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Fuel pump problems PLEASE HELP

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Old Sep 21, 2006 | 09:29 PM
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Default Fuel pump problems PLEASE HELP

I just finished a a4 to m6 swap and a motor swap at the same time. The only thing holding me up now is the fuel pump. The pump itself works outside of the car, but it isnt pumping fuel when in the car. The fuse up front is not blown and there is no problem with the relay up front. Does anybody know what my problem could be? The car ran before the swaps. Also the fuel guage shows empty even though the tank is 1/4 to 1/2 full.
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Old Sep 21, 2006 | 10:30 PM
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Works outside of the car as in you're letting it run without it being submerged in fuel?
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Old Sep 21, 2006 | 11:51 PM
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No I had it in the tank and hooked up a hot to it
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Old Sep 22, 2006 | 12:16 AM
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Sounds like a wire's been pinched when you did the conversion then.
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Old Sep 22, 2006 | 01:17 PM
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I dont believe a wire is pinched because when I bypass the fuel pump relay it will pump. I also just checked and fuel isnt the only problem. I am also getting no spark. Could this be a problem with the BCM? I did swap computers from a '00 a4 to a '00 m6 with a tune in it. BTW I have tried with both computers, no luck with either
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Old Sep 22, 2006 | 08:43 PM
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Soooo then it could be the relay?
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Old Sep 22, 2006 | 08:46 PM
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No we have switched with a known working relay.
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Old Sep 22, 2006 | 08:55 PM
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You gettin any codes from this?
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Old Sep 22, 2006 | 08:56 PM
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dunno it will be at my shop in about 5 minutes
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Old Sep 22, 2006 | 09:33 PM
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The computer is not getting comunication to our scanner. Any ideas ?
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Old Sep 22, 2006 | 09:59 PM
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Check the powers and grounds of the PCM. Make sure the grounds are connected properly to the back of the drivers side head. Sounds like the PCM is not activating the fuel pump relay. When you turn the key to the on position (dont try to start), have someone put their finger on the relay and see if it clicks as the key is turned on....after approx. 2 seconds it should click again and turn off power to the pump.

If its not clicking, the PCM isnt sending the signal, or it cant...IE broken wire, bad ground, etc.
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Old Sep 22, 2006 | 10:03 PM
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it is clicking. We also have the ground on right. I am getting a good ground to the obd2 and a good power. Still no fuel pump turning on and we are also not getting any spark.
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Old Sep 22, 2006 | 10:05 PM
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Do you have power at the pump when the relay is on for 2 seconds?
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Old Sep 22, 2006 | 10:17 PM
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not sure yet i am going to check that next and the power at the crank sensor. I am getting the computer pin out right now.
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Old Sep 22, 2006 | 10:45 PM
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ok i have the fuel pump working and good fuel pressure and still no spark. It just cranks and cranks
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Old Sep 22, 2006 | 10:55 PM
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How'd you get the fuel pump working?

Are you getting power to the coils?
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Old Sep 22, 2006 | 11:31 PM
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dunno the pump just started working. We are getting power to the coils but nothing out of them. We tested this through a modis and an ignition scope so we know there is definately no spark.
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Old Sep 22, 2006 | 11:41 PM
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Crank the engine while monitoring engine RPM on the scan tool. Are you getting any RPM?...if so your crank sensor should be ok. Security lamp on by chance?...check that too.

With a test lamp connected to ground, probe both sides of the following fuses with key on engine off: INJR1, INJR2, ENG CTRL, ENG SEN, A/C CRUISE. If all the fuses dont light on both sides of the fuse, you may have an ignition relay problem.

If all fuses are ok, use the scan tool to make sure the ECT sensor is reading correctly. If the engine is cold, compare to the IAT sensor for a similar temp.

You may also try to disconnect the MAF and then try to start. Let me know what you find on these steps and we can go from there.
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Old Sep 23, 2006 | 01:02 AM
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We have called it a night. Tomorrow we're going to change the ECT sensor and possibly the crank sensor (even though we were getting a reading). Any other ideas?
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Old Sep 23, 2006 | 08:19 PM
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Alright get this. This morning i came in and checked a few sensors and tested the computer for power. Pin 57 on the computer. Anyways as soon as we cranked to see if the light would flicker on the test light it fired right off. So we changed computers to put the computer with the tune in it and same thing happened. No spark and no fuel so we tested the wire at the computer and it fires right up.
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