Jimmy not running, starting

I have a 2000 Jimmy that I have been having starting, running problems with for the last month. It began with it dying as I was coming to a stop and then would not start again. But after an hour or so, it would start and run fine. The first time, they replaced the fuel pump. The second time they told me it was overheating due to a crack in the radiator and replaced it. The third time, they adjusted the throttle plate and said there was a clogged vent line and cleaned it. Yesterday, after running fine for several days, after coming back from shopping, it would not start at all even after a couple of hours and had to have it towed. But of course today, it started fine.

The only way I can describe the problem is it acts like it has run out of gas and/or is starving for gas. The service engine light stays on and also the fuel gauge is no longer working. The problem seems to surface on very humid days.

Get a fuel pressure gauge on it and check fuel pressure when it quits or no start.
If the gauge and fuel pumps is acting up also check the grounds on them.
Any codes or check engine lights?
4.3 V6 right?

The only true test on a fuel pump is to check the direct fuel pressure from fuel pump.
A quick test is to block off the return line and see if fuel pressure comes up to 75-85 lbs.
But do not run the pump at full pressure very long.
Also when testing fuel pump and pressure you need to tape a gauge to outside windshield or outside mirror and drive it on the road for 20 -30 minutes
until the pump gets has run a while to check for a pump fading out after hot.

Hard to start cold or hot and fuel pressure testing guide lines.
Check cold start fuel pressure.
Check engine running fuel pressure.
Check engine running on the road fuel pressure.
Then shut it off and watch for fast leak down.
Pinch off at rubber part or block off return line and check full pressure.
If pump has full pressure with return line blocked and low pressure without it blocked most usually the fuel pressure regulator is leaking or not holding pressure.
Later V6 and V8 gm engines should have 60-66 fuel pressure.
Cold start should be 64-65 lbs of pressure.
If you do not have full fuel pressure on a cold start the injectors will not squirt fuel.
Do not leave home without it.
Engine running should be 60-66 lbs pressure depending on engine load.
Full pressure with return pinched off should be 75-85 or more.
And if it has a fast leak down after shut off you have a leak in system.
Post back fuel pressure readings.

MT

I have a 1999 S-10 with the 4.3 engine. I also had the fuel pump replaced.
Do you hear the fuel pump whine when you shut off the engine after it dies?
My problem was the ground right from the tank. Spliced the wires and screwed it right into the frame beside the tank. Hasn't died yet and it's been over 4 months now.

I have a 1999 S-10 with the 4.3 engine. I also had the fuel pump replaced.
Do you hear the fuel pump whine when you shut off the engine after it dies?
My problem was the ground right from the tank. Spliced the wires and screwed it right into the frame beside the tank. Hasn't died yet and it's been over 4 months now.

Is it supposed to whine? Or not supposed to whine? I replaced my fuel pump recently and am having the same problem as gama.

Welcome to AF
They are like kids some whine and some do not.
But if you can hear them running and or whining it is good if they are pumping the correct pressure.
Run the pressure test as outlined.
If you need help on yours start a New thread and someone will help you.
Saves hyjacking another post.
MT