I have a 2004 dodge ram 1500 with a 5.7hemi engine. my vehicle cranks but wont start up. I replaced the crankshaft sensor and still nothing. I banged on the fuel thank which help start the vehicle. bu

I am assuming this engine ran before the repair? Not sure why you would replace these unless there was a problem. Check and make sure all wiring connectors disturbed during repairs were hooked back up, in particular connectors to the crank sensor, cam sensor, ignition system, etc. Make sure wire and/or wiring harnesses were not damaged, pinched, stretched or otherwise compromised during the repair. Make sure fuel/ignition/engine computer fuses are not blown. Try starting vehicle with a shot of starting fluid in the air cleaner. If it runs briefly but dies look for a fuel related issue such as no fuel pressure, or if the vehicle has an anti-theft system a problem with that as in some systems it disables fuel injector pulse. If the engine does not respond whatsoever to a shot of starting fluid check for ignition (spark). If not found double check crankshaft and camshaft sensor wiring. It is completely possible the sensor or sensor(s) you replaced are bad as well. Nothing guarantees a sensor to be "good" even if it's a new part.

it will be less expencive for you to use the right part, different computer not a good idea good luck

Best possibility is that you failed to replace or reconnect the crankshaft position sensor after changing the transmission. It is positioned at the rear of the engine at
the top of the transmission bell housing assembly. If this is missing, disconnected, or damaged, the vehicle will crank but never start.

run fault codes and check for ambient air temp/water temp/cam/crank position servos/sensors faults. Something that is controlled by temperature that is connected to the cpu is telling it not to start as it is out of parameters.

Always start with the basics. Remove the battery terminal ends and inspect for corrosion. This may appear as a black looking surface where the terminal end and battery post make contact. The B+ post/end is the most likely side for corrosion. If the engine is "cranking" fine then you are either not getting "spark" or fuel. The crankshaft position sensor is the most common "crank but no start" solution. There could be a code stored in the memory of the on-board computer.

well if ur not getting spark and u changed all of the ignition components lets think about the computer in order for the ignition to work you have crankshaft position sensor that fires the fuel injectors and the spark change that and if still nothing then change the camshaft postion sensor that sensor tells the computer that the 1 piston has came all the way up and it tells the crankshaft sensor to do its thing

Check that the engine immobiliser is working correctly because if it isn't it won't allow it to fire.

the crank sensor is on the back side of the engine just above the oil pan there will be two sensors there one is the crank sensor and the other is oil presser sensor. All so check the wires from the crank sensor to the cam sensor. If you think it is the timing belt pull the cover and check it. hope this helps.

On the 4.7L, the cam position sensor is located on the right cylinder head (thats the passenger side) toward the front below the valve cover gasket. Not on the front of the head but on the side where the exhaust manifold is attched at the forward end of the head. The crankshaft position sensor is located on the same side (right) but is at the opposite end of the engine between the bell housing and the block. The crankshaft position sensor can be replaced without removing the engine or transmission, it just looks tight. Also, on the crankshaft position sensor, it slides out of a rubber gromet. Here's a few pics to help.

I posted in your premium again to help you out. I feel it is a crankshaft sensor. Try and clean the crankshaft sensor and or replace. Also if its at a mechanic, He can check if the computer is working by seeing if a signal is coming to the injectors when trying to crank. Ive done it before its not that ******* a gas vehicle diesel shouldnt be much different. other then its a diesel of course.