My engine cranks but no start up?

AGARRISON19

MEMBER
1996 CHEVROLET BLAZER
4.3L
V6
4WD
AUTOMATIC

I have no background on this truck I purchased it out of someones yard and replaced a ball joint and catalytic converter after purchasing so it would be drivable. A few months after a purchased it, the blazer began this problem I used to wiggle the wires and clean the battery and it would start. Shortly afterwards it began not starting and after I would stop trying to turn it over it would jump as if it was trying to start. I ran a few test and got a P0336 code and replaced the crank sensor. Then I began to test for proper grounding, a found out there may be a short in a wire for the ICM. So far I've just been throwing parts at it (ignition coil, crank sensor, PCM, and ICM) ; this is my dream truck and I intend on keeping it is there anything that I can do to get it up and running?

5 Replies

JACOBANDNICKOLAS

MECHANIC
108,133 POSTS

This sounds like a fuel pump has gone out. When you turn the key to the on position without cranking the engine over can you hear the fuel pump run in the tank for 5 seconds?

https://www.2carpros.com/articles/car-cranks-but-wont-start

Please run down this guide and report back.

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Wednesday, September 2nd, 2015 AT 7:22 PM

AGARRISON19

MEMBER
3 POSTS

I was thinking it might be the wiring but I wanted to make sure before I take another major unnecessary leap in the repairs. Im getting a P0336 code and have done numerous repairs. Im a college student and money is very tight so ive been DIYing with my dad (20+ years as a mechanic) in our free time. The only thing I havent checked yet is the fuel pump because I hear it come on and I have good fuel pressure.

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Wednesday, September 2nd, 2015 AT 7:34 PM

JACOBANDNICKOLAS

MECHANIC
108,133 POSTS

You do realize that is a cam sensor code, correct? Have you checked the cam sensor, the wiring to it. You mentioned several thing you replaced but not the cam sensor. The cam sensor is responsible for ignition spark and fuel injection timing. This code indicates that during the first few seconds of cranking the engine (to start it), the cam sensor is out of range. The signal it sends the ECM is incorrect and thus the engine won't start. Believe it or not, there are many things that can cause this problem for example, a bad sensor, wiring issues, the starter motor, the starting system, and even a weak battery. If you haven't already focused on the cam sensor, that is where I would start. If you have a real time scanner, see what signal is coming from the cam sensor when cranking so we can determine if it is working or not.

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Wednesday, September 2nd, 2015 AT 7:45 PM

AGARRISON19