I still havent been able to figure out whats going on with my truck. After putting on a new fuel pump, I cant get the truck to run more than 5 sec., after it being hard to start in the first place. I had the battery unhooked for about 3 weeks, and im wondering if my pcm needs to be reprogrammed due to the battery and the addition of a new pump.

Already cleaned the injectors

Also before (when my truck ran) i noticed that when my battery dies or goes low, after i jump off my truck it doesnt want to run idle and stalls out at stops and turns, but after about 3 or 4 days of this it will stop and run perfectly fine again.

Any help would be appreciated Thnx

 

Make sure the battery is fully charged, and the alternator is working correctly.

Pull the throttle body, and clean the IAC pintle, and the passage in the TB.

Verify your throttle position sensor is working correctly.

Reset the PCM, see how it feels.

 

I have no idea what the IAC pintle is or what the throttle position sensor looks like. Is there another way to reset the pcm other than taking off the battery cable? (guess imma old skool carburetor guy) lol

 

IAC=Idle Air Control. Its on the back of the throttle body. That's what regulates air flow when the throttle is closed. (and thereby controls idle speed)

TPS is on the drivers side of the throttle body, and clues in the PCM to how hard you are stepping on the accelerator.

Disconnecting the battery is one of the better ways to reset the PCM.

 

Thanx im sure i can find all this, and the battery cable is unhooked as we speak. I didnt really know when i was gonna work on it again. So I unhooked it so that the battery wouldnt die

 

That'll work. Have a look, see what ya find, let us know.

 

While there's always the possibility of a failure at the PCM level, it's also quite possible there's a short in the system thus, the reason for draining the battery down.

The fact is: you could leave the battery out for ten years and it would not require you to reprogram the PCM.


If you're getting exactly five seconds and not three seconds, then, one can say that it's not due to the PCM going into Automatic Shutdown Mode or, that the supply has been shorted to failsafe event / shutdown of the PCM itself.

I'll bet that either you've got a MAP sensor issue and, the reason I say this is this: when the map sensor craps out, it just won't run at all. The timing will feel like it's jacked, it won't get the correct amount of fuel and, it will not run.

Again, this is based on your comment of "FIVE SECONDS".

The TPS sensor when it goes out, can induce a high or low voltage at PCM input thus, the PCM reads this as either a lot of air is coming in or not thus, the program dumps a ton of fuel or leans it out based on the voltage present at input. Remembering that the TPS sensor is reading the position of the throttle plate and, throttle plate position directly correlates to the amount of air coming into the intake.

If the IAC valve is stuck shut, it starves for air thus stalls out. If one depresses the accelerator slightly, and, the engine picks back up and runs fine, yes, it's most likely due to an IAC motor assembly gone south.

If the CPS (CAM) sensor goes out, it may create a lopsided pulse thus, the timing will be off.

If the CKPS (CRANK) sensor goes out, same thing will occur if it's partially working.

If either one fails completely, the PCM will not allow the engine to start at all. So, since you're able to get it started, and, it runs for five seconds, chances are, you've got either a MAP sensor out of whack, TPS is way off, or, the IAC valve is totally choked.

But, you may also have a fault at the coil level as well. It may not be putting out the proper amount of voltage to the dizzy rotor thus, not enough juice to ignite the fuel mixture 100% all of the time. It also may be due to something as simple as a bad dist cap or rotor thus, not conducting 100%. It also may be a bad coil wire that supplies voltage to the rotor. The list goes on for a while here.

There's also a lot more that would also induce the same type of symptoms that involve the FUEL DELIVERY SYSTEM such as, frozen lines due to moisture from sitting to, a failure at the wiring harness that feeds the FUEL PUMP. One would have to measure voltage at the pump with the connector installed and, under load. I have a process for this so, if you're going to do it and, you're looking for a process on how to do so, let me know.

And, yes, if the PCM coil driver circuit or, the ground circuit has high resistance at the PCM level, or, there's an issue in your charging circuit at the PCM level, or, if the injector driver circuit has an issue at the PCM level, yes, the PCM would need to be replaced. But, determining that is a bit of work but, doable if one has the right tools, the time, a warm garage and, some know how.

Good luck and, start testing things out one at a time until you've found the root cause.

Start with the simplest of tasks first and go from there.

Regards,

CM