01 hyaundai elentra cranks won't start now. Replaced fuel pump an fuel pump relay, car decides when the fuel pump wants to turn on. If you don't hear the pump turn on car won't start, just cranks over. When it does decide to start car runs great, then park it, next day car won't start again. Has anyone ever had an ignition problem with these. I'm at a loss an been chasing a gremlin of a power drain also, I can't figure this out. Please someone help me out here.

 

Sounds like there could be more than one problem.
If the electrical drain manages to reduce power available to the vehicle , that could help with causing a "no start".

If tests confirm sufficient power is always available,then we need to look at the ignition system and fuel system.

 

I'm going to crawl under the dash an check the ignition wires from the key to the power side of the fuse box to the fuel pump relay, any suggestions on the fuel. Im thinking of cracking the cold start injector on the intake, to verify that I'm getting fuel to the intake. Its just weird, that it picks an chooses when it wants to start an run.

 

There is no cold start injector.
Check your owner's manual and see if there are addl fuses in the engine compartment.

Does your vehicle have the "Immobilizer" feature. Have you had a chance to check that out?

 

hanky. Im not sure if it does or not. I dnt know anything about these cars. Only ever owned or work on toyotas. And youtube an Google just isn't helping anymore, an I dnt have a manual for this car either.

 

You can usually view a copy of your owners manual on line, try it.

 

Anyone know where at the immobilizer is located? I dnt have a manual, an im still trying to figure this no start out with this car.

 

The immobilizer is a anti-theft system that depends on certain confirmation coming from a coded key that tells the system the car operator has permission to start the vehicle.

The key sends a code to a module in the system that is programmed to each individual vehicle, that way only the correct key will allow the vehicle to start and run.
A capable scan tool usually is required to troubleshoot these systems.

 

ok, ya an I dnt believe this car has a chipped key, but I've been wrong before. The key is just a regular key.

 

So just 8nstalled a brand new crankshaft sensor thinking that was my issue an it was a no go. Pulled #1 spark plug an checked for spark, no spark. Did I fry the computer trying to jump the fuel pump, I still have no power to the fuel pump relay with the key on, so now it just keeps coming back to ignition switch. Anyone have any ideas?