S40 Won't Start
 

2000 Volvo S40. I am unable to get my car to start. The motor turns over but will not crank. I checked the codes in the computer and it first said that my Camshaft sensor was bad so I replaced it. I tried to start with no sucess. I re-ran the codes and then it told me the camshaft sensor and the crank sensor were bad so I replaced the crank sensor as well. Still no success. I have checked the timing belt and the motor is in time. I have pulled and checked the injectors and they are firing fuel. I have pulled and checked the coils and plugs and they are firing. I am at a loss. The only thing I cannot figure out is when I am turning over the motor every so often the motor hesitates and the lights in the car dim and then everything goes back to normal. I hooked up my scanner to the car and tried turning over the motor again while the scanner was hooked up and when the motor hesitates and the lights dim the scanner looses power as well. Does anyone have any ideas.

Turning over and cranking is the same thing. Sounds like it's cranking but not firing (running), cranking but will not run, cranking but will not start.

For a car to run, it needs 5 things; air, fuel, spark, timing, and compression.

Since you said you checked the timing, are getting fuel, are getting spark, you're narrowing it down. You could do a compression test to see how much compression you're making in each cylinder. There could be some blow by in one or more of your pistons. I've had to do this on my Eagle Talon a number of times. Good luck!