74 LT Z28 fuel tank & sender

erials

New Member
Apr 9, 2019
21
I’m trying to change out all of my fuel lines, tank and sending unit and having a heck of a time finding the right tank and 2 line sending unit. The tank I see everywhere for a 74-75 car has filler neck that’s about 2 inches shorter and uses a later model screw cap.

On the sending unit, I can not even find a listing for a fuel sending unit for the 74 with a return line on it. All I’m seeing is the 1 line fuel supply line for the 74 V8 cars. Must be very few cars made with the return line in 74.

My Z car tank has 2 lines on the sender that run down the passenger side of the car and a vapor line that runs separate from the sender Down the drivers side next to the intermediate brake line.

Anyone run into this before? Does anyone happen to have a source for the tank with the correct neck on it and a 2 line sender for 74? I’m finding that quite a few parts are specific to 74 cars only.
 

Bobs RPO Z/28

New Member
Mar 10, 2021
12
Illinois
I’m trying to change out all of my fuel lines, tank and sending unit and having a heck of a time finding the right tank and 2 line sending unit. The tank I see everywhere for a 74-75 car has filler neck that’s about 2 inches shorter and uses a later model screw cap.

On the sending unit, I can not even find a listing for a fuel sending unit for the 74 with a return line on it. All I’m seeing is the 1 line fuel supply line for the 74 V8 cars. Must be very few cars made with the return line in 74.

My Z car tank has 2 lines on the sender that run down the passenger side of the car and a vapor line that runs separate from the sender Down the drivers side next to the intermediate brake line.

Anyone run into this before? Does anyone happen to have a source for the tank with the correct neck on it and a 2 line sender for 74? I’m finding that quite a few parts are specific to 74 cars only.

My car came with a new tank that the previous owner had desoldered the orig filler neck from the rusted tank and swapped them out resoldering it in the new tank. Make sure old tank is empty and dried out before heating up the solder joint.

As for the sending unit I ordered one with 2 lines for a 1975 from NPD, it was less than $60 and while the lines are not 100% perfectly bent it works fine. Save the line clips that hold the lines to the tank flange and dont forget to unhook the tank vent line to charcoal canister before dropping it out.
 

Jonesy

Veteran Member
Jun 7, 2008
547
Minnesota
what's wrong with your original tank and sending unit? I think you may have a tough time finding original replacement parts.
 

erials

New Member
Apr 9, 2019
21
Rust damage all around the seams of the tank and the lines on the sending unit.

I cleaned up the sending unit and am prepared to re use it since there are no holes in any of the lines. It actually cleaned up better than I thought it would. The tank itself is very clean on the inside no rust or particles at all. However it’s badly pitted and flaky on the outside. The part of the sending unit that goes inside the tank is clean and rust free thank goodness. I’m afraid the tank however, is beyond the ability to re-use.

The vapor line on the tank is so corroded that it’s got holes in it after the first 8 inches or so.

The original filler neck appears to have been purposely dented in along the top facing side of the tube. I thought this was odd and possibly done by a previous owner but in looking at detailed pics of the tank and neck on Charlie’s 979 original miles 74, his appears to have the same hammered dents in it. Have you guys noticed this on your 74 filler necks? Did GM have to tweak the necks to fit? Weird.

I suppose I’ll try removing the neck on mine for clean up and re-use on a new tank.

Here are some pics of what I’m working with.


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Last edited:

erials

New Member
Apr 9, 2019
21
Yes, mine has dented neck too.

Can’t really say why but it does appear the necks were dented by GM but I can only speculate as to the why. Doesn’t look like a clearance problem in the body opening behind the plate as there appears to be plenty of room all around.

Perhaps it has to do with the fact that shoving the gas pump handle into the opening too far may have a tendency to damage the tail light panel paint and GM recognized this as a problem and dented the filler necks so the pump nozzles could only be pushed in so far protecting the finish on the tail light panel. Who knows?

Anyway got the old neck soldered on the new tank and installed. I took the advice here and used a 75-76 sending unit that I had to tweak a little. Also changed all the steel lines out to new stainless lines including the vapor line as well as all the steel and rubber brake lines.

Had to tweak the fuel supply and return lines with my heavy duty tubing bender near the back of the car as the repro lines for the passenger side of the car were both missing a bend in the same spot. Vapor line and all the brake lines were a good fit requiring very little tweaking. All is good and had no leaks to contend with after the install. A little soaking in Evaporust for all the mounting clips and bolts and all looks brand new again.
 




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