Newer efi tank in my 79 coupe

[79mustang]

Hi guys. Im in the process of swapping a efi tank into my 79 coupe. Ive ordered the tank, grommet for the filler neck, pump hanger, grommet for vent valve, 86 sender, efi tank mounting straps, and a hfp pump. Couple questions i havent found answers to, and yes i have searched. Lol. Ive read the filler neck itself is bigger on the 79-81 tanks and wont fit into the tank. Another thread i read said theyre the same. Which is it? Do i need to change the plastic housing the neck bolts onto if i do need a efi neck, and what about the rubber gasket that goes around the neck to seal out stuff from getting into your trunk. Is the rubber gasket different? Can i use the vent valve out of my old 79 tank in the new efi tank? Thanks for any help.

[82GTforME]

I can't answer the question about the filler neck but I know the 79's had smaller tanks. I believe most replacements are the larger, leter ones so you may have massaging and minor mods to do to install it.

Just looking and I see American Muscle only has 81-86 non-EFI tanks. Nothing earlier. Maybe due to a size change.

From the library

1979 (Canada): 10.4 Imperial gallons
Attachment 74626

1979 (US): 12.5 US gallons


Assuming the tank I got is 1984: (Canada) 12.8 imperial gallons


Assuming the tank I got is 1984: (US) 15.4 US gallons

They are 12.5 gallon tanks and you can get new tanks for the 79-80 made by spectra if I remember correctly. The later tanks will fit but you have to massage the trunk floor for the hump in the newer tanks. You also have to move the straps or lenghten them something like that.

[79mustang]

Ive saw in other post that some massaging of the spare tire well is needed and that i will have to fab up some brackets for the newer straps to work. Just really curious about the filler neck. Im looking at some newer ones on ebay but dont wanna waste my money on it if its not needed.

[2nd chance cobra]

The tank is larger. The filler neck is a giant see you next Tuesday to get in I'm stretching the bujesus out of mine with a large socket.I'm using the 79 straps, you just need to reshape them a little. The right side strap has been moved right the width of the strap, I'm still working on that one. And I think there is some issue with sender resistance values over the years, I have not yet addressed that . Left side strap goes right on. As far as massaging the floor, I have not done that but I can appreciate the desire. And I cannot find a bushing for the early filler. I have a newer filler neck side by side and I don't think that's the easy way. Hope that helps

[79mustang]

So your saying the 79 filler neck and the efi necks are the same or no? Sorry but im confused.

[2nd chance cobra]

The 79 filler neck is bigger and has a 4 hole mount vs. a 3 hole mount on the later. For reference I'm comparing to a 90. I tried to get a pic,but it wouldn't turn out in the dark

[79mustang]

Ok thanks. I saw a efi neck with all the parts on ebay earlier. Looks like ill have to grab it up.

[2nd chance cobra]

like this one? $15 plus shipping.

[79mustang]

I may have found one local to me. Ill let you know if i dont get it.