Blazer fuel sending unit quesitons

[buckshot33]

ok. I have this tank:

Its a 31 gal. tank out of a blazer but I dont know what year. I fabbed this tank into the back of a Scout and am in need of a fuel sending unit. Ive been looking at my catelogs and have found several different sending units. Some have 3, some have 4 ports and they have different senders for different year blazers.

What are the differences in the units? Can I pick any sending unit and put it in this tank if its for a 31 gal tank? I noticed that pre 78 units are about 80 new and after 78 they are about 160 new. in 87 they go up to 330 because of the intank pump. I will have no clearence problems above this tank and plenty of room for any port combonation. Will any sender fit into the top of this tank? I already bought the lockring and it says it works from 73-91 so that should mean that all they 31 gallon fuel sending units should work, the differences is the port configuration.

Can somebody confirm this before I spend 80 on the wrong sender then turn around and have to spend 160?

 

[45acp]

Michael, I don't think it matters beyond the configuration of the ports. Originally they did not have a return (vapor lock) and they installed a return line to the vent line. Then they made the change and put in the extra port. They also changed the filler neck size and I don't remember for sure but I think it was 1.5" and went to 1.75" Diam. I just put a 1983 tank into a 1980 and this is what I found.

1980 had 3 ports - Vent = 5/8 Diam. - Supply = 3/8 Diam. - Canister = 5/16 Diam. and Return was feed into the Vent line with a 1/4 Diam. Tee.

1983 had 4 ports - Same as above but a additional Return = 1/4 Diam.

 

[buckshot33]

Thanks a bunch for the reply. This was a big help.

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