My 4.3 chevy caprice wont start, i have tried or fixed :distributer, coil, module,fuses, battery,fuel pump,oil pressure swicth, and it still wont start, could it be my computer,bcuz the scanner wont pick it any codes, the check engine light stays on, except when the scanner is plugged in then the light goes off, but the car still wont crank

Have you done basic troubleshooting? Spark at plugs? Fuel pressure? Compression?

check your fuel pressure and oil pressure as well as oil pressure sender

Think the oil pressure switch keeps the fuel pump running once started. Suggest replacing Oil pressure switch. And no it won't effect oil pressure reading when it goes bad. The switch is a safety device. When you roll it over and the oil pressure drops the switch cuts off the fuel pump. Neat huh? Need some good feedback Thanks!

check fuel pressure most likely bad fuel pump. also check your oil sending unit or gauge. chevys run the fuel relay to the oil pressure switch in case the oil is so low the car wont start. sometimes the relay in between this circuit goes bad as well. if all is well check or replace the ignition module (located directly under coils) or distributor integrated if it has a distributor

You say no spark to the coil. does that mean that you have checked the power to the coil & getting none or are you getting no spark from the coil to the distributer cap? If you have no spark that is most likely the problem of not starting but you can always just check your fuel pressure to see.

my 1999 chevy suburban will start with starter fluid bbut wont stay running already replaced coil,rotor on distribitor,and oil pump cant seem to figure it out any ideas

CHECK BATTERY VOLTAGE FIRST IT SHOULD BE 12.5 VOLTS.IF NOT REPLACE BATTERY HAVE ALTERNATOR CHECKED.IF BATTERY GOOD.HAVE VECHICLE SCAN FOR PCM PROBLEMS - CRANKSHAFT SENSOR PROBLEMS OR CAMSHAFT SENSOR PROBLEMS.IF ALL IS GOOD GET A SPARK TESTER AND FUEL PUMP PRESSURE GAUGE TESTER.IF GETTING NO SPARK PROBLEM COULD BE LOOSE BAT.POWER SUPPLY WIRES AT IGNITION COIL MODULE OR IGNITION MODULE FAULTY.IF FUEL PUMP NOT RUNNING CHECK FUSE ABD RELAY IF BOTH IS GOOD FUEL PUMP FAULTY.

Check out your oil sending unit, fuel pump and relay, check for power (might be a fuse), the ignition control module (which if you remove it, can be tested for free at AUTO-ZONE), any related wiring, pick-up coil (inside the distributor), and possibly the ignition switch. If I can be any more help just as away.

there are large fuses in the relay box it could be one of these located in the engine compartment

Hello thank you for using FixYa.com for your answer my name is David.
You say it wont start in the normal way by just turning it on but if you pour gas in the throttle body
it will start sounds like you have a weak fuel pump most likely but there are a few other things that could cause it also .

1 Inspect Battery Damaged or faulty battery and/or connections. 2 Inspect Coil - Ignition Damaged or faulty ignition coil or ignition coil circuit. 3 Inspect Fuel Filter Clogged or dirty fuel filter 4 Inspect Fuel Injector Pressure Regulator Faulty fuel injector pressure regulator or circuit. 5 Inspect Fuel Pump Improperly functioning fuel pump or circuits. 6 Inspect Wireset Damaged, worn, or deteriorating spark plug or coil wire(s). 7 Inspect Control Module-Ignition Faulty ignition control module or circuit. 8 Inspect Solenoid Switch Damaged or faulty solenoid switch or solenoid switch circuit. 9 Inspect Starter Damaged, worn, defective, or faulty starter or starter related circuit. 10 Inspect Neutral Safety Switch Damaged or faulty neutral safety swittch or circuit. 11 Inspect Air Charge Sensor Damaged or faulty air charge sensor or air charge sensor circuit. 12 Inspect Fuse Corroded, burned, or shorted fuse may be interupting power source.