Truck Repair: ignition problem, crankshaft position sensor, chevy k1500

Question
QUESTION: I have a 93 Chevy k1500, the problem is it starts great runs for about 10 minute starts to rev-up and then dies, and I lose all ignition and will not start again until everything is ice cold. I have changed the rotor cap wires and coil. any ideas? Thanks

ANSWER: Hi Steve,
It is possible that your ICM (ignition control module) is bad. You will have to buy a manual or talk to a GM tech and ask how to test it. Computers do not like heat so if this module is on it's way out it may not operate at all once it gets warm.

Good luck,

Matt

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

QUESTION: I changed out the ignition control module yesterday, and to no avail it still is doing the same thing. any other ideas?

ANSWER: Hey,
Did you test the module to see if it was within spec? also, when it dies test to see if there is power at the coil and at the module. I recently had a complaint where the engine would not start when warm..it turned out to be the crank position sensor..apperently this is a common problem with chevy engines, but TEST it first before changing it. You are going to have to find some info on this thing for testing procedures. it may be something simple that we are overlooking but if you have a step by step procedure then you eliminate any possibility for error...changing parts is the worst way to figure things out. Chilton makes a pretty good manual....maybe talk to a GM technician (not the service writer) and see what he/she thinks.

Here is the TSB on the crank position sensor:

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:




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

QUESTION: I have a Haynes manual, No I did not check to see if the ignition control module was in spec, the shop I bought the part from did not have the capability to do so. And like I said before the truck runs great starts easy when cold and dies all on its own, and after it heats up it spits and sputters before dieing. I do not see a reference to a crank position sensor in my book. Its a 1993. I will check for power at the coil, but I have no spark at the plugs after it dies. I will keep trying. Thanks.  

Answer
hey, I found on a corvette forum where a guy had a 93 vette doing the same thing, turned out to be the distributor, also another guy on there had a similar problem and it ended up being the temp sensor telling the ecm it was 0 deg F. The ecm needs to know what position the engine is in..on early 90s fords there was a sensor in the distributor. it's possible that chev did the same thing. try googling your complaint and see what comes up...gauranteed your not the first to have this issue so see what is out there. sorry I can't be more help...all my training and experience is heavy duty diesel trucks.

good luck