Anyone have Experience with 5.7L GM Vortec?

[HHR]

My Grandfather has a 1997 GMC Sierra 1500 5.7L in mint condition with around 65,000 miles. Truck has been running very well since we replaced the Mass Airflow Sensor last month (Had stalled out/flooded throwing P0103 code).
After sitting for three days in the garage, he went out to start the truck and it cranks normally but does not fire/start.
We did some simple testing and it is getting no fuel or spark and neither my scan tool or code reader will communicate with the truck. Fuel pump does not run unless relay is bypassed (computer not sending any voltage to relay coil terminal). Checked for spark at #1 plug wire and at coil.
Does anyone haven any suggestions as to what would cause no spark and fuel at the same time? PCM?

 

[MickeyDBC]

Crank position sensor?

 

[SimS]

Google is your friend:

P0103 - Mass or Volume Air Flow Circuit High Input Possible causes Faulty mass air flow sensor Intake air leaks Dirty mass air flow sensor Dirty mass air filter Mass air flow sensor harness is open or shorted Mass air flow sensor circuit poor electrical connection

Read more: P3 Mass or Volume Air Flow Circuit High Input

 

[HHR]

Google is your friend:

P0103 - Mass or Volume Air Flow Circuit High Input Possible causes Faulty mass air flow sensor Intake air leaks Dirty mass air flow sensor Dirty mass air filter Mass air flow sensor harness is open or shorted Mass air flow sensor circuit poor electrical connection

Read more: P�1�3 Mass or Volume Air Flow Circuit High Input

I had added the MAF repair to the post for context. This new problem appears unrelated.

 

[JohnBuffaloMN]

My Grandfather has a 1997 GMC Sierra 1500 5.7L in mint condition with around 65,000 miles. Truck has been running very well since we replaced the Mass Airflow Sensor last month (Had stalled out/flooded throwing P0103 code).
After sitting for three days in the garage, he went out to start the truck and it cranks normally but does not fire/start.
We did some simple testing and it is getting no fuel or spark and neither my scan tool or code reader will communicate with the truck. Fuel pump does not run unless relay is bypassed (computer not sending any voltage to relay coil terminal). Checked for spark at #1 plug wire and at coil.
Does anyone haven any suggestions as to what would cause no spark and fuel at the same time? PCM?

I'd start with electrical - fuses, mice chewed through wires (hope not), etc.. since you're not able to get a connection to the computer with your scanner. The Internet is your friend - if you are lucky someone else has had this problem and was nice enough to post about it.

I got a FREE 1999 F150 that had been very well cared for. It had already been to the shop costing the owner over $2,000.00 for them trying to figure out why the vehicle would run great only to stall out intermittently driving down the highway, requiring turning ignition off/on to restart. That was one clue. It took me a week searching Internet, then messing around with overdrive solenoids and dash wiring until one day I found a post about my problem. It was coilovers that were the problem - when one coil would fault it would simply register in the computer - when two faulted simultaneously the computer itself would fault and shut down the engine! The solution was to replace the coil overs that were factory originals (about 190K miles). Those coils cost me $200.00 for 10 (anyone need a couple coil overs for an F150?).

 

[Zick]

My Grandfather has a 1997 GMC Sierra 1500 5.7L in mint condition with around 65,000 miles. Truck has been running very well since we replaced the Mass Airflow Sensor last month (Had stalled out/flooded throwing P0103 code).
After sitting for three days in the garage, he went out to start the truck and it cranks normally but does not fire/start.
We did some simple testing and it is getting no fuel or spark and neither my scan tool or code reader will communicate with the truck. Fuel pump does not run unless relay is bypassed (computer not sending any voltage to relay coil terminal). Checked for spark at #1 plug wire and at coil.
Does anyone haven any suggestions as to what would cause no spark and fuel at the same time? PCM?

If you can't get any readings from the OBD connection, check the cigarette light fuse. Usually they are the same fuse.

 

[HHR]

If you can't get any readings from the OBD connection, check the cigarette light fuse. Usually they are the same fuse.

All fuses test good. The OBD port has 12V power on pin 16, which turns on my scanner, but it simply can稚 establish a connection on the data line. The same tool worked perfectly on this truck when we had the MAF problem only 3 weeks ago.

 

[timswi]

Might be an outlier, but once I couldn't get an ODB2 signal and I disconnected the battery for about 45 minutes and it worked after re-connecting. Possible coincidence --dunno.

 

[HHR]

Might be an outlier, but once I couldn't get an ODB2 signal and I disconnected the battery for about 45 minutes and it worked after re-connecting. Possible coincidence --dunno.

Tried that also. Today we tested ignition switch and tried new crank position sensor with no improvement. Had ignition control module tested (good) also. That module should be a pulse from PCM on white wire, but instead, it痴 grounded out inside the PCM continuously. Have decided to order a pre-programmed PCM.

 

[Stimw]

I don't remember the years but they had chipped keys and if a non-chip key was used it shut everything down.
Do you have more than one key?