First time poster, but I have been searching the forums for some time to find an answer to my Grandfather's truck's issues. The truck is low miles and does not get ran much. It has the factory v6, no modifications.
It all started this spring when he went to start it, but it wouldn't start. It turned over fine, but did not run. He tried using starting fluid, and that got it going, but he had to keep hit foot on the gas to keep it going. After it would warm up, he could get it to idle. If he would try to put it in gear, it would immediately die. I checked the fuel pressure, and it would go to about 5psi when you would prime the pump, but as soon as you would stop priming, the pump would not hold any pressure. When cranking, the injectors would spit the little bit of fuel from when the pump primed, but it would not be enough to fire. It would then hit 0psi and stay there when cranking over. If you would use gas or starting fluid to get it started, the pump would maintain no more than 8psi, and you would have to keep your foot on the gas.
I replaced the fuel filter and all the fuel lines, and made sure the new ones were not plugged. I also replaced the fuel pump with a new one since it was maintaining low pressure and because I got one dirt cheap. Now the truck is maintaining proper pressure and the injectors are spraying like they should, but it still will not start without adding gas, or idle, once started, unless you keep your foot on the gas.
Any suggestions? Maybe throttle position sensor? or even a combination of things? Any help would be appreciated!! Thanks!!

 

It sounds like it may be way too lean of a mixture, which could be caused by several things, but if memory serves, the pump moved fuel to a chamber mounted on the carb. The engine uses what it needs from here, but the fuel pump keeps supplying fuel as long as the vehicle is on. Excess is returned to the tank via a pipe. This tank could be faulty. There is a float inside it, these are made of a material, though i forgot its name, it has a tendency to stop working, it gets saturated with fuel, or dries out and crumbles. Check this device, again, i dont know the name of it, but it should be right in line with the fuel line, mounted to the carb. Just follow the pipes.

 

The engine is fuel injected, so it would not have a float like a carb, would it? The plugs did not have any signs of detonation, but they did appear like it was running lean before I replaced the fuel pump. Thanks for the suggestions, keep them coming!!

 

I will be looking at the truck again today, so any help would be appreciated!!

 

if it is an 1988, it will be SEMI computer controlled, but there will still be a carb. If I remember correctly, the computer only controls timing and emissions in these years. Like mulder25 said, check the carb floats, they are likely bad

 

I wish it were such an easy fix, but like I posted previously, the truck is fuel injected; no carb to check the floats.

 

Sounds like the IAC (Idol air controller) Will be on the side of the throttle body.