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I currently own a 2002 Oldsmobile Alero. I recently dropped money into it for maintenance, including brakes and a new battery. I have other issues with the car, but mostly I'm confused and my day gets disrupted with this one.

From what I understand, it is a crank, but no start. I understand this to be (since I'm a car newbie, as far as internal workings) that the starter turns over and attempts to start the engine, but the engine fails to start. This first happened near a month ago, on a Saturday. I had it towed to my mechanic. Monday rolls around, and he says it started right up for him. He still ran it up and down the interstate, ran his testing equipment and could not find any issue.

Since then, I have had a roommate of mine who knows more about cars than I suggest a passlock failure. I don't believe this to be the case. The security light doesn't remain on when it fails to start. Every now and then, when running, I get a service engine soon light that stays on, but according to the ODB2 Bluetooth adapter I have, it's catalyst efficiency being below threshold (I have had this issue since I bought it, this is not new and was told the catalytic converter needs replacing, but is not required). I reset the code and no new code pops up. During failure to start, no code in the ECU.

I've exhausted the options for passlock as much as I can without disabling the system all together, since I doubted that to be the problem. I can get information from the car via the Torque app and my Bluetooth ODB2 adapter, but I don't know what to look for. Foolishly grasping for information, I found out that in all likelihood my O2 sensor is working fine (Sensor 1 Bank 1 is a funky looking sine wave, Sensor 1 Bank 2 flatlines, suggesting my catalytic converter works for now, from what I researched), but I am guessing that o2 failures would not stop a car from starting.

When it warms up some, my roommate will look at the fuel filter to see if that's dirty, but I wanted to see if there is anything else I should be looking at? The car runs fine if it starts up. I notice today that if I push the engine, while in park, to about 4000 RPM's, it loses RPM's then goes back up, and repeats that until I let go of the gas.

What am I missing? What is my mechanic and roommate missing? I'm open to all ideas.

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I'm thinking the problem may be your fuel pump. I've seen pumps behave the way you describe with it working on-again/off-again until it finally fails permanently. Plus, your descriptions of sustained higher RPM running with it going up and down could likely be pressure fluctuations coming from the pump. Luckily this is an easy thing to check if you have a fuel pressure gauge. There should be a Schreader valve (similar to a valve stem on a tire, but thicker) on your fuel rails near the fuel injectors which you can test it at. I don't know for sure, but would believe it should be in the 40-45psi range during normal operation (pretty standard pressure for that year of GM vehicle).

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  • I was afraid of that answer, as it sounds like labor costs a lot for the fuel pump (the video on YouTube made it look complicated as well). I don't have a fuel pressure gauge, but I think it's time I get one... – Demortes Feb 16 '15 at 23:03
  • Just a quick update. The car wouldn't start one day, and I have yet to check the fuel pressure. Annoyed, I got under the car and tapped on my fuel tank a bit. It started right up and I have yet to have the issue again. – Demortes Mar 29 '15 at 8:13

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