I have 2001 pontiac grand am gt 3.4l that shuts off going down the road and sometimes wont start at all it cranks with spark but wont fire but it doesnt do it all the time

What's missing ? Spark or fuel pressure ? Do you know how to test for these ? Video's on youtube show how to diagnose a crank no start .

it sounds like it kicked the timing chain , the last time you shut it off

I have 94 s 10..4.3 v6. it does the same thing have replaced fuel pump and filter,ignition module,cap rotor plugs wires,coil,ground strap...driving down the road jus dies like the key got shut off....for a while when troubleshooting through the parts you could get it to restart.....now when it dies it cranks really hard when trying to restart..ive checked the timeing its fine....if i wait a few min it will usually start...sometimes it will show a check engine light sometimes not......never know when it will happen sometimes jus down the the road from the house sometimes 100miles down the road......sometimes three times in a mile sometimes not for weeks at a time..Wtf...Im ready to shoot it like a lame horse....its a shame too its a sharp lil truck thats a two owner and never spent a night outside in its life...i knew the original owner ...i bought it with 90,000 on it it only has 148,000 now and still looks like new...

i have a non starting prob with the same motor. i am going to start with an air sensor

Their is a computer chip behind the antifreeze bottle check the second wire harness play with that while someone turns the key it happend to mine the same thing and started right up

You could have damaged the crank posistion sensor or the wiring to it.

replace the crank position sensor and/or the cam postition sensor

HAVE CAR HOOK TO SCANNER COULD BE IGNITION MODULE.

have you ever replaced the fuel filter.

when you replace crank sensor the crank sensor is going have to be reprogram or relearn before car will crank.