Dose anyone know off the top of there head
what setup is correct for my car. Or what I can do.
I have been gathering info all day.
I have a three line fuel pump 1 line sender
”and only two lines running from front to back.
A fuel line and a return/canister Line
Or can you have three with a return and canister?
anyone know. I just want to put the car back together it’s just a driver.


Fuel tank

Canister line hooked to return incorrectly main fuel line

 

I believe the cars with AC would have the three line fuel pump so that it circulates fuel to reduce the heat of fuel during hot weather. I will let others correct me, but I believe that did not start until 1972. Your last picture has nothing to due with the fuel pump, it just gathers the vapors from the fuel tank and routes them to your charcoal canister on your passenger side wheel well. The card will run on either the three or two line pumps, you just have to cap off what you don't use.

 

No, his car is a '71, and it uses a return line as well according to the factory service manual. He has another whole thread on this, and he's been pm-ing me on this all day. I think all his questions have been answered, but he seems to want to keep asking them.

His car has a single-line fuel tank sending unit and a three-line fuel pump. The sending unit is apparently wrong because his car has A/C, and all '71 Oldsmobiles with A/C used a return line from the fuel pump back to the fuel tank. So the three-line fuel pump is correct, and he needs to replace the single-line sending unit with a two-line unit if he wants to make the car factory correct. Apparently a prior owner just capped the return line from the fuel pump as there is no line on the sending unit to connect it to. It appears that a prior owner replaced the sending unit with an incorrect one as it has only one line, and all A/C cars used two-line sending units.

 

Well apparently my '71 convertible is the same as his, with AC and no return line, but mine has a 2 port fuel pump.
Now I haven't dropped the fuel tank to verify how many ports are on the sending unit like he has, so I can't say I have the correct pump and connections.

He has dropped his tank and the single port sending unit looks to be a lot older than the shiny new fuel pump with a return port. So which is likely to be incorrect?

The key to this is: Does his car have a return line to the tank?

If not, the fuel pump is incorrect.
If yes, the sending unit is incorrect.

 

Johnny, do you have a steel return line ran down the frame from the front to the rear? I doubt anyone removed it if it was ever there. If it’s not there then you have the wrong fuel pump. If it’s there you have the wrong sending unit. As far as how all the vent lines are suppose to be ran I’m not sure on that just consult your chassis manual.
*edit* just reread that you do have a return line on your frame doesn’t that answer any questions?

 

thanks!

 

Yes thank you ,
The only thing I don’t understand is that there is two lines running along the frame one for the fuel and one for the return? or is it for the canister?
I bought the 2 line sender and installed it.
i just have to empty some gas out. To install it.
so I guess I will either cap the 2nd line off the sender or hook up the 2nd line and cap the canister line

 

Here's the chart from page 8-3 of the '71 Chassis Service Manual.

According to the '71 Dealer Specs Book, the base engine in the Cutlass Supreme was a 350 with 4-bbl. Based on this and what it says in this chart, I would conclude that such a car would NOT have a return line, regardless of whether or not it has A/C, as it would be in the "ALL OTHERS" category at the bottom of the chart. An optional engine on the '71 Supreme, for a $33.70 deduction, was a 350 with a 2-bbl. If such a car had A/C, then, according to this chart, it WOULD have a return line as it would be the fourth entry on this chart.

In short, if I'm reading this chart correctly, the ONLY 350-equipped '71 Oldsmobile that would have come with a return line would be an A-body with a 350, 2-bbl carb, and air-conditioning.

JohnnyOlds442's car, if I recall correctly, has A/C, 350, and a 2-bbl. That would make it the fourth entry on the chart, and it should have a return line.

Your (Fun71) car, if has a 4-bbl carb, would apparently not have a return line, so if your car does has a 4-bbl, your setup is correct.

 

The canister is on the right front fender, right? It has two connections on it. One connects to the carburetor, and we all know where that is. The other connects to the standpipe, and that's located behind the rear seat. Both of these connection points are toward the front of the car relative to the fuel tank. There is nothing the canister connects to that would require running a line along the frame.

If there are two lines running along the frame, I would guess one is the main fuel line and the other is the return line.

Remember, there are also supposed to be three additional lines to the rear of the car, all coming from the standpipe. They connect to the three "vent tubes" on the rear of the fuel tank.








No. The second line off the sender is the return line, and it connects to the third port on the fuel pump. You said you fuel pump has three ports with one of them capped off. The reason it was capped off was because the sending unit you had in your car had only one line where it should have two. Now that you've installed a two-line sender, you have a place to connect that third port from the fuel pump.

The canister is connected as described above.

 

Well I guess that answers any questions I had about my setup. Thanks.

 

So you do have a 4-bbl?

 

Yessiree, QuadraJet is the only carburetor for me.

 

Was the car born with that carb?

 

Yes, it has most all the Supreme standard equipment.

 

Yeah I’m a Quadrajet guy to but this car came with this two barrel and it’s staying that way.
Less chance to want to open up those four barrels this is a cruiser for sure not a bruiser

 

Cool. Thanks.

 

The statement that ALL cars with AC used a fuel return line is absolutely incorrect. Most 350 cars with AC or without didn’t have a fuel return line ... 455 cars did. This guy's car has had a fuel pump change at some point, not an issue of an incorrect sender at the tank. Nobody mysteriously removed the fuel return line. Have you ever replaced the entire line setup, front to rear? It’s an adventure.

 

The fuel pump is incorrect; you should not have a return line from the fuel pump. You have 2 lines running down the passenger side frame rail: 3/8" line is the supply to the fuel pump, the 1/4" line is the emissions vapor line which connects the charcoal canister (on the RH side behind the headlights) to the standpipe (behind the back seat). Follow the drawing Jaunty75 provided to connect the hoses properly.
Rodney

 

AMEN. Good summary. Absolutely correct. That's all you need to know.