So my truck has driven me crazy with frustration. It's a 5.8l and I don't work on fuel injected engines really, so I don't know where to start. I have taken it to a mechanic many times and he has never been able to fix the problem.

Most of the time, except for more recently, the truck will start fine, run fine. You can hear the fuel pump start for a few seconds starting it each time. Many times however when you try and start the truck you can hear the fuel pump run and it won't stop. Truck won't start either, just turns over and over. Rarely you won't hear the fuel pump, truck won't start. And if you are really unlucky, you will just be driving along like you always do and truck will die or nearly die. It will stay running, but with barely enough power to reach 20mph in about 3 minutes whether you are light on the gas or hard on it.

It is really hard for the mechanic becuase everytime we take it there it is running fine. The doesnt give any codes either (all pass). So I don't know what to do... Should I just wait for it to happen again and check electrical connections? If so, which ones? Or should I just bite the bullet and replace the fuel pump?

Thanks a bunch for your help, I hope this isn't some really common problem that I just haven't found the answer to.

Edit: Things that have been raplaced: Fuel filter, EGR valve/sensor.

 

Replace the PCM.

 

Ok, so I went through all the ignition system checks from the Haynes manual with a voltmeter/ohm meter. The only problem I found was that the SPOUT circuit was outputting like 25 AC volts (the book said it should have been between 3 and 8.5 AC volts). I took out the disconnect and tried again, same thing on the PCM side as before, and like 12AC volts on the ICM side. I don't know what this means, except that maybe the PCM needs to be replaced. Would this cause the problems like I said above?

Thanks for the comment subford, I appreciate the advice but maybe you could give me a little more info? I like to know why things work/don't work. Thanks.

Also, I hear a sound after shutting the engine off from around the fuel rail/manifold area. Like a slow releasing pressure, takes about 10 seconds to slow/stop. Is this normal? What is it?

 

Sorry, I did not have much time and had to go someplace yesterday.

The reason I said replace the PCM is any time the fuel pumps do stop running with the key on and engine off it is a bad PCM if the fuel pump relay is OK.
Sounds like your fuel pump relay is OK.
Also the non-starting with the fuel pumps running and then it fixes itself for awhile says you have bad caps inside the PCM.

The SPOUT information comes from the PCM only, I have no idea what you are checking with the AC readings. I do not use Haynes manuals and I do not know what they came up with.
To check the SPOUT put a timing light on the engine and unplug and plug the SPOUT jumper back in with the engine running. If your timing moves then the SPOUT is working.

The sound after you shut the engine off is either the A/C system equalizing (normal) or you have a bad fuel pressure regulator (not normal).
Can also be compression leaking past the rings.