If I didn't have to finish rewiring a Hot Rod today, I would be online to help you to at least check the fuel delivery system.

I hear you on that one was a long 12 hours at work and I didn't want to get out of bed!! But any way...

TEST 1:

I want you to remove power by disconnecting the negative terminal on the battery for 30 seconds to one minute.

Done

Making sure all CKTS are <OFF>, reconnect the battery.

Done

Get in the truck and turn to <KEY ON> DO NOT START IT at this time.

Note gauge activity. Power and movement and any anomalies. (flashing ODO etc)

Oil, Temp, Alternator gauges power on move to base settings. No movement Fuel gauge or Tach. Idiot lights come on and off ABS and Airbag light come back on. Odometer begins to flash...

<START> the vehicle. (Try to anyways)

Does it start? Y / N? Not turn over but, actually start up.

YES

Does it run for x- minutes Y / N?

NO

Does it run for 3-seconds and shut down? Y / N

Maybe 3 seconds

Do you have any input at the gauges during this time Y / N?

Oil, Temp, Alternator gauges power on move to base settings. No movement Fuel gauge or Tach.

TEST 2:

Now, again, disconnect the battery and wait.

Done

Reconnect and, this time, turn the key to <START / RUN>

Does it run for X-minutes Y / N?

NO

Does it run for 3 seconds Y / N?

Same Possibly 3 seconds

Thanks TTYL

 

Hello.

I noted that in both tests- you've got nothing and, it doesn't run and, in both tests, the ODO flashes like a streaker running down Times Square.

I'm now going over the system and, how it works, normally, when you turn the key to <ON> (KEY ON MODE), it's supposed to activate the fuel system for 3 seconds. During this KEY ON event, you should hear the fuel pump running for ~ 3 seconds.

I would like you to verify whether or not you can hear or feel the fuel pump running or not by placing a tube to your ear from the PUMP / TANK up to your ear in the cab while turning the key to <ON>.

If the answer is YES: this means that the ASD relay is indeed being energized for three seconds. This means that the PCM is working to some degree and not totally dead.

We are primarily concerned with two modes of PCM operation and they are: KEY ON MODE and START UP MODE

FUNCTION:


KEY <ON> MODE:

- PCM pre-positions the idle air controller motor

- PCM determines atmospheric pressure from MAP sensor

- PCM monitors engine coolant temp

- PCM monitors Intake air temp

- TPS is monitored

- ASD relay is energized for 3 seconds by the PCM

- Fuel Pump is energized for 3 seconds through the fuel pump relay for 3 seconds

- O2 sensor heater element is energized via ASD relay


So, this is why I had asked how long it ran for in seconds. Now, what we need to know is: if the fuel pump runs for 3-seconds, we know that the ASD relay is getting power and being energized by the PCM for 3-seconds which means that the PCM is NOT DEAD.

I know this is a slow process vs. if I was there with you going through each test in quick succession but, it's the only way to factor out possible failure modes and avoid paying money for a new PCM when the root problem may lie somewhere else such as in a spent fuel pump.

The next mode is ENGINE START UP MODE

This is open loop mode and, this is the sequence of events at the PCM

PCM receives input from:

-battery voltage

-ECT (coolant temp sensor)

-CKPS (crankshaft position sensor)

-IAT (intake manifold air temp sensor)

-MAP (manifold absolute sensor)

-TPS (throttle position sensor)

-Starter motor relay

-CPS (camshaft position sensor)

FUNCTION:

The PCM monitors the CKPS and, if it does not receive a signal within 3-seconds of cranking the engine, it shuts down the EFI system.

The FUEL PUMP is activated through it's relay in the PDC.

Voltage is applied to the injectors with the ASD relay via the PCM. The PCM will then control the injector sequence and pulse width by turning the GROUND CKT to each injector ON / OFF. The PCM will also determine the proper ignition timing according to input received from the CKPS.

To fully understand what happens when you start your truck is important because, if you have an understanding of the system level function, it makes it easier to know where to start looking and testing.

So, somewhere, in either key <ON> mode (where I think the fault lies) or <START> mode, we have a problem and, if during the 3-seconds you hear ZIP at the pump, there's a possibility that the PCM IS NOT energizing the ASD relay which leads to the conclusion that either the PCM is dead or the fuel pump may be dead or, a automatic shutdown event has been triggered and stored.

Listen for the fuel pump kicking on and TIME it. Listen for it spinning, whirring etc and report back.

CM

 

So, how's it going? Listen, there's one simple thing that you need to check as well and, that's the connector at the PDC that has one bolt holding it on. Remove power, remove the bolt, clean the contacts, apply dielectric grease and plug it back in and screw it down. On those, this was another problem for a NO CLUSTER condition: However, a NO BUS signal is usually displayed.

Let me know the results of the key on test.

CM

 

I would like you to verify whether or not you can hear or feel the fuel pump running or not by placing a tube to your ear from the PUMP / TANK up to your ear in the cab while turning the key to <ON>.

If the answer is YES: this means that the ASD relay is indeed being energized for three seconds. This means that the PCM is working to some degree and not totally dead.

I had my GF turn the key to on and the fuel pump did indeed come alive for maybe 2 to 3 seconds

So, somewhere, in either key <ON> mode (where I think the fault lies) or <START> mode, we have a problem and, if during the 3-seconds you hear ZIP at the pump, there's a possibility that the PCM IS NOT energizing the ASD relay which leads to the conclusion that either the PCM is dead or the fuel pump may be dead or, a automatic shutdown event has been triggered and stored.

