Im having trouble starting this 2000 4.3 blazer. Its my daily and has done this a handful of times. Its just cranks. i got fuel and spark. i dont have a fuel gauge tester so i dont the exact psi but it shoots out the Schrader valve. Cant even get it to start by spraying ether down the intake. the codes the popped up were P0338 which was a crankshaft position sensor circuit high duty cycle. i just replaced the crankshaft position sensor and no luck.