Cranks but will not start

Get a helper disconnect a sparkplug wire or 2 and ground it to the engine at least 3/16 away from ground -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs, coil's resistances, distributor pick-up coil, ignition control module, cam and crank sensors and computer Note: If it doesn't apply disregard it.

My first reaction when I see 0 volts is my probe isn't making good contact. To double-check, unplug something so you can touch the meter probe right to the terminal without having to back-probe the connector. If you don't see 12 volts there for that one second after a helper turns on the ignition switch, that would rule out the sensors.

If there is indeed no voltage ever on that wire, first check fuse 5, a 20 amp. Next, swap the automatic shutdown (ASD) relay with a different one like it. If there's still no voltage for that first second, bypass the ASD relay, then measure the voltage again. You can bypass the relay by using a jumper wire or stretched out paper clip between terminals 30 and 87 in the left diagram below. You can also pop the cover off the relay, reinstall it that way and squeeze the contact. Also watch that relay to see if the contact moves for one second after your helper turns on the ignition switch.

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Dandy. That means the signal is missing from the new crankshaft position sensor or the camshaft position sensor inside the distributor. Was there a thick paper spacer on the end of the new crank sensor, or did it have a thin plastic rib molded onto the end? Those are to set the critical air gap. If you didn't have a spacer on the end, the sensor could hit the flex plate and be broken.

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The cam sensor is a possibility. Have you checked for diagnostic fault codes? Do you know how to do that by cycling the ignition switch?

Measure the voltages on the distributor wires. The black / light blue must have very near 0 volts. The orange / white must have 8.0 volts. The black wire must have 0 volts. The dark green / orange wire must have battery voltage during cranking.

Next, switch the meter to the 20 volt AC scale to measure pulses. I've never checked these myself, but the tan / yellow should have somewhere around 4 volts. If that is present, the cam sensor is working. The black with gray should have something but it might be relatively low. An oscilloscope is really needed to view the waveforms accurately.

Either the signal is missing from one of those sensors or the computer is not recognizing them. What you will need to do is find someone with a scanner that can read live sensor data. View the two sensors to see if they are listed as "no" or "present". The display will switch when you start cranking the engine.

The Chrysler DRB3 will also let you fire the ignition coil to verify that part of the distributor is working.

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The green / orange wire is another feed to the alternator along with the distributor and the injectors. You will have voltage on all of those points at the same time. If you have voltage at the alternator during cranking, you have to have it at the distributor too. The only exception would be if the wire was broken between the splice and the distributor, but that can't be the case because then you wouldn't have voltage at the distributor for the first second. Since you do, we know that wire is good.

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It's starting to sound like the distributor is the problem but to verify that, you need to have someone connect a scanner to see if one of the signals is missing from the cam or crank sensors. If both signals are present, the timing belt may have jumped a few teeth. If the timing is wrong, the computer will not turn on the ASD relay to prevent the engine from starting and to protect the valves. There should be a code then for "cam and crank sync".

First check all the vacuum hoses for leaks. If you don't find any leaks, remove the fresh air tube from the throttle body, then use a flat piece of wood to block off most of the air intake. If you can completely block it and the engine continues to run, there is a major vacuum leak somewhere. If the engine slows down, gradually slide the piece of wood to the side to expose more and more of the intake opening. As you do that engine speed will go up, then the automatic idle speed motor should start to bring engine speed back down. The Engine Computer may have been running that motor to open up the air passage to get engine speed up to what it was expecting to see when you were cranking on it. Now that it's running, the computer will see that idle speed is too high but it could take a little time for it to run the AIS motor back down. Also, if you had the battery disconnected during the previous problem, the computer will have to relearn "minimum throttle" before it will know when it must be in control of idle speed. Until that is relearned the computer might not try to adjust idle speed to the correct speed. If necessary, you can remove the two torx bolts holding the AIS motor to the throttle body, pull it out and extend the pintle valve by hand. It will pull out very hard but it can be done. Reinstall it that way and try to start the engine. If it doesn't start right away, you might have to hold the gas pedal down 1/4".

To meet the conditions for the computer to relearn minimum throttle, drive at highway speed with the engine warmed up, then coast for at least seven seconds without touching the brake or gas pedals.

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