I've been having issues with the gas gauge for the plastic side tank in my 79 4x4 F150. It was always reading empty and I finally localized it to the sending unit. I put a new one from LMC in a year ago when I had the bed off so always figured it was something else. Anyways, it turns out the float arm was too long (roughly 10") and was limited in its range of motion by the opposite wall of the tank. I also measured the filter and intake tube and realized that the filter was positioned about 1.5" above the bottom of the tank. My fill ups to this tank max out at about 18-19gal so obviously this sending unit leaves quite a bit of fuel still in the tank.

So... either I have the wrong sending unit or the wrong tank. I'm thinking I need a sending unit with a longer intake and a shorter float arm. Researching on FTE for the correct SU I came up with D9TZ-9275-A. I just need a little reassurance that I have the correct tank (26gal plastic tank with steel case). My truck is a frankenstein from the PO. Any help would be appreciated. Thanks!

 

Yeah I don't think the plastic tank came stock and I believe that they are only 19 gallons. When you bought the sending unit it was probably meant for the correct tank that should be side mounted in 79. Someone else should be able to chime in with better info, but I'm pretty sure you don't have a true 79 side tank.

 

Sounds like the wrong sending unit for sure. I always thought that 4x4 trucks came with a plastic side tank, 2wd truck came with metal side tanks. But according to the info below not always. Here is some FTE old post info thanks to ND/mikeo0o0o0.

Is your truck a long bed 4WD? Does it have evaporative emission system? There are two possibilities with the plastic tank.
79 F150-350 regular cab, 133" WB 4WD, w/ evap. emissions system, 24.8 gallon mid-ship plastic tank
D7TZ-9002-C
Same w/o evaporative emissions system 26.3 gallon plastic tank
D7TZ-9002-D

Mid ship fuel tank support cradle part # D7TZ9K134A - Reinforcement Assy. And more info in it here. https://www.ford-trucks.com/forums/8...ank-mount.html

And mid ship sending unit info D9TZ-9275-A (replaced D7TZ-9275-H & D8TZ-9275-D) .. Fuel Sending Unit-Use w/Mid-Ship Plastic Fuel Tank / Includes float, filter screen and gasket / Obsolete

Marked: D8TF-AA, AB, AC, DA; D9TF-AA.
Applications: 1977 F250 Regular Cab 4WD from serial number Y20,001 (not a High Boy) / 1978/79 F150/250 4WD Regular Cab / 1979 F350 4WD Regular Cab.

D9TZ-9275-A =
GREEN SALES CO. in Cincinnati OH has 1 = 800-543-4959.
NOS PARTS LTD in Waxahachie TX has 1 = 972-937-2201.
HIGH BUCK! BOB ALLEN FORD in Overland Park KS has 3 = 800-676-0675.
COLLECTORS AUTO SUPPLY in Oroville WA = 800-414-4462 (only number listed).
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D7TZ-9275-H =
ANTIQUE AUTO SUPPLY in Arlington TX = 817-275-2381.
WESLEY OBSOLETE PARTS in Liberty KY = 606-787-5293.
GREEN SALES CO. in Cincinnati OH = 800-543-4959 / 513-731-3304.
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D8TZ-9275-D =
JST AUTOMOTIVE
GREEN SALES CO.
WESLEY OBSOLETE PARTS
D9TZ-9275-A is the correct one for 1979 F350 4wd regular cab midship tank?