That makes all the difference in the world, thanks for clarifying. My question is: how do you seal off the pressure and return lines, 100%, simultaneously when the pump shuts off?

 

60psi is borderline, and the leakdown is excessive. The problem could be in the plenum or in the tank. To determine where it is, you need to isolate the pump from the rest of the system. The easiest and safest place to do that is at the fuel filter outlet. The pressure tester must connect directly to the fuel filter outlet with all fuel pressure and flow ending at the tester, (no fuel being allowed to the engine). When the pump is activated, it will test maximum fuel pump output pressure, and the ability of the pump to hold pressure.

You will need to make an adapter that fits between the tester and the fuel filter outlet. It will require 1 Dorman fitting #800-121 ~$13.00 available at most auto parts stores, (this will connect to the fuel filter outlet). Also need a brass adapter(s) with a 1/4" MFL fitting on one end, and a 3/8" male hose barb on the other end. These are available at Lowes, Home Depot, or a good hardware store. You will also need a 3' section of fuel injection rated rubber fuel line, and 2 hose clamps, (also available at most auto parts stores). The rubber line will connect the Dorman fitting to the brass hose barb. The pressure tester will connect to the 1/4" MFL fitting. This adapter will work on 1997 and newer S&T series vehicles.

In the underhood fuse panel, there is a vacant terminal next to the fuel pump relay. It is referred to as the "fuel pump prime" terminal, and it's used for activating the fuel pump during diagnostics. The circuit goes directly to the fuel pump motor.


Connect the adapter and pressure tester to the fuel filter. Attach one end of a 14ga fused, (20amp) jumper wire to battery positive. Connect the other end of the jumper to the pump prime terminal and check for fuel leaks at the tester and adapter, repair if necessary. When the fuel pressure stabilizes, write it down. Disconnect the jumper wire. Wait 10 minutes and write down the pressure reading. Post the readings. The results of these two tests, along with your readings at the service port, will tell where the problem is.

In your first post you mentioned a backfire when starting: This is not a fuel delivery problem, it is ignition related, and may also be what's causing the service engine light to blink. You also mentioned noise from the distributor, and I agree with LannyL81, it's a problem with the distributor, possibly the cap. You mentioned the distributor cap and rotor were recently replaced: These engines are very fussy when it comes to spark plugs, fuel pumps, and especially the distributor cap & rotor. All of them need to be AC Delco/Delphi if you want the engine to perform properly... yes, it does make a difference

 

Depends on how fancy you want to get. I found someone who was free for the night and have them turn the key off for me and I just pinched it shut and held it and watched. It's easier to do when there is extra hose to play with. And this is assuming you have a rubber line with the metal coupling at the end.

My mechanic when stressed with hard issues will splice a valve in with a bleed off in it so he can just turn the lever and then when he's done or found the problem isn't there will let the fuel bleed out and remove the splice cause at this point he already has to replace the lines so the old ones don't matter.

This is where I learned this method but I never went to that extreme. Seems like too much unless there is a lot of issues you're diagonosing at once. But if you went to that extreme to do that then you probably are replacing the lines anyways along with other things lol.

 

You can save yourself a bunch of grief by building one like this:



Connects inline at the fuel filter.