HELP! Truck wont start!

[christopherstone]

OK so I have had this 2000 Silverado 4.8L in my driveway for a couple days, been trying to figured out what the heck is wrong with it.

We put a new PCM in it and it still wont run.

It cranks, has spark, but I am assuming it is not getting fuel.

I sprayed carb cleaner into the throttle body and it starts up and runs for a couple seconds, then dies.

I noticed the oil pressure sensor was showing -15.4 psi...that correct... NEGATIVE 15.4

So I was wondering, did GM oncorporate a safetly feature into these that shuts off the fuel pump if the oil pressure is too low or the oil pressure sensor goes out?

I purged the fuel pressure relief valve and fuel comes out but it doesnt "spray", it kindof just dumps a little out then nothing after that..no pressure.

So I am assuming it is not on or is going out.

Also, I have been having trouble blowing the ECM B fuse on the truck... it will crank a bit then blow the fuse. I have went through a few boxes of fuses already. Here are the codes I am getting:

[PCM] P0102 - Mass Air Flow (MAF) Sensor Circuit Low Frequency (Immature)
[Brake] C0226 - LF Wheel Speed Signal Missing (History)
[Brake] C0222 - RF Wheel Speed Signal Missing (History)
[Unknown] B3148 - (History) (Immature)
[Unknown] U1255 - Class 2 Communication Malfunction (History) (Immature)
[Unknown] B2648 - (History) (Current) (Immature)
[Unknown] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[Restraints] U1000 - Class 2 Communication Malfunction (History) (Immature)
[Restraints] U1016 - Loss of Class 2 Communication with VCM (History) (Immature)
[Restraints] U1041 - Loss of EBCM Communication (History) (Immature)
[Restraints] U1096 - Loss of Communications with IPC (History) (Immature)
[Restraints] U1064 - Loss of Communications with DIM (History) (Immature)


Continuous Tests
Misfire: Complete
Fuel System: Complete
Comprehensive Component: Complete


Once Per Trip Tests
Catalyst: Incomplete
Heated Catalyst: n/a
Evaporative System: Incomplete
Secondary Air System: n/a
A/C System Refrigerant: n/a
Oxygen Sensor: Incomplete
Oxygen Sensor Heater: Incomplete
EGR System: Incomplete

The MAF code is OK..I unplugged it to prevent it from dumping even more fuel earlier....I was experimenting, wasnt sure if the plugs were fouled or not so I pulled the injector fuse and cranked it for a bit then unplugged the MAF and tried to crank. Finally I figured maybe check the fuel pressure relief valve and found that it wasnt getting much fuel at all. Thats when I sprayed the carb cleaner in the throttle body. Then it cranked and ran for a couple seconds.

Anyways...whats the deal with all these codes? I was driving when I got it but running very poorly. It was stumbling at idle and part throttle, but WOT was OK about 3000 rpms.

Another thing is the new PCM is from Autozone. I have had nothing but good luck with their PCMs in the past when one went south. Is this PCM bad? Or what could the reason be behind all those DTCs?

This is my sisters boyfriends truck and he just thought his alternator was going out and we ended up having all kinds of problems with it.

Any help at all would be greatly appreciated

thanks!

[christopherstone]

BTW I jut found out that the B2648 is a short to battery from the ambient light sensor.

I suspect this is what keeps blowing the fuses.

Now I just gotta figure out why it runs with the carb cleaner, but not on its own accord???

[kevmar]

have you done a crank relearn?

why did you do a install a new computer?

did you flash your old O/S into the new computer?

[christopherstone]

crank relearn has to be done with the truck running. Truck wont run.

Put the new computer cuz I opened the old one and it had small burn marks around a few of the items on the circuit board, truck was acting funny, throwing tons of codes.

I never flashed the truck, only scanned it. It is a customers car and he cannot afford to pay me to tune it anyways so I will not be flashing it. It is a new PCM. Didnt flash the old one either.

[christopherstone]

but yes the company I got the PCM from flashed the new one with the OS.

[C5 2000]

When you put the new PCM check and and see if you forget to put the earth wire back on? Also check your crank sensor and wires too...

[christopherstone]

you mean the ground? The PCM only had the two connectors...no ground..?

Crank sensor is fine. Ive checked and check and double triple checked all wires...all I could find was the bad oil pressure sensor behind the intake. ??

[LILFREDDIE]

What is your fuel pressure with a gauge?

[christopherstone]

What is your fuel pressure with a gauge?

Dont have a FP gauge...but the truck obviously doesnt have any pressure at all.

Dont worry about it guys. The guy is picking up the truck right now. He got impatient and wants to try to fix it himself lol.


Thanks though guys.