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2004 Audi A4 fuel pump not working. Replaced fuel pump after…

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2004 Audi A4 fuel pump...
2004 Audi A4 fuel pump not working. Replaced fuel pump after finding that voltage was getting to the fuel pump while cranking however it did not fix the problem. Later voltage test showed 8 to 9 volts rather than 12 volts at the connector which I am assuming is why the pump won't work. I originally only had used a test light to confirm voltage other than a voltmeter. Fuse number 28 and number 34 have no voltage.
Submitted: 1 month ago.Category: Audi
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Answered in 12 minutes by:
1/6/2018
Audi Mechanic: Jaybird61, ASE Certified Master Technician replied 1 month ago
Jaybird61
Jaybird61, ASE Certified Master Technician
Category: Audi
Satisfied Customers: 2,304
Experience: Automotive Instructor at Palm Beach State College
Verified

Hi, My name is Jay

You need to check fuse 28 and 34 for power when cycling key on and off. Check to see what battery power voltage is? If battery voltage is above 12 volts when cranking the engine and pump and fuses are low voltage let me know?

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Customer reply replied 1 month ago
Hello Jay and thank you for your response. I will be able to check the voltage and about 2 hours and I will get back to you. When I mentioned that fuse number 28 and fuse number 34 did not have power that was when the key was turned to the on position. As you suggested I will try it in the cranking position when I get home. I have found in Google searches where people have had no power at fuse number 28 and 29 and 34 but that was on older Audis. FYI
Audi Mechanic: Jaybird61, ASE Certified Master Technician replied 1 month ago

They will only have power when the fuel pump relay is energized during cranking or for a second when key is turned on. Here is picture of where the fuel pump relay is left side under dash on relay panel. If voltage is low at fuses and pump but okay at battery then try replace fuel pump relay.

https://www.dropbox.com/s/b2ngc0miknwph07/2004%20audi%20relays.pdf?dl=0

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Customer reply replied 1 month ago
Hello Jay I checked at the fuse 28 and 34 while cranking and the voltage was 8 to 9 volts which matched what the battery has while cranking. And yes it does crank very slowly. I put a known good battery in the car and it did the same thing. I pulled the fuel pump relay number 167 out and tested it and it clicks fine and allows full continuity through the large lugs.
I put a battery charger on full Boost and it cannot maintain above 9 volts while cranking it's very quickly drops below 9 volts. I could not open the picture that seems to be in Dropbox for some reason.
Customer reply replied 1 month ago
But based on my previous investigation I believe I was correct with the fuel pump relay being number 167 all the way on the left underneath the steering wheel
Customer reply replied 1 month ago
I have not been able to find a free copy of a wiring diagram on the internet. I was hoping you would have access to that.
Audi Mechanic: Jaybird61, ASE Certified Master Technician replied 1 month ago

Give me a minute and I will send it for you but if you cannot open drop box I will need to send it as an email attachment for you. The fuel pump relay is the one on left in relay row. If your voltage is dropping below 9 volts then this affects the pump and computer. Have you scanned the computer to see if you have codes for a crank or cam shenos issue?

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Customer reply replied 1 month ago
I have not connected my scanner to it but I will I guess I assumed my scanner would not work on an Audi but I'm guessing I'm wrong give me a few minutes
Customer reply replied 1 month ago
I disconnected the big positive lug that comes off of the positive battery cable you know there's two cables going into there so I disconnected one and it made the voltage stay up to 12 volts
Audi Mechanic: Jaybird61, ASE Certified Master Technician replied 1 month ago

I will have to opt out for another expert that may have more experience with this problem. Please do not rate or respond or it will lock question back to me. Thanks.

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Audi Mechanic: Marty, ASE Certified Technician replied 1 month ago
Marty
Marty, ASE Certified Technician
Category: Audi
Satisfied Customers: 54,753
Experience: ASE & Bosch Master Tech. 30 years experience.
Verified

Hi, my name is***** need to replace the battery or connect jumper cables from another known good battery, preferably from a running car. Your battery voltage is too low. It sounds like the battery in your car is bad.

Let me know what happens.

