Nvncibl

Guys,

Tonight