Car stalls then won't start. No spark? ECU?

Tiny
TCAMPTAC
  • MEMBER
  • 1999 MITSUBISHI ECLIPSE
  • 137,000 MILES
My car will stall and then not start again. It's like I'm turning the key of. Its keeps getting worse. If I disconnect the battery and reconnect it, the car will start and run for a few minutes. I replaced the fuel pump, the relays, the ignition coil, new plugs and wires, just to try and fix it. Any help would be greatly appreciated
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Friday, July 5th, 2013 AT 12:47 PM

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Tiny
CARADIODOC
  • EXPERT
The parts you listed are all over the place which suggests you haven't diagnosed anything. Throwing random parts at a problem is the least effective and most expensive way to diagnose it and it introduces new variables the Engine Computer has to contend with. It will be cheaper and faster to get a mechanic involved.

The first thing you have to do is determine if you're losing fuel pressure, spark, or both. Check for spark right after it stalls. If it's there but the engine won't restart, you can try a squirt of starting fluid to verify fuel is missing.

If spark is missing you can skip checking for fuel and go right to checking if the automatic shutdown (ASD) relay is turning on during cranking. Since you didn't list the engine size I don't know which ignition system you have or how many ignition coils it has. You'll have to figure out which wire is the 12 volt feed to one of the coils and monitor that with a test light. A digital voltmeter can work too but you have to watch it closely at first. You should see 12 volts on that feed wire for one second after a helper turns on the ignition switch, then it will go back to 0 volts. A lot of digital meters don't respond fast enough to catch that. That's why test lights work better for this test. What is important is whether that voltage comes back during engine cranking. If you had spark, it came back and there's no need to do this test. If the voltage doesn't come back during cranking the camshaft position sensor and the crankshaft position sensor are the main suspects. Normally there will be a diagnostic fault code set that will indicate which circuit needs further diagnosis.
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Friday, July 5th, 2013 AT 4:09 PM

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