truck wont start

 
Today I get home at lunch turn my truck off and go inside. I came back out after lunch and my truck will not start....... Its not the battery, alternator, or any fuse. My fuel pump is working. Only thing I see different is when I put the key in the run position the odometer normally scrolls across then show s whatever message. Its not doing it now but all the other service lights are coming on including the gear letters. When I attempt to start it acts like it wants to start then it stops then starts the ignition cycle over.....ahhhhhhh I cant figure out wtf is wrong with it.
 
thanks for any ideas

Computer might be on the fritz

thats what I was thinking but I wanted to ask around before I went on the hunt for a fix/new one

Yeah they can be costly, have you checked ground wires?

Mine was doing the same. Replaced the computer at 400 and another 95 to flash it. My fuel pump was a problem too. The fuel pump would run but not good enough to start the truck. Another 200 for the fuel pump

Sorry. I'm no help here. Too many variables.

just go through what you need to start the engine,  test the spark, and make sure you have fuel pressure (and fuel lol i knew a guy who said he truck wouldn't start and couldn't figure it out and all it was, was that he needed fuel the gas gauge broke showing a full tank lol) then start checking other stuff like grounds.  also what kind of truck is it?   i was a mechanic until i found me a good welding job lol.  couldn't pass up the money.

2005 chevy crew cab 5.3L V8 yeah it has fuel, fuel pump is pumping fine, no bad grounds im almost convinced its the ECM.....finding the right one is probably going to be the hard part. Anyone know where a place to get one other than the dealership?

my truck did that and after only 2 months chevy finaly found out thast it was the ignition swith, same thing was happening, fuel pump was on and everything. but they still changed my fuel pump and my cylinder head, and wiring harness.

u can buy computers at just about any parts store but napa has good ones and most of the time they are preprogrammed on chevy's.  they will ask for some of your vin to make sure you get the right one.  advance and autozone has them too but i've had bad luck from them.  but napa and even oreilly's   has good ecm's