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Customer reply replied 1 month ago
The battery is fine... I put another battery in it and it did the same thing until I disconnected the positive lug that's the battery post... use jumper cables and connected power to the lug that was removed and the car then would crank fine and would not go below 10 volts while cranking... the fuel pump had full voltage at that point and you can hear it running and the car started. So whatever is drying too many amps and lowering the voltage to the ECM fuse and the fuel pump fuse is offset second slug coming from the battery post
Customer reply replied 1 month ago
I need a wiring diagram
Customer reply replied 1 month ago
I will hook my scanner to it in the morning
Customer reply replied 1 month ago
For some reason a $5 charge and then later a $43 charge has hit my account. I did not think that would happen until we found out the problem
Audi Mechanic: Marty, ASE Certified Technician replied 1 month ago

Can you post the vin number?

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Customer reply replied 1 month ago
Sorry I will have to do that in the morning also
Customer reply replied 1 month ago
I will get the VIN number for you in the morning
Audi Mechanic: Marty, ASE Certified Technician replied 1 month ago

OK

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Customer reply replied 1 month ago
The VIN number is: WAULC68E94A238711
Customer reply replied 1 month ago
Unfortunately I pulled each of the fuses out to try to determine which circuit was drawing the battery down.. no trouble codes showed up when I connected the scanner. The scanner showed correct data on the sensors that will lead with the engine off let's where coolant temperature sensor air intake temperature sensor and throttle position sensor and the O2 sensor is reading .458 volts while the engine was off of course. I am going to send you a picture in a few minutes
Customer reply replied 1 month ago
Can you get me a wiring diagram for the fuel pump system?
Customer reply replied 1 month ago
I can't seem to find one online
Customer reply replied 1 month ago
I am off work today if you happen to get a chance to help out that would be great. I realize you may not be off work until tonight. I work tomorrow until 3:30 p.m.
Customer reply replied 1 month ago
Did I lose you? Please communicate
Audi Mechanic: David Craig, Auto Mechanic replied 1 month ago
David Craig
David Craig, Auto Mechanic
Category: Audi
Satisfied Customers: 4,735
Experience: Owner/Mechanic at 3D Automotive
Verified

Hi I'm David, if the battery is dropping below 9.8 VDC, the starter is drawing too many amps.

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Customer reply replied 1 month ago
When I remove 2nd lug off the positive battery terminal (which is apparently called the main fuse) then the voltage does not drop below 10.5 volts
Audi Mechanic: David Craig, Auto Mechanic replied 1 month ago

ok, ill open this up to the others

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Customer reply replied 1 month ago
Where you able to see the photograph of the main fuse that I attached in my previous comments
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago
Wolfgang
Wolfgang, Audi master tech
Category: Audi
Satisfied Customers: 4,978
Experience: Senior Audi Master Tech 15 yrs
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Welcome, I'm Wolfgang.

  • WORK TIME, I am here 7 days a week but not all hours of the day, do not worry I will respond.
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  • RATING ANSWERS, please let me know what you need from me so you are pleased with my answer.

The last person has dropped out but lets get to the bottom of this!!

I need a photograph of the options sticker in the spare tire area. it is 3x5 in size , white and has the vin # on it . I need this info to get the factory information and wiring diagrams to assist. you have a voltage drop and need to isolate the location of the drop!!

Thanks Gary

Wolfgang

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Customer reply replied 1 month ago
I'll take photo for you after Lockheed Martin today ....after 430pm MST...
Thanks Wolfgang!
Customer reply replied 1 month ago
After work today...
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

got it thanks!

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Customer reply replied 1 month ago
Wolfgang, sorry for delay on photo of sticker... I'll get it today..
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

Thanks for the update!!

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Customer reply replied 1 month ago
Wolfgang I purchased the Bentley manual and I should have it in the morning. I purchased a subscription for alldatadiy.com also which has wiring diagrams.
Customer reply replied 1 month ago
My login is Customer and my password ***** ***** if you would like to go look at the diagrams
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

yes it is !!!

no i have the factory ones from Audi which i know they are the correct !! let me get them up!!

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Customer reply replied 1 month ago
I can check it in the morning
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

got it!!

