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Problem:

While driving on the freeway, the car shut off suddenly. No lights or starter functioned. Also, at intermittent times, the engine would rev up without pressing the gas pedal. you could be at a stop light and the engine would randomly rev up to 5k then go down.

Prognosis:

The first problem led me to believe that the alternator/charging system has failed. The second problem led me to believe that the Throttle position sensor (TPS) may have worn out, The Mass airflow (MAF) may be dirty, or somewhere in the fuel system could be a problem. This system consists of A: Return-less fuel rail, fuel rail pressure sensor(FRPS), fuel injectors(4), evap, a fuel pump, and a computer located under the passenger seat. also an inertia switch for safety.

Action:

So I decided to replace the alternator and battery first. My reasoning is because regardless of any bad sensor or fuel system part, the car would still have some electrical power or turnover in which case my friend said she had neither.

After replacement of these items we attempted to start the car to no avail. The engine had a very solid and even cranking, but it just did not seem like it was getting fuel. At this point I checked for spark(which it had), then checked for air(which it had). As for fuel, I crawled under the rear of the car and disconnected the fuel line that hooked up to the outlet of the fuel filter. I had my friend crank the engine over as I watched for fuel to come out of the filter, but there was none, just some residual when I initially unhooked the line. I checked the fuse box on the firewall, and all fuses were fine. could it be a relay? I wasn't really sure how to test this. We called it a day and decided to work on it another time.

Action items:
1. check all wires and harnesses for defects or damage
2. clean and check associated sensors (MAF, TPS, FRPS)
3. Verify fuel pump is working and injectors are pulsing
4. Use sea foam in tank

Im leaning towards the fuel pump and possibly the FRPS. I tried to take out the FRPS and I may have damaged it doing so, cause it wouldnt budge, but i left it alone after a few pulls. I just need someone to point me in the right direction, and make sure my tests were effective. thank you! =)
 
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