Hi everyone. I have an 83 TA that I just bought a 92 305TPI for and am looking at doing this swap. It seems there isn't actually a lot of detailed info on this swap on here unless I am missing something. I want to do as close to a factory install as I can and I don't have a donor car to look at so I have some questions. The first one is I have seen pics of the TPI tank sending unit and there are four lines coming out. Obviously one is a fuel feed and one is a fuel return but what are the other two? Also, from the pics I saw, I can't tell how the sending unit lines attach to the chassis lines. If anyone can help me out (maybe someone that has done a fuel pump on one of these cars) I'd be very appreciative. Ryan

the TPI fuel lines are different that what you have on your car, to do a factory looking swap, you need a new set of lines for a TPI car. The pressure line has a threaded connection from the body lines to the tank lines, the other cars dont. Maybe TBI ones do, not sure.

one line is the feed, is the 3/8 lines, the smaller 5/16 in the return, one line goes to a little plastic rollover fitting thats mounted to the floor in front of the tank by the driverside frame rail, i believe the bracket that mounts the brake lines flex line is the support for the rollover valve. the other lines goes to the front of the car and into the charcoal canister.

I figured I would have to put new lines in, Classic Industries has the feed and return for $69 each. The charcoal canister makes sense, but I am not quite sure what you mean by this rollover fitting you are talking about. Could you explain a little more about that? Is it some kind of pressure relief valve? Thank you very much for your time.

Its not so much a rollover fitting as a pressure relief fitting. Its a complex little plastic gizmo GM made to keep pressure inside the tank equal to atmospheric pressure. I believe it opens and closes at pressure above or below 1 psi.

Don't bother going to Autozone for it, they don't carry it nor do they know what it is. I went directly to the dealer for mine, 60 bucks later I walked out.

An easy way to check if its working right is to fill the tank up, and drive the car for a bit (until there is a noticeable difference in fuel, say 1/4 tank). Then, slowly unscrew the gas cap. Listen for any hissing when you do this, it will be the tank equalizing its pressure to the atmosphere. If the car hisses, get a new one. If not, its doing its job. That little piece of **** was responsible for two ruptured fuel lines inside my tank.

nomad, you got a part number? Mine hisses.

That is interesting, I just did a TPI swap and never noticed a fourth line. How does this line get installed, where does it come out from. Dale, if you have the tanjk out can you post the pic.

Tank doesnt have to be out to replace it. Its on the brake line bracket, behind your left tire.


:edit: Mine was also a TBI car. I think its on all injected cars, because my v6 had one also.

The four lines are as follows
Feed line
Return line
Fuel Vapour line that is sent to the purge can under the hood
A Breather line that (if I am not mistaken) has a check valve on it.

Just like //<86TA>\\ said

Anyone have any pics of which line is which? I unplugged mine without labelling them. The feed line is easy to identify, not sure on which one is which cause the other 3 just drain into different locations.