If I plug the return on a airtex 40736 will I cause fuel pressure issues, as in too much? Don't want to run another line for a return.

 

Most likely you will have flooding issues and hot restart problems. The fuel pump bleeds off a small amount of fuel back to the tank through the return line to keep the fuel and pump cooler. It also bleeds off pressure after shutting off the engine. Without the return line during a heat soak the fuel can boil and build up enough pressure to push the needle off the seat in the carb, flooding the engine. The return line is usually found on cars equipped with A/C.

 

You can plug the extra port and will have no problems. I have done this many, many times. Certainly if the car already has a fuel return line, you should connect it, but it is not mandatory on cars that did not come with one. Note that all aftermarket high perf pumps (like Holley) have the fuel return port and a pipe plug to install if your application does not require the return port.

The return port is nothing special, just a calibrated "leak" back to the tank. The pump always pumps more fuel than the carb needs. Without a return line, the pump diaphragm just "dead heads" and stops pumping.

 

Trying to figure out if I was sold the incorrect fuel pump.

1972 Cutlass Supreme 350 4BBL with A/C (sorry for posting in big block section - but this thread seemed to be on topic)

I ordered before looking at it closely, and the one that showed up has 3 connections at the top - the one that came out of the car has 2. (see attached photo)

Looking at the assembly manual (courtesy of wildaboutcars.com) pages 8-110 and 8-116 show 2 different setups, but don't seem explain the application.

Is there a way of figuring which one came with the car, or is one of those things that sometimes was one way, and other time the other?

If I look at the detail on 8-116 of the 2 hoses snaking through the bend of the frame, it looks like what is on my car, and that it has not had the third line removed or plugged up. (see attached photo)

Confused and would appreciate any guidance...

 

Tripple D: your car did not have the return line. You can use the new pump but with the return fitting capped (see Joe's post above), or return it and get the proper one.

Cheers, Peter

 

They gave him the proper pump.
His post tells us, 72 350 with air.

Hopefully, his return line had been plugged
at the frame and not left open.
Dirt daubbers love those small holes.

 

hmmm.
but this is what puzzles me - if you look at this photo, the clamp (and those that go further along the frame towards the tank) looks unmolested and correct with the 2 lines instead of 3 (as is seen in the illustration).

Does that make sense?

 

Looking through The 1972 Oldsmobile Chassis Service Manual, I found, on page 8-3, a figure: "Fuel Return Line Usage Chart" that states that all 350 CU. IN. A-BODY do not have a fuel return line (see attached image).

Thoughts?

 

My mistake.
All the A-body cars I have had
with a/c had the return line. Or so I thought.
Granted, all were 455 powered.

 

I have a 1972 that came with a 350 and A/C, which from the earlier ost tells me that it did not come with a fuel return line. It seems that when driving on hot days my car does not always want to start easily after driving. Does this sound like a vapor lock or percolation issue? and would it be advisable to run a fuel return line? also i recently dropped in a 455

 

Other than the hassle of installing it, there is no downside to running fuel return. By circulating hot underhood fuel back to the tank to cool, you will definitely reduce or eliminate any vapor lock or percolation problems. Now, whether these are causing your starting problem is a different question that will require more info to answer. And welcome to the site.