I read through all the threads i found, just wanted explain my exact problem. Have a 97 12v, after sitting for about 2 days, you go to start the truck, it starts fine, runs for about 20 seconds, then sputters and stalls, then you have to crank the heck out of it to get it to start again. Customer says "if you press the pedal before it stalls, it will not stall and will be fine" I glanced at the lines under the hood and they look fairly new, but i could only see 1, we pressurized the tank, and didnt hear any leaks or see any fuel. any clues? thx

 

I would start with the fuel filter, then fuel leak on the return line at the back of the head.

 

Check fuel solenoid, that it is working correctly. Like J-fox said, fuel filter, also check pre-filter. Make sure that Idle is set hi enough.

 

Check fuel supply lines that supply fuel to lift pump, if not replaced they will always be found cracked and leaking fuel. The return line also which is just behind fuel filter housing. Replace both of them, and adjust idle RPM, set when engine is operating temp in gear with a/c on, 750 RPM. It is not easy to get at these fuel lines best done when vehicle is on rack. 10mm screw rear of injection pump loosen lock nut first, then turn botton screw clockwise to increase rpm. Tighten lock nut while holding adjusting screw so it doesn't turn. May take several tries to get it set to correct RPM. Also check to see if Safety Recall B15 has been done, read attached PDF file. Good Luck

 

i just went through this after all the checking and re checking for weeks . it turned out to be the filter drain on the side of the filter would not leak under pressure just the vacuum pulled from the fuel line to tank was enough

 

the fuel heater can leak where the electrical plug in is. Seen this several times, can be hard to find. Need to put air pressure into the tank, not much. Make sure to put a vise grip on the return line, this makes it easier to spot leak on lift pump side.

 

I would suspect the electrical connection from the fuel heater. Unplug the heater connector and fill the plug with grease and then replug it. If the problem goes away, you have a leaking insulator on the heater.

However, if it only does this when down below 3/4 tank of fuel, it will be pick-up tube in the fuel tank. They crack and start sucking air when the fuel level is down below the crack.

Another option is the flexible suction line on top of the fuel tank that routes to the hard lines on the frame. I have lost count of how many times I have had to change the tank to frame lines because the owner always replaced the obvious lines to the engine, but forgot that there were two more on top of the tank.