How/where do you measure fuel pressure? SFTA and couldn't find how. Plus other questions...
03-29-2007, 10:24 AM
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How/where do you measure fuel pressure? SFTA and couldn't find how. Plus other questions...
I have a 2000 A4 2.8 30v tip quattro. My car in running in a lean condition. This occurred after a tranny fluid/filter change and a fuel filter change. Laptop also fried when hooking to VAG, but that's possibly another issue.
My fuel pump whines very lightly when full and if tank is near empty, it whines pretty loud. I'm thinking maybe fuel pump is causing my lean condition as car idles fine, it's just any sort of load (like driving over 30 mph) that car has issues. Maybe changing filter and having pump prime was enough stress to cause pump to go out (car has 85,000)? How/where do I check fuel pressure? Is there any pics or diagrams to show me? How hard is it (I know I need a fuel pressure gauage)?
CEL is not on, if you use Autozone OBD, shows no codes, but VAG does show one when running (but not when car not running): P1857, which is bad/faulty ECU or TCU. Replaced MAF and no change.
Any other advice? Thanks so much for all your help!!
My fuel pump whines very lightly when full and if tank is near empty, it whines pretty loud. I'm thinking maybe fuel pump is causing my lean condition as car idles fine, it's just any sort of load (like driving over 30 mph) that car has issues. Maybe changing filter and having pump prime was enough stress to cause pump to go out (car has 85,000)? How/where do I check fuel pressure? Is there any pics or diagrams to show me? How hard is it (I know I need a fuel pressure gauage)?
CEL is not on, if you use Autozone OBD, shows no codes, but VAG does show one when running (but not when car not running): P1857, which is bad/faulty ECU or TCU. Replaced MAF and no change.
Any other advice? Thanks so much for all your help!!
03-29-2007, 11:16 AM
#2
Wow, bummer to hear you're still having those issues
According to Bentley, a fuel pressure guage is connected between fuel supply line and the fuel rail. I guess you have to disconnect the supply line and hook it to one side of the gauge, and then connect the other gauge hose to the rail. The vacuum line for the pressure regulator is also disconnected for the test.
Should be 3.8 - 4.2 bar with the engine idling.
The other test is to check for flow. Unhook the fuel return line and switch on the pump for 15 seconds. With the fuel hose dumping into a calibrated container, you should get around .4 litres in 15 seconds.
Should be 3.8 - 4.2 bar with the engine idling.
The other test is to check for flow. Unhook the fuel return line and switch on the pump for 15 seconds. With the fuel hose dumping into a calibrated container, you should get around .4 litres in 15 seconds.
03-29-2007, 11:22 AM
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Yeah, still having issues. Also, hard to start 1st thing in morning...
Takes about 5 seconds of cranking. Then car stumbles about 10 seconds before finding idle. I can hear the fuel pump when I'm outside of car. Seems louder than it should be.
03-29-2007, 12:27 PM
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I'm going to try to measure fuel flow first, then pressure if I can get a pressure gauge...
If it's bad, I'm going to have to figure out how to empty that tank as I just filled it yesterday!! 
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03-29-2007, 03:48 PM
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How loud should fuel pump be? I can hear mine in the interior of the car and definitley outside!...
Should it be silent? I can hear it whine when I am in the car and up to about 15 mph with windows closed/stereo off/climate control off. It's not real loud, but I can hear it. It's definitely not quiet.
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