Fuel tank sending unit

Motorcity Mustang said:

Sounds like quite a few folks may not be familiar with the 71 429 CJ cars. All 71 429 CJ (not SCJ) had a quadrajet carb and a 1/4 return fuel line from the fuel pump back to the sending unit. That was the only Mustang from 71-73 that had a fuel return line. Thus the difficulty finding a correct fuel pump or sending unit, but they are out there. There is a guy making the sending units (he makes them for Torino and Mustang), but the fuel pumps, you have to find originals or rebuild yours.

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That would be only 71 as 72 and 73’s did have the 429 CJ option.

Stanglover said:

Did you read 7173Vert's post above?

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Yes, I did read it, more carefully after you pointed it out. I skimmed over the preceding info a bit too quickly I fear, and missed the 1971 429 detail. My bad. I will now try to correct that oversight. Had I taken the time to specific there is a difference with the 429 sending unit in 1971, as opposed to having taken the part # I found from a 71-79 Ford Parts Manual I would have been "more correct" by having left door open for a certain level of subjectivity. I popped open the Parts Manual that covers 1971 Ford Parts, and indeed found the sending unit with two outlets, for a 429(CJ). I put together another document (attached) that tries to ferret out more detailed info re: the reason for the 2nd fuel connection on the Sending Unit for a 429(CJ), but I am guessing it is not for the Fuel Evaporative Control System, as I saw no other indications the same Evap System for most Mustangs being any different than for a Boss 429, Further, the 2nd vent connection for the 429(CJ) Fuel Dending Unit does not seem to have a Vapor/Liquid Separator like the VaporLiquid Separator at the upper center of the fuel tank on a Mustang. ]

The info from MotorCity Mustang preceding this entry seems to explain what that 2nd vent line is connected to. I added his info to it to the PDF I put together for. and attached to, this post. Very cool to see... I am glad you asked me the question re: if I had seen the prior info or not. Otherwise I would have not likely been aware of this little wrinkle for a lot longer time.

mrgmhale said:

Yes, I did read it, afteryou pointed it outt. I skimmed over the preceding info a bit too quickly I fear, and missed the 1971 429 detail. My bad. I will now try to correct that oversight. Had I taken the time to specific there is a difference with the 429 sending unit in 1971, as opposed to having taken the part # I found from a 71-79 Ford Parts Manual I would have been "more correct" by having left door open for a certain level of subjectivity. I popped open the Parts Manual that covers 1971 Ford Parts, and indeed found the sending unit with two outlets, for a 429(CJ). I put together another document (attached) that tries to ferret out more detailed info re: the reason for the 2nd fuel connection on the Sending Unit for a 429(CJ), but I am guessing it is not for the Fuel Evaporative Control System, as I saw no other indications the same Evap System for most Mustangs being any different than for a Boss 429, Further, the 2nd vent connection for the 429(CJ) Fuel Dending Unit does not seem to have a Vapor/Liquid Separator like the VaporLiquid Separator at the upper center of the fuel tank on a Mustang. ]

The info from MotorCity Mustang preceding this entry seems to explain what that 2nd vent line is connected to. I added his info to it to the PDF I put together for. and attached to, this post. Very cool to see... I am glad you asked me the question re: if I had seen the prior info or not. Otherwise I would have not likely been aware of this little wrinkle for a lot longer time.

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As my signature says " I learn something new every day" and I did.

Stanglover said:

I confess to being a little confused. You say a c code 429, but you don't say what car. Nor does your info on the left.
If it's a Mustang 71-73, then the tanks are the same. The sending unit does not have a return but there is a vent tube from the charcoal canister in the engine bay to the top of the tank.
Original units are hard to find and many repops are not that good, however the best I found for my car was the Dorman 692232. Calibrate with an empty tank plus 5 US gallons of gas. That should read 1/4 full. If not jack the left side high enough to be able to remove the unit and adjust the arm without spilling gas. Use two floor jacks is what I did.
This is an original unit with number.

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It’s a 71 Mach1 429 cj . So it has A/C and a C6. They all have the vent on the top of the tank. Mine had a Carter mechanical fuel pump with a return . It’s just a 1/8” pipe for the return and the usual 3/8 supply. Well I have to revisit it. There is a slight leak( seep at most) . It had originally a Rochester spread bore. I changed the intake and never had the original carb..now it has a Holley 800dp list number. I’ll try to find a sender.

I got one from Craig White and never had any problems with it so far.