04 STI no start - fuel pump not turning on - HELP!!! - Subaru WRX Forum
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post #1 of 5 Old 08-28-2010, 01:18 AM Thread Starter
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04 STI no start - fuel pump not turning on - HELP!!!

Here is what I know:

1) No prior starting issues or fuel flow issues of any kind, car was running like a champ.
2) Starter was turning, starter was engaging, battery was fully charged, car would not start.
3) Listened for 2 second fuel pump operation when switching ignition switch to on position... no noise, so fuel pump was definitely not turning on.
4) After I got the car home (tow truck) I tested the voltage of the power supply wires where they connect above the fuel tank on the fuel tank access cap. With key turned to on I had 10 volts. I then hooked the battery straight up to the male ends of the same connectors (right on top of the fuel tank) and the fuel pump turned on, so I know the fuel pump works.
5) I went to checker to rent an OBDII reader. Plugged it in, device turned on, after I turned the key and tried to sync up the reader, it said "unable to establish a link with the vehicle". I know the OBDII reader works because I then tested it on my wife's Scion xB and it worked like a charm... What am I missing here?

I figure that if the fuel pump works, if I was getting juice through the wires all the way to the fuel pump, and my battery was charged at the time of the no start... there must be another reason why it is not turning on, like the computer is throwing an error code. That's why I got the reader. So I will pose two questions in an effort to save me from the clutches of the dealership. Please help with:

1) Why would the OBDII reader not be working? (Innova 3120 - Can OBD2)
2) Is there anything you guys can think of that would prevent my fuel pump from turning on? I know there are probably a million things, but give me all your guesses and troubleshooting ideas. I am far from good at troubleshooting, but I hate taking my car in .
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post #2 of 5 Old 08-28-2010, 11:56 AM
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This is going to sound silly, but have you replaced the fuse? It doesn't have to be blown for it to have an issue, but it would have to be close to not supply full power. Also, there's a relay somewhere in the line, so if you can find that, make sure it's actually clicking back and forth when you flip the ignition.

Regarding the reader, have you tried plugging it in after the car is in the on position? Some cars won't work right with code readers unless they are plugged in at the right time. I know my code reader doesn't work unless the car is actually on, so maybe that has something to do with it, as your car won't actually start. It could be as bad as the ECU having a problem, and at that point maybe a reflash would work, or maybe you'd need something else? That part I don't know. But I would start there.
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post #3 of 5 Old 08-29-2010, 04:42 PM
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If you had 10 volts at your connector I would say you have a bad connection somewhere. That voltage should be at least 12 volts.

If you are good with electrical systems I would continue to trace the electrical path back to the battery. You should find a point where the voltage is 10 volts on one side and 12 volts on the other.

For a quick shotgun method I would replace the fuel pump relay since that is a switching device it could have high resistance in it. Also check all connectors from fuel pump back to the battery for corrosion.

Good luck and let us know what fixed it. I hate open ended posts!
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post #4 of 5 Old 08-30-2010, 03:13 PM Thread Starter
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Thanks for the suggestions guys! I really appreciate it! I gave up and had my car towed into the stealership . They have already spent 4 hours on in and are scratching their heads. Apparently they are waiting for a call back from subaru headquarters, I guess they need some technical advice Well, I will let you guys know what it ends up being for sure.

Is there any type of fuel pump cut-off with the built in STI alarm system? Not that my alarm was triggered, but i'm just wondering....
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post #5 of 5 Old 09-01-2010, 06:39 PM Thread Starter
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Update: Dealership called, they are replacing the ECM (covered by subaru even though my car is not under warranty). They have never seen anything like this before. Long story short, I should have my car back in 2 days if all goes well at the cost of a few hours of dealership diagnosis.

That really makes a statement about how Subaru treats their customers... They had the attitude of "Hey we've never seen that before and even though your car isn't under warranty we want to replace it for you because it shouldn't have gone bad at 60k miles... or ever for that matter." I especially appreciate this because my car is still stock. It's not like I was messing with it and caused it to malfunction.
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