Trouble starting

[Marcelo]

can anyone help me out with my 4.3 vortec. It cranks good but will stop mid crank. Starter is good, but i do have these codes that i think have to do with it.

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[Schurkey]

Stops mid-crank? HOW do you know the starter is "good"?

Defective or undercharged battery--insufficient amperage capacity
Defective or corroded battery terminals. "Black" corrosion is an insulator. Terminals need to be shiny.
Defective battery cables
Failing starter motor
Internal engine problems--hydrolock, broken parts, etc.

I would start by testing voltage at the battery cable connections on the battery, before cranking (should be 12.6--12.7 volts) and while someone is turning the key so that the engine is cranking (should be AT LEAST 9.6 volts, more is better, and 10.6+ is typical for warm weather.)

Nothing shown on the scan tool should interfere with cranking except--MAYBE--the cam/crank sensor correlation, and then only if the synch is so far off that the spark is jumping to the wrong terminal of the distributor cap.

OTOH, Vortec caps have a bad reputation for failed insulation, so that the spark jumps from one terminal to another. So I could imagine a failed distributor cap causing momentary problems when cranking. Seems kinda unlikely, though.

 

[Marcelo]

Stops mid-crank? HOW do you know the starter is "good"?

Defective or undercharged battery--insufficient amperage capacity
Defective or corroded battery terminals. "Black" corrosion is an insulator. Terminals need to be shiny.
Defective battery cables
Failing starter motor
Internal engine problems--hydrolock, broken parts, etc.

I would start by testing voltage at the battery cable connections on the battery, before cranking (should be 12.6--12.7 volts) and while someone is turning the key so that the engine is cranking (should be AT LEAST 9.6 volts, more is better, and 10.6+ is typical for warm weather.)

Nothing shown on the scan tool should interfere with cranking except--MAYBE--the cam/crank sensor correlation, and then only if the synch is so far off that the spark is jumping to the wrong terminal of the distributor cap.

OTOH, Vortec caps have a bad reputation for failed insulation, so that the spark jumps from one terminal to another. So I could imagine a failed distributor cap causing momentary problems when cranking. Seems kinda unlikely, though.

Starter is new and also the distributor. It cranks fast. Gonna try fixing the cam/crank code then look at what your telling me. But thanks

 

[Marcelo]

Starter is new and also the distributor. It cranks fast. Gonna try fixing the cam/crank code then look at what your telling me. But thanks

And i remember it start doing that after i replaced the crank sensor.

 

[HotWheelsBurban]

And i remember it start doing that after i replaced the crank sensor.

Maybe there's a problem with the wires on the crank sensor harness? I've not had this with my trucks yet but have read it's a common thing.

 

[evilunclegrimace]

I'm with Schurkey on this one. You either have a problem with the cranking system or the distributor is out of time. I have not seen a CMP sensor cause a failure to crank the same goes for a Crank position sensor. Any time I have seen a crank or cam sposition sensor fail it resulted in a no start but not a no crank.

 

[HotWheelsBurban]

Have you replaced the "crank" fuse? I think it's a 10amp, red fuse in the dashboard block. Look in the owners manual or on the fuse block lid for exact location.

 

[Erik the Awful]

The crank sensor doesn't control the starter circuit. You have a bad connection somewhere in your starter wiring. Fix that first.