[Charles F. Smith]

Hair pulling time. In desperation, I'm hoping someone else has had to deal with this and can shed some light on the problem.
A friend's '97 Chrysler van with the 3.8 engine just quits running. After sitting for a while it will start up again and run for an unpredictable amount of time (20 minutes to 2 days) and just stop running again. When checked out with a Proto code reader it will signal "no cam signal" and "no crank signal" when it's cranked.
The van did this a lot less often when he kept the fuel tank level over 3/4 full and in the beginning it would run for weeks as long as he maintained the fuel level up near full but now this doesn't seem to help.
Anyone have any insight into this problem?
Charlie Smith

[cantspel]

It is normal to show no cam or crank signal when cranking. Since fuel level seems to have some affect on it, have you checked fuel pressure? You could have a pump crapping out. Fuel pumps are cooled by the fuel in the tank. More fuel may have allowed it to stay cooler and run longer. Do you actually have a stored code for loss of cam or crank, or did you just notice that you were loosing it while cranking?

[Lonestar]

Ignition module? Those things would drive a person crazy, car would start up and run fine then just shut off when warm. Tow it to the garage where it would start up and run fine since it had time to cool. Mechanic would find nothing wrong and send it home where it would crap out again. Repeat cycle.

[67 Deuce 4 Me]

you should see a cam and crank sig an the scanner. I know for a fact ours does. when cranking it will say crank and cam sig yes or no. When cranking should say yes. The cam and crank sensor has the same power and ground wires but differant signal wires. I would suspect a chaffed or broken power or gnd cuircuit. Or most likely you have a bad PCM the ignition module is integrated into the PCM. Ive seen both problems at our shop several times.

[Weimer]

Let me throw this out there to give you a place to start.
It could be one of a few things...
1) ASD (automatic shutdown) relay. If there is no ignition(distributor) signal or camshaft or crankshaft reference sensor signal when the key is in the RUN position, the ASD Relay shuts down the power to the fuel pump,fuel injectors, ingnition coil and oxygen sensor. The ASD Relay is located in the Power Distrubution Center next to the battery.

2) The Crankshaft Position Sensor is located on the transmission bellhousing. It sends info to the PCM in regards to the crankshaft position. This sensor reads the slots on the torque convertor driveplate.

3) Camshaft Position Sensor sends info to the PCM to synchronize the fuel system with the ignition system. The signal is generated from a pulse ring located on the Cam sprocket. The signal is generated as the teeth on the sprocket pass by the sensor. The teeth on the sprocket line up with the sensor the voltage pulses low(approx 0.3 volts) and when the the notch between the teeth line up with the sensor the voltage pulses high(approx 5.0 volts). These voltage pulses are in turn sent to the PCM which in turn determines ignition timing.

As far as the fuel level being over the 3/4 mark, allowing the van to run is probably irrelevant to the problem. I am going to take a stab at saying that the weight of the 3/4 full+ tank is causing the van to sit at a slight (loaded) angle as compared to the angle of the van at 1/2 tank and below. Probably enough to affect the internals of the sensor(s) or loose wire.
Like I always say K.I.S.S. and start with cheapest solution first.

If that doesn't help, let me know and I will see what else I can come up with.
Later,
WEIMER

[Fatchuk]

Hi sometimes these are tough to solve...I would try this because you are accessing current information, no cam or crank signal ...does it only stall and no start when warm?...or when its cold ...if warm take a hose and pour water on the crank sensor if it starts, I would replace the sensor...it is probably the the most common failure for this symtom.. if it's fuel related you will have to do a fuel presure test hot and cold, and how quick the pressure drops when you shut the key off it should hold for at least a half hr... the fuel pump could be getting weak... as it gets warm, you said the problem seemed to be better when the fuel storage tank was maintained over 3/4s full the fuel pump is mounted in the tank and infact is designed to to be submerged in fuel so the fuel could act to keep the pump cool to lengthen it usable life, it is possible and probable that many people drive around on 1/4 tanks shortening the length of life the pump will work effeciently and I know it is another common failure on this symtom ..I'd probably go for the sensor...but you can't overlook the fuel pump with out more testing and information....fatchuk