Chevrolet Repair: Chevy Tahoe, chevy tahoe, kind stranger

Question
My brother drove his Tahoe up from our hometown which is about 150 miles away from where I currently live, Tampa FL. On his way up here his trcuk was having trouble switing gears. When he arrived here, he turned off the truck and it would not start. He left back home in my car and left me his truck so that I can fix it. Well two days ago when he left, I tried to crank up the truck and I gave it a little bit of gas and it worked, it turned on. I drove it around and the truck had problems shifting into the passing gear, but did in fact shift. Today as I set fourth on my search for a mechanic, the truck fired up on my first attempt with no problems at all. As I drove around, I recieved a phone call from my mother, she asked me to fill the truck up with gas and put in a bottle of fuel injector cleaner as well. I did so and carried on with my search. Now the truck was having trouble switing into all the gears and finally stopped in the middle of trafic. A kind stranger helped me move the truck out into a near by gas station, he examined the truck poured some gas into a hole in the engine. After he did this he told me to try to turn the truck. It stayed on for a couple of seconds and then turned right back off. He said it was because of problems with the fuel pump. Another man examined about an hour later and told me the same. My brother told me a couple guys he knows, say it could be the fuel pump, it could be the fuel filter or both with the problem. What would you suggest the problem might be in my situation.

Answer
Hello Edgar,
It could very well be the fuel pump, or the filter.
The pump is inside the tank, and requires removal of the tank to change it.
I would not do that without some more tests, because if it isn't the pump, that is an awlful lot of work for nothing.

I suggest connecting a fuel pressure tester, and see what it says.
If the pump does not run at all, it could be the pump, but it could also be the fuse, relay, wire connection, engine control module, or ignition switch.

If the pump runs for two to three seconds after the key is turned to run, but the pressure is low, it could be the pump, filter, or pressure regulator, or a restricted line.

If the pump runs, and the pressure is good, it could be the injector fuse, the engine control module, or wire connections.

The gear switching problem could be tied to the engine power loss, or it could be a separate problem, but you need the truck running to check it.

If you want to just guess, and try things, at least see if you can hear the pump running in the tank, and if it is, change the filter. it is under the drivers seat area, bolted to the frame.

Van