2003 concord, 2.7 engine v6 crank engine 1st time wont start. Turn key off and crank again and will start.. If warm engine and not sat long will fire first crank.

if crank wont turn starter may be locked in take starter off and try to turn over by hand

When it won't start I'm guessing you can not hear the starter turning the engine over. If so when it is acting up it should be pretty easy to see if there is power on the small wire at the starter with the key in the crank position. If there is power there and there is power on the larger wire at the starter, again with the key in the crank position, than the starter is the issue. These are also known to have corrosion issues at the connections on the battery. It wouldn't hurt to give those a peak or even clean up those connections.

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4.3L V6 CPI - center port fuel injection . you need 62 psi .When cold give it a shot of carb.cleaner or starting fluid ! does it start then ?

415-455 kPa (60-66 psi

check your carburater.

sounds like the crank sensor do you know if you have spark now if not could be an ignighter.

I CHANGE CAM AND CRANK SENSOR,FUEL PUMP,COMPUTER BRAIN BOX AND COIL PACK STILL GETTING NO FIRE UNLESS I JUMP A FIRE WIRE FROM BATTERY

Check and make sure that the engine is not seized up. Does the engine turn over?

The cam position and crank position sensors need to be checked. A diagnostic test will determine the exact problem

A very common problem on the 99 S10 is a leaky fuel pressure regulator in the intake plenum.What happens is when the truck sits for a few hours or more the regulator leaks all of the fuel in the fuel injection system into the intake air plenum. This does 2 things, 1 it has no fuel pressure when starting and 2 it floods the air intake with raw fuel. Sometimes if you turn the key on wait 3 seconds then turn key off then turn key back on and just turn key to crank starter for a split second and wait 3 seconds.do this 3 times to repressurize fuel system then crank to start(you will hear fuel pump buzz each time you do this.also you may have leaky fuel injectors. Try to crank engine with the gas pedel to the floor. This will tell the computer to stop spraying fuel trhough the injectors and it will start. Joe ASE Master Tech

I am assuming this a cold weather only issue ?? Turn your key to on before cranking it over for about 5 sec to let the glow plug heat up a moment. Not allowing the glow plug to warm will wear out your starter.