My car won't crank. i turn the key and it sounds like its trying to crank but it never fires. It fired once but while idling a few seconds later it died and hasn't cranked since

Do you mean the engine won't crank or that it cranks but won't fire up?
Car won start Ricks Free Auto Repair Advice

i would check and see if spark pluges are firing. you can take one out and plug into spark plug wire then let the bottom of the plug sit on engine and get someone to try to start while you look at the plug to see if there is any fire. if you have no fire or fuel it would be the crankshaft sencer. it could be the timing belt but the motor would sound different turning over then it used to.

in the dark have the bonnet open & have someone crank the vehicle. you listen & look for where the spark is arcing. when found repair.

My guess would be the key switch.

1) Do you have spark? Crank sensor? 2) Another quite common prob with them is the key reader. either the little metal bump on the key worn or the reader at the barel where the key makes contact but from memory if that no good it won't crank (can't remember)

Sounds like your key is no longer actuating the starter/not matched to the vehicle key code, if you can turn it on but no cranking action is done when trying to start.

I parked my 04 sienna and cut it off 2 hrs latter I tried to start it and would not crank starter was fried replaced with new one now it crank but will not start I tried starting fluid same thing cecked fire to plugs fire once and quit until you turn key agin fire once agin replaced cam and crank senser no start what am I missing anyone thank ,lost..

It sure could be. But, first...by "won't turn over" you do mean it cranks at normal speed but won't start?
A simple test of the fuel pump is to stand by tank and listen as someone turns key to on. When first turned to on, your pump will activate for 2 or 3 seconds, pressurizing the fuel system, and then shut off if the engine computer doesn't get a cranking signal. Do you hear it come on? If not, then something's not turning your pump on. If you can hear it buzz on briefly, then maybe it's your filter. Another test: Spray a little starting fluid into your intake manifold (remove the big hose going into intake manifold) while someone tries starting it.If it doesn't fire and try to stay running, then it's probably an ignition problem. But if it does fire off, then you know it's a fuel problem-likely your pump or filter. good luck.

you said you repl dist cap that means you don't have a crank sensor you have electronic ing module. remove your elec ing module have it tested most auto parts stores could test your module, or check your coil at the neg terminal. should have power. if not you lost your primary volt from your batt.your secondary power is coming from your electronic ing module from the module to the pos terminal on the coil, when the eng cranks,from the coil to the dist cap , from the dist cap center to the rotor then out to the plugs,this all happen pervided the timing belt or timing chain is ok. the cumbustion chainber needs 3 things , thats fuel, air, and spark.

Sounds to me like it is out of time. Crank shaft sensor no.Good Luck.