cant get 4.3 vortec to start?
changed fuel filter fuel pressure regulator and fuel pump. runs if i put gas threw carb but wont run by itself
Update:ok i pulled #1 and it was completely dry..i pulled #1 injecter and turned key and no fuel sprayed out ..had a friend come over and he said i had plenty of fuel pressure going to the motor,,
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You need to diagnose this properly before you start sticking parts on it. You probably have a problem that is preventing the injector from working, or you don't have power to the fuel pump.
You need to determine;
1) Is the pump running/Is fuel pressure present? Key on- should run pump from PCM command for 3 seconds (with a minimum of 61psi as vortec injector poppet valves will not open below this crack pressure) When engine cranks and oil pressure builds, the oil pressure switch closes the fuel pump relay contacts, keeping the fuel pump running. (check fuel pump relay function by listening for the click from the relay and listening for the pump operation)
2) If fuel pressure is present in correct pressure; Pull #1 spark plug and put it back into the spark plug boot while laying the plug base against a grounded engine part. Crank and check that spark is present. If the plug is "wet" either the fuel is not combustible, spark timing is wrong or the spark is blowing out or taking another route under cranking resistance (like through a faulty cap and or rotor)
3) Check for spark to compression timing. Pull #1 spark plug and put it back into the spark plug boot while laying the plug base against a grounded engine part. Place one finger loosely over the plug hole and crank engine to verify spark at the time of compression. If both do not occur at the same time it will never start.
4) If plug is dry, check for injector power and command from pcm. If the pcm does not see rpm input from the ckp sensor it will not command function. If no power is pressent at the injectors, the pcm does not know it/monitor it as the injectors are controlled from the ground side. (verify fuses and fuse links)
#1 causes of vortech no starts; fuel pump pressure under 61lbs, bad or junk aftermarket cap/rotor, faulty crank position sensor, bad coil that allows spark blow out when high demand is placed upon it (like cranking condition) Security system inhibiting
This is about as far as one can go without a schematic and a scan tool
hopefully you installed the fuel filter with the arrow pointing towards the engine. the arrow is on the fuel filter.