Chev Cavalier 91-V6 FI, Engine stopped suddenly and wouldn't start, please help.

Does the engine sound different than before when it turns over?

No, it sounds normal.

What if you tried using starter fluid or gas in the throttle body.

I didn't try that yet.

I kindof feel that it has got something to do with those injectors, the fuel rail assembly is full of fuel, but not reaching the cylinders. It is likely that the injectors were not activated to pass the fuel from the rail to the intake manifold. Having said that, I have not been able to locate the wiring diagram of the injectors, according to the manual, the injectors are controlled by the ECM, but I'm not sure where the wires and relays (if there is one) are.

Another thing I would like to know is how to chech if the injection signal (from ECM?) has been passed on to the various injectors while the engine is turned over, there is nothing can be found on the manual I have.

Thanks very much for you response.

I have just check the code, only code "34" is set. On the manual for this model, there are two possibilities, either Mass Air Flow sensor or circuit, or Manifold Absolute Pressure sensor circuit. I guess I got to check these two sensors tomorrow?

I have checked the Manifold Absolute Pressure sensor according to the procedure in the manual and it appears that the sensor is at fault.

The procedure is ".... Unplug the electrical connector from the sensor and, using jumper wires, connect terminals A and C (the two outside terminals) to their corresponding terminals in the electrical connector. Connect the positive lead of the voltmeter to terminal B (the center terminal) of the sensor and the negative lead to ground. With the ignition on (engine not running) the voltage reading should be about 4.5 to 5 volts. Start the engine and let it warm up. The reading should now be different from the original reading, and should fluctuate with changes in engine rpm. If it doesn't, check the vacuum hose for breaks or blockage. If the hose is OK, the sensor is probably bad........."

My reading was "0" volts from the center terminal in the electrical connector while the ignition On, I couldn't see if it fluctuate since my engine couldn't be started.

One thing, how could the sensor has 4.5 to 5 volts when the electrical connector is not connected? Does the manual mean the center terminal in the electrical connector? I have also checked the center terminal in the electrical connector and the reading is also "0" volts.

I agree that the engine should run with a bad Manifold Absolute Pressure sensor, however, it may depends on how bad is the sensor. It seems that my Manifold Absolute Pressure sensor is dead, so it should not be ruled out that the Manifold Absolute Pressure sensor is the root cause of not starting.

That's what the "using jumpers" part is for. (IOWs, it's not disconnected)

Yes, I redid the test and the voltage is 4.75V, within the specification.

It seems that the next possible suspect is the computer module, Mike, if you are still following this thread, may I ask what happened to the

1992 3.1 engine, did you have to change the computer module, or something to that effect.

Thanks again for all the response above.

I haven't had any similar problems with my Beretta, but most engines since about

1990 use a manifold absolute pressure sensor, throttle positi>

Thank Mike,

It finally comes down to the simplest: the timing chain broke! I opened the front volve cover and turned the engine over, nothing moves, all the six volves are not moving at all. So it seems that when I'm turning the engine over, the only thing rotate is the crankshaft, the camshaft don't move at all.

I'm going to remove the timing assembly, and probably replace all the related parts.

Thanks again Mike, for all the helps.

Interesting. Earlier you said it did not sound different turning over. When my 2.2 cam chain went, it could tell right away something was different. The sound was different and it spun faster.

Bob

When the timing belt on my old dirty dodge broke the engine made kind of a different hollow sound when I tried to start it. Like a different kind of a whine.

It did sound no different to me, as well as to an old mechanic who has over 40 years of backyard mechanic experiences. I guess this may be dependent on the position of the volves when the chain went?

Another possibility is that, due to the fact electronic components break down very often now days, people tends to develop a tunnel vision that first thing to look is the electronic component when something went wrong.

Thanks again Mike,

I should do that.