I just picked up a 1993 Dakota V8 5.2L automatic from a friend of mine for $1000. It was sitting for over a year. Tried to get it inspected here in Texas and it failed the emissions at idle speed ( Hydrocarbon levels at 600+ at idle ) although it passed at 2500 rpms. It had a miss in it which I didn't notice at first, which I fixed by doing a tune up (oil change, new plugs and wires, air, fuel and oil filters.) I also replaced the EGR valve as well as the IAC valve.

It is running a bit better, but I believe I am experiencing low fuel pressure in it now. Hooked up a gauge and it's getting between 34 - 40 psi while running. It is idling really low at 200-300 RPMs. It drops pretty quickly to around 20 psi or lower with the engine off. It does, however, start immediately when turning the ignition. I tested the resistance of each injector, they all came up around 14.5 ohms so I believe they are all working properly. There doesn't seem to be any visible fuel leaks on the injectors or fuel rails and I pulled the vacuum hose from the fuel pressure regulator while it was running and left it off for about 5 minutes, but didn't notice any fuel coming out of the regulator which would indicate a busted diaphragm. I also noticed that there was no change in the idle when pulling the vacuum line from the regulator. BTW, it is not throwing any codes whatsoever when doing the key dance.

Does this sound like a possible issue with the fuel pump as opposed to the fuel pressure regulator? When turning the ignition key you can easily hear the pump priming the fuel system so it is definitely alive, there just seems to be slightly low pressure in the system. I've already spent quite a bit of money trying to get it to run correctly so I can get it to pass when I get it re-inspected, but I'm not sure I can afford the $150+ for a new fuel pump on this baby. If it is the fuel pump, would it be possible to install an in-line fuel pump after the fuel filter to increase fuel pressure without having to pull the bed off and replace the in-tank pump?

 

That sounds good for the pressure, but how is the pressure while driving that is when it is necessary to test.

 

How exactly would I go about reading the tester gauge while driving it?

Just replaced the TPS. Also removed all 8 of the injectors and cleaned them thoroughly with carburetor cleaner. There appeared to be a very small amount of tiny black chunky stuff in the screens before cleaning them. Also replaced the O-ring on the injectors before re-installing them. I was experiencing stalling at stops and in reverse before occasionally, but now that has stopped. I am still getting some really low RPMs in gear though, like between 200-300 RPMs. Slapped the fuel pressure test gauge on again and tested it at idle again. I am getting a pretty consistent 35psi at idle, and around 42psi upon removing the vacuum line on the fuel pressure regulator. Unfortunately I haven't yet figured out how to check the gauges while driving. Only way I can figure to do that is have someone drive it with the hood up while I ride in the engine compartment, lol!