Listen for the fuel pump kicking on and TIME it. Listen for it spinning, whirring etc and report back.

I had her attempt to start the truck this time and once again the fuel pump came alive for 2 to 3 seconds. Then again for approximately 2 to 3 more seconds before the engine died...

So, how's it going? Listen, there's one simple thing that you need to check as well and, that's the connector at the PDC that has one bolt holding it on. Remove power, remove the bolt, clean the contacts, apply dielectric grease and plug it back in and screw it down. On those, this was another problem for a NO CLUSTER condition: However, a NO BUS signal is usually displayed.

I had already loosened the connector and reseated it but did not completely removed it. I will try cleaning it and reseating today... Thanks

 

Hey, looks like you're gettin some good help, but I thought I would just toss an idea out there...

Have you tried reseting the computer? I had some problems with sputtering and staying fired up, and my GF's bro who is an engineer for Chevron told me a way of doin it. It's kinda Hokey Pokey'ish, but hey, it worked.

Unhook both battery cables and touch them together for 30 sec. Then leave them apart, not touching any metal, for 15 min. After that touch them back together for another 30 sec and hook them back up. Turn the key to <ON> and you should be all set for the reset. Timing is important so try to stay close to the times.

Try it if you want to cant get much worse from the sound of it...

 

Normally, when removing power from the PCM such as when disconnecting NEG -) all power is drained after 30 seconds and the memory is wiped / cleared. Power keeps the ram alive.

I had him reset the PCM twice already during testing with this method.

I don't advocate that method of SHORTING OUT THE HOT TO GROUND. What can happen is an ARC at time of dead shorting to ground THUS INDUCING a voltage spike thus killing the PCM down to component level and / or killing the EEPROM chips thus not allowing it to read the program thus making it impossible to reflash thus requiring a NEW PCM. What your doing there is going from a fully charged state to a VIOLENT discharge in a matter of milliseconds. This is hard on the caps and, doing that will weaken them internally as well as throwing the amount of charge that they can hold so, the next time you fire up the PCM, the cap is not able to hold charge long enough thus throwing the supply out of whack thus the rest of the CKT will not function properly as well as causing latent and intermittent problems that are very hard to diagnose.

The safer method to doing that (this is a MUST) is to place a 1M R in between the leads to SHUNT it to ground slowly and gently.

But, that method does not need to be performed because, once power is removed, all memory of all data, stored codes, fault codes etc, are wiped clear thus resetting all the data values to zero.*

*There are SOME fault codes that are exempt from this and, only a special tool such as a DART or OBDIII tool can extract them / clear them. Such is the case with ABS fault codes. Those must be cleared with a tool.

CM

 

Ok, that enough information to come to a conclusion as to what the possible root cause is. Your PCM is NOT DEAD for, if it were, it would NOT START nor would you hear the FUEL PUMP start up.

-rules out the pump

-rules out the PCM

So, again, KEY ON MODE: we hear the pump. It's getting power. THE PCM is energizing the ASD RELAY which, in turn is powering on the FUEL PUMP RELAY which is sending voltage to the pump motor thus spinning it.

Since it started, we know that the PCM is indeed powering EFI system for 3 seconds. That means that the PCM program level is running and COM is established with the EFI system.

We also know that at one point, it did run and, it ran rough. Then, things progressively got worse to where it was almost stalling out, then, you'd rev it and it would be fine. Until, one morning where it finally called it quits and, most likely after it went into LIMP HOME MODE- guessing that's what happened and, then it set the auto shutdown mode which, cuts all power so, it wipes out any fault codes that may have been set thus not being able to retrieve them due to having a COMM failure which, was indicated by the FLASHING ODO.

This can be a few things but, at least we know which direction to start probing.

CHECK THE PDC CONNECTOR. You may have corrosion inside thus inducing high resistance thus dropping voltage across the pins thus inducing a low voltage condition thus leading to a NO START condition due to the ASD relay being tripped after the PCM SENSE "VOLTAGE TOO LOW". RETEST immediately after cleaning.

EDIT: Also, I did not see the results of a voltage test that I had asked you to perform. I want you to place a meter across the battery and run it in the window facing you. Turn the lights to ON and HIT THE STARTER. I didn't see the results of that but rather, a test of just putting the lights on and the recorded voltage. I need to see what the BAT is doing at time of hitting the starter with a load on it.


VOLTAGE DROP DOWN TEST

-meter across BAT

----turn lights <ON>

------place meter in the window facing the driver seat or, have the GF hit it while you read it.

---------HIT THE STARTER (turn it over)

------------NOTE VOLTAGE DROP (it will NOT be 12.5 nominal- it will drop and, I need the voltage readout e.g. 9.5 V)

<END>

CKPS: CHECK

-check the connector pins on BOTH sides

---check the leads for damage

------check the face of the connector for debris and / or damage

---------R&R as necessary (GO WITH OEM ONLY)

<END>

CPS: CHECK

-perform the exact same examination as noted above for CKPS

<END>


Start with those and report back when you can.

CM

 

Try checking both the crank and cam sensors,the crank sensor is located on the passenger side at the side of the bell housing just behind the head.The cam sensor is under the distributor cap.

 

The abbreviation for those is:

CKPS: Crankshaft Position Sensor

CPS: Camshaft Position Sensor


Those were part of my test plan as noted above.

CM

 

Damn time to get back to work on this!! Sorry was away doing some family stuff and family time!! I'm back and will get back to the grind tomorrow. Thanks for everyone's suggestions I will keep you posted... Thanks again!!