have an application that doesn't have an option available currently? You can use a Holley Sniper In-Tank Retrofit Fuel Module, which installs simply by drilling and modifying the fuel tank.

Opposed to modifying the factory tank? What then? With 1970s, 1980s and 1990s cars gaining in popularity and the cost of older, more popular models going higher and higher, cars that used to be largely ignored are now being looked at as affordable options. And for a younger market, seeing these older cars for the first time might be the spark of inspiration that they need to pick up a wrench and build something of their own instead of waiting for the day they can bid at an auction for some old metal.

In our case, we have a 1976 Dodge Charger that is being prepared for a conversion to fuel injection down the road and the owner's first goal was to get the fuel system prepared to handle an EFI. While Holley does make an EFI Fuel Tank Module for a 1968-1970 Charger, we knew that the major redesign that the Chrysler B-Body platform underwent in 1971 and the 1975 re-skinning meant that we couldn't bet on that module working. To be safe, we dropped the fuel tank out of the car and test-fit both the 12-384 module for the 1968-1970 Charger and the 12-389 module for 1963-76 Chrysler A-Body (Dart, Duster, etc.) to see if either unit could work in our Charger's tank. The A-body module was immediately ruled out, since the sender is mounted to the top of the fuel tank instead of the side, like a B-Body. The 1968-70 Charger module was close, but we were correct in our assumption that there would be a major design change that would cause a problem, as you can see below:

The one thing that we did notice is that the 1968-70 sending unit style and the 1976 sending unit style were close enough in design that if we used the 1976 pickup tube design and float, and combined it with the fuel pump from the EFI Fuel Pump Module, that we would wind up a drop-in-ready sending unit that could handle fuel injection. So...we did just that, with one caveat: we would not be able to incorporate the fuel pressure regulator onto the 1976 sending unit. Not that big of a deal, really...we'd run an external pressure regulator and plumb a return line back into the tank. Follow along to see how we prepared the fuel tank of this 1970s sled for a modern-day fuel system!

Charger tank before

That's not pretty, but that's what the fuel tank of a 1976 Dodge Charger looks like after over forty years of use. Honestly, this could've been a lot worse. After draining all of the fuel out and allowing the tank to vent out the remainder of the fumes, we tossed it on the bench and got to work.

With locking compound on the threads, we tightened the nuts on the bulkhead adapters down on the wires coming through the sending unit. The compound needs at least 24 hours to dry before any fuel is introduced into the system.

Charger custom pump into tank

The next, crucial step was to take all of the pump assembly and get it into the fuel tank without harming anything, least of all the Hydramat. It's recommended that you put masking tape around the edges of the port to keep any rough edges from tearing the Hydramat as you install the pump.

completed module outside

On the outside, the only giveaways that something has been modified are the two wires from the sending unit and the return port...and maybe the shiny new sending unit. Once this fuel tank is re-installed into the Charger, none of this will be seen unless someone goes out of their way to look for it.

Charger inside tank shot

What nobody will get to see in person is the layout of that new sending unit as it's mounted in the tank. The fuel level float clears all of the new components, the Hydramat will always be in the fuel, and the return port tube is off to the side of the Hydramat and low in the fuel level.

1976 Dodge Charger Daytona door

While this project required a few hours of assembly and a few days' worth of time to prepare for properly, we're very pleased with the outcome. Just be sure that if you are going to take on a custom job like this, that you do your homework prior to making the first cut or before you drill the first hole. If you have any questions or want to run your idea by one of our technical support staff first, you can reach out to Holley's team of experts at 1-866-464-6553 or email a technician using the Technical Request form, found under the Support tab at

Parts Utilized

PartPart Number or Item Sourced From
Sending unit, 1974-1976 Chrysler B-BodyLiland Global, SUDG-09
Sending unit lock ringSpectra Premium, LO06
Earl's -6AN Bulkhead983206ERL
Earl's -6AN Strat-O-Seals178009ERL
Earl's -6AN Male to 5/16ths Barb750156ERL
Earl's -6AN Bulkhead Nut592406ERL
5/16ths Nylon Fuel LineDorman p/n 800-074
9-11mm Stainless Hose Clamps(any parts store)
Wire Bulkhead FittingsSourced From Holley Sniper 19-165 
350 LPH Fuel PumpSourced From Holley Sniper 12-384 
HydramatSourced From Holley Sniper 12-384
Submersible Fuel HoseSourced From Holley Sniper 12-384
Earl's Vapor Guard Hose Clamps, 5/16750005ERL
Wiring PigtailSourced From Holley Sniper 19-165


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