My truck ('90 3.9 V6) cuts out and stalls and dies while driving and idleing. I took off the air filter and started the engine while observing the injectors. The drivers side injector does not fire at all at idle, and when the gas pedal is floored, it spurts randomly, struggling to do so. My guess is the injector is bad? Or maybe dirty? I have a spare throttle bottle, and was wondering how hard is the process of swapping an injector out? Thanks for any help!

-Bryan

well if it is your injectors than that a easy fix take the fuel rail off and it takes some time but wiggle the injectors out. Put new o rings on then put some vasaline on the o rings it helps them go back in and it wont tear up the rings.

On the TBI system there should be a hold-down clamp for the injectors, remove it. You should be able to use a small screwdriver to pry them out.

Do I need to relieve the fuel pressure before removing the injector? If so, how do I do that? Thanks.

Look at the color of the wires that go to the injector/s. Dark green with a black tracer should be B+, the other is ground. Take the connector loose from the injector, use jumpers for B+ and ground. Run the ground to a chassis ground, hook the voltage jumper to the proper injector terminal, run the wire close to the battery, just touch the jumper to the positive battery post for a couple of seconds, do it a couple of times, that should energize the injector and relieve the fuel pressure. Usually after the vehicle sits overnite and the key isn't cycled, there isn't much pressure if any. It doesn't hurt to be safe, though.

I replaced the driver side injector and now the truck runs great! Thanks to all for the great help. Have a great day!