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Q: Truck not starting - 2002 Chevrolet Trailblazer

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Well it cut off on me while driving to get gas cause it was on empty so we relaced the fuel pump cause it wouldn't start but it wouldn't start after the fuel pump replacement but you can hear the pump come on and like I said the fuel filter is good and the gas is flowing thru the lines but it still won't start but the battery is weak can that have something to do with it not starting and also the computer had have me a code for the cam sensor and that has been replaced but still it won't start so what can it be cause I really need my truck it's my only transportation and I don't have money for high fixes

My car has 211125 miles.
My car has an automatic transmission.

A: Hi there, thanks for writing in about your ...

Hi there, thanks for writing in about your 1992 Dodge Spirit. A slow cranking motor can definitely impede a motor from starting. First thing you need to do is connect a battery charger and get the cranking speed up. As for any other problems you might have, I wouldn't make any assumptions. I recommend you check for spark, fuel, and injector pulse. Depending on what is missing will decide which diagnostic path to follow.

Spark problems will be coils, PCM, or a power supply issue.

Fuel pressure should be checked with a fuel pressure gauge. Your fuel pressure specification should be 48-52 psi with the key on. If you have released the fuel pressure at sometime, you may need to cycle the key once or twice to build the appropriate amount of pressure. If the pump is running, and it is new, you should have good fuel pressure.

You will need a noid light to check or injector pulse. A noid light is plugged into the injector connector in place of a single injector. Crank the motor and the noid light should flashed rapidly. You stated you had a cam sensor code. A cam sensor and a cranks sensor can cause the PCM not to fire the injectors and your noid light, or injector, will not fire. I would be checking these two sensors with the motor cranking using a scanner to watch the sensor waveforms.

Beyond the items stated above, your 4.2L motor has some camshaft chain issues as a result of bad chain tensioners. This can cause some strange driving issues and can often set cam sensor codes.

If you need help scoping this problem out, a certified technician from YourMechanic can come to your car's location to diagnose the starting issue and let you know what needs repair.

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