1999 Pontiac Grand Prix Hard to start, but runs after start

Tiny
JCNAVALACADEMY
  • MEMBER
  • 1999 PONTIAC GRAND PRIX
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 163,000 MILES
My 99 Grand Prix GTP (3.8 Supercharged) is difficult to start. I have to keep cranking on it before it tries to fire and even then I have to be quick on the throttle to keep it running. When starting, I will turn on the key and listen for the fuel pump to stop running before I attempt to start it. My service engine light is not on, but I'm not sure if it may not be burnt out. It doesn't run super smooth after being started. I just don't even know where to begin looking for the problem.
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Saturday, March 27th, 2010 AT 12:33 PM

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Tiny
MMPRINCE4000
  • EXPERT
Check engine light should illuminate when key is on, if not it is burnt out.

Take to autoparts store and have PCM scanned for codes, this is a good place to start.
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Sunday, March 28th, 2010 AT 8:31 AM
Tiny
JCNAVALACADEMY
  • MEMBER
I had the computer scanned for codes and my fuel pressure checked. Fuel pressure built to 50 psi and held. The codes that I got were:

P0650 Malfunction Indicator Light Control Circuit
P1374 3x Reference Circuit

I have been searching to find what these codes actually mean or some troubleshooting guidance.
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Monday, March 29th, 2010 AT 8:56 PM
Tiny
MMPRINCE4000
  • EXPERT
The 3X reference signal is produced by the ignition control module (ICM). The ICM calculates the 3X reference signal by dividing the crankshaft position (CKP) sensor 18X pulses by 3. This calculation is performed while the engine is running, and while the CKP sync pulses are being received. The powertrain control module (PCM) uses the following information:

The 3X reference signal in order to calculate the engine RPM, and the CKP at engine speeds above 1,200 RPM
The pulses on the circuit in order to initiate injector pulses
A constant monitoring of the number of pulses on the 3X reference circuit
A comparison to the number of 3X reference pulses to the number of 18 X reference pulses and CAM signal pulses being received
If the PCM receives an incorrect number of pulses on the 3X reference circuit, DTC P1374 will set and the PCM will use the 18X reference signal circuit for fuel and ignition control. The engine will continue to start and run using the 18X reference and camshaft position (CMP) PCM input signals only.

This would have to be checked by GM or competent garage as P1xxx codes are manufacturer specific.

P0xxx codes are generic OBDII codes applicable to all OBDII PCM's.
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Tuesday, March 30th, 2010 AT 9:10 AM

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