Truck Repair: starting problem, crankshaft position sensor, fuel pressure regulator

Question
QUESTION: I have a 97 GM hd3500 1 ton. 7.4 litre. auto 2 wheel drive.Have a starting problem. It starts great in the morning.If stopped at ant time after that & restarted within 1/2 hr, it will start great, BUT, if it sits any longer than 1/2 hr. the motor will have to turn over for 15 - 20 sec. before it will start. When it starts then it smells like it was flooded. I have changed the injectors, & the fuel pressure regulator with no luck on fixing the problem.Fuel pump was changed a couple years ago. I have no other problems with the truck running. It runs great all the time except for this starting ghost.Could the fuel pump be the problem even though it seems to run proper? No one seems to know how to fix it. I can always use more advice. THANKS

ANSWER: Hi Dean,
I did some searching and found this TSB at http://oursuv.com/oldsubforum/Forum/suvsuburban0102/messages/3814.html.
check it out, it sounds like the crankshaft position sensor may be hooped. It seems like a common problem with these engines.

Good luck,

Matt

---------- FOLLOW-UP ----------

QUESTION: I cannot get this link to open. What does this sensor do & why would it cause the problem. Thanks again.DEAN

Answer
hey,
I copied the TSB for ya:

Posted by Jay P on April 03, 02 at 07:52:27:

In Reply to: 99 2500 7.4L TSB for poor warm start? posted by Jeff Jones on April 03, 02 at 05:30:49:

Bulletin No.: 00-06-04-014

Date: April, 2000

TECHNICAL

Subject:
No, Hard, or Slow Start, Backfire or "Kickback" During
Crank/Start, "Grinding" or Unusual Noises During Crank, DTC P0338
(Replace Crankshaft Position Sensor)

Models:
1999-2000 Cadillac Escalade
1995-2000 Chevrolet and GMC SIT Models
1996-2000 Chevrolet and GMC C/K, M/L, G, P Models
1996-2000 Oldsmobile Bravada
with 4.3 L, 5.0 L, 5.7 L or 7.4 L Engine
(VINs W, X, M, R, J RPOs L35, LF6, L30, L31, L29)

Condition:
Some customers may comment on one or more of the following conditions:

^ Backfire during crank/start
^ "Kickback" during crank/start
^ "No" start
^ "Slow" or "hard" start/crank
^ "Grinding" or unusual noises during crank/start
^ Cracked or broken engine block at the starter boss
^ Broken starter drive housing
^ Broken starter ring gear on flywheel
^ Any combination of the above

Cause:
A condition may exist that allows the crankshaft position sensor to command up to 50 extra degrees of spark advance during engine cranking only. This in turn exposes the engine to higher than normal cylinder pressures which may result in an inoperative condition to the starter drive housing, the engine flywheel starter ring gear, or the engine block at the outside edge of the starter boss.

Correction:
Inspect for a stored powertrain DTC code P0338. This DTC will NOT illuminate the "Service Engine Soon" light. If this code is stored, the Crankshaft Position Sensor, P/N 10456607, MUST be replaced and the remaining components inspected for damage (engine block at the starter boss, the starter drive housing, and the engine flywheel starter ring gear).

Notice : When DTC code P0338 is set, failure to replace the Crankshaft Position Sensor could result in repeated inoperative conditions of the starter or flywheel.

Important : Some flywheel wear is normal; broken or missing teeth and/or cracks, are not normal.


Follow Ups:





Good luck,

Matt