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Customer reply replied 1 month ago
I do have 12 volts at that point except when the engine is cranking it drops down to about 8 volts
Customer reply replied 1 month ago
I've got a big draw coming from the main use cable Where It Bolts to the battery cable. When I take that cable off and touch it to the battery it's Parts pretty good and if I touch my multimeter from that main fuse cable to the positive battery cable it gives me a full 12 volts
Customer reply replied 1 month ago
When I am cranking the battery voltage drops to 8 volts
Customer reply replied 1 month ago
The battery was dead almost completely this morning which tells me that dry is happening even when the starter is not cranking.
Customer reply replied 1 month ago
I disconnected of the connections at the alternator and the main fuse cable still Sparks and has a pretty good short to ground still
Customer reply replied 1 month ago
I am wondering about disconnecting the cable to the starter to see if the starter might be sorted out to ground. I tried another battery just in case the battery was shorted out internally. But I had the same problem with new battery
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago
Do you have an inductive amp clamp to measure the drain ?
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Customer reply replied 1 month ago
No I do not have an inductive clamp.
Customer reply replied 1 month ago
What do you think about me locating connector 501 with the round circle on the diagram and disconnecting one circuit at a time or all of them at first 2 try to determine where the draw is coming from?
Customer reply replied 1 month ago
Actually I believe 501 is more of a junction block then connector
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago
The 501 is the main feed to the relay plate. The plate where the fuel pump relay is located that is the plate and threaded in the bottom.
Honestly let me ask you thisDo you have a scan tool ? Vag com preferred to scan all modules.
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Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago
Also when you turn on the key does the check engine light up in the dash?
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Customer reply replied 1 month ago
I have a generic scan tool
Customer reply replied 1 month ago
I will look for the check engine light
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago
Use what u have and check for the light
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Customer reply replied 1 month ago
Unfortunately I did not check the codes immediately when I started this job and now they have all been cleared. The check engine light does come on the dashboard when I turn the key on
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago
What happens if you place 12v at the pump and crank does the engine run? External 12 volts
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Customer reply replied 1 month ago
It runs for a few seconds then it dies and I think that is because it is only getting 8 and a half volts to the ECM fuse number 34
Customer reply replied 1 month ago
I have isolated every circuit coming off of the main fuse from the battery except I cannot figure out how to disconnect or even locate a32 connector 30 pin connector
Customer reply replied 1 month ago
This car does not have a S9 fuse it is a blank hole but I have disconnected the S14 fuse. Wouldn't you agree that should isolate those circuits so I don't have to disconnect A52 or A57 connectors
Customer reply replied 1 month ago
It shows that it should have an S9 fuse but then I saw an asterik that said that was for automatic transmission only
Customer reply replied 1 month ago
I am isolating each circuit one at a time until the main fuse cable doesn't start when I touch it to the positive battery post.
Customer reply replied 1 month ago
The word start should have been Spark
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

no I have asked specifically use a 12 outside source from the vehicle to the fuel pump and start and run the vehicle does it run continuously for 3 minutes minimum!!

the reason is this if you let the vehicle run enough it may set codes in the modules to scan!!

you cannot go by just spark on diagnosis!!

Please help me to help you and do the tests exactly what i have asked for!!

thanks

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Customer reply replied 1 month ago
I don't think I will be able to get this car to run for 3 minutes or more because short is effecting voltage to the computer because the fuel pump relay voltage to the ECU fuse and the fuel pump fuse... but I will try again tomorrow and let you know I can get any trouble codes
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

please do!! thanks

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Customer reply replied 1 month ago
Sorry for delay it's been cold cold and snowy and I'm working outside. I could not get the car to start. I pulled a spark plug and it looked black and was wet with fuel. For some reason the fuel pump runs now and the voltage is 12v now.. the engine sounds like it might start but it doesn't so I am going to put new spark plugs in tomorrow and see if it will start. It seems to crank good and fast now also. Tomorrow hopefully it will start and I can check for trouble codes
Audi Mechanic: Wolfgang, Audi master tech replied 1 month ago

blow the cylinders with air to dry up and then squirt little oil in the cylinders to lube the rings for compression before installing the new plugs

being flooded i wonder if the coolant temp sensor is reading correctly!!

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Customer reply replied 28 days ago
The car will still not start even after changing the spark plugs. With the scanner hooked up and the engine not running of course coolant temperature sensor seems to be matching the ambient temperature. If I turn the engine over with the starter it will sounds like it's about to start but then it goes away if I continue to crank the starter. I have discovered if I stop cranking just a second after it tries to start and then I wait turn the key completely off and do it again it eventually runs for a few more seconds each time and eventually I can give it to gas and run it up to about 2,000 RPMs for about 3 seconds before it just dies back down as if the fuel pump quit pumping.
Customer reply replied 28 days ago
I noticed something peculiar while the scanner was hooked up. The load percentage read 75.3 [LOAD_PCT(%)]
Audi Mechanic: Wolfgang, Audi master tech replied 28 days ago
Unhook mass air flow sensor and retry starting vehicle
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