Need help...No spark on 94 buick Roadmaster w optispark system. Battery charged, fuel pump 47 psi, replaced ign cntrl mod & MAP ( because tested 1.3k and 306k ohms when expecting 1.9k and 17k ),
Coil primary windings @ 1 ohm, sec @ 8.5K, opti pin feed from ECM at 5v,5v meter and 12v test light, &gnd (ABCD), Ign Cntrl Mod now at 12V DC at A&D pins w B pin at 2.8 V AC & C gnd.
Initial code 41 on dashboard diag and now cleared after replacement of Ign Cntrl Module. No code errors, but no spark ????
check the carbon and the spring in side the distributor cup 2nd change the high tention lead from the coil to distributor 3th ignition on remuve the 2 wires from the coil check the curen 12 volts as + conect to the coil and 4th check the black wire is your - with test light then conect to the coil good luck.
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First you want to know if your ignition system is working, so have you checked for spark?
If the answer is no, go to a parts store and buy a calibrated spark tester, real simple and inexpensive. Hook it up to one of your spark plug wires, crank the engine over with the key (as if you were starting it) and see if you get a strong blue spark. You will need a helper to turn the key while you watch for spark on the tester. If you have good spark, you can assume the ignition system is working good, so that's not the problem, nor is the cam sensor a problem. If you have spark and still no start, it likely is a fueling problem- see if fuel pump is turning on, check injector circuit-things to do with the fuel.
If you find no spark when cranking, something in the ignition system is the problem. Not necessarily the cam sensor- that sensor is for the computer to synchronize fuel injector timing with the intake valves opening. For the computer to determine spark timing and advance, it uses the crankshaft position sensor. So that sensor is more tied with the ignition system, and is often at fault when spark is lost. Other things, too, like the ignition control module, but those are things to check when troubleshooting the ignition. A repair manual should have a troubleshooting flow chart, or at least some steps or procedure when troubleshooting the ignition. Good luck.
I have a 94 Roadmaster and occasionally my pass key light comes on and car won't start....however if you turn off the key and wait 3 minutes you can try starting it again. Sometimes it will start
41-47 PSI (Pounds per Square Inch)Position the ignition switch and the A/C system in theoff position. Install a fuel pressure gauge to thevehicles fuel rail or fuel pressure test port.Confirm that no leaks are present, and visuallyverify the PSI reading on the gauge with the ignitionin the on position.
you need to determine if it' a fuel problem or spark/ign problem ! pull a spark plug and lay on motor to ground it and have someone roll over engine and yuo watch for spark !
This engine uses a special flat cap and a standard rotor, right ? The spark comes into the cap and thru the rotor, then to the spark plugs. Have you replaced the rotor ? The spark can jump thru the rotor and ground thru the dist. shaft. Depending on where you are testing for spark, the coil could also be weak and not pushing the spark to the plugs.
The injectors,coilpack and ign. coil are all bolt on's just pull and replace part (disconnect battery). I would not recommend taking on the fuel pump and waterpump unless you are a experienced auto technician.
DO A SPARK TEST USING A SPARK TESTER AND USE A FUEL PRESSURE TESTER GAUGE TO DO A FUEL PRESSURE TEST.FUEL PRESSURE SHOULD BE 41 TO 47 PSI.IF YOU GETTING NO SPARK.CHECK THE IGNITION MODULE FUSE.IF FUSE IS GOOD.SCAN IT TO CHECK FOR IGNITION MODULE FAULT CODE.PCM FAULT CODE CRANKSHAFT SENSOR + CAMSHAFT SENSOR CODE.IF YOUR FUEL PRESSURE IS 0 CHECK FUEL PUMP AND FUEL INJECTOR FUSES AND RELAY.IF OKAY FUEL PUMP FAULTY.BY USING A SCANNER IT WILL SAVE YOU TIME AND MONEY.NEW FUEL PUMP ABOUT $300.00 AND A NEW IGNITION MODULE ABOUT $200.00.
Need to get a scan tool and look at the data stream while it is running for alot more info.Also any trouble codes.Sounds like initially,the engine isn't getting any fuel.I would have a pressure gauge connected to the fuel rail on the engine,so i could monitor the fuel pressure while all this is going on.Items to look at on the data stream would be timing,what timing is the PCM commanding for the engine.Also,have you checked for continuos power feed to the coils during this no start condition,and fire at the plugs while cranking.You could possibly still have spark,but maybe it is extremely weak?I have seen bad ignition switches cause weird problems before too.Many things power up through the ignition switch,just a thought.Have also seen bad PCM's cause strange problems..38 volts is a little on the low side for GM.Usually see those at,at least .50 and up,and rise steadily while pressing the throttle,up to just under 5.0 volts.Potentiometer with 5 volt supply.Vacuum leak can be checked with engine running at a steady idle speed,spray brake cleaner all around the intake manifold and listen for engine speed change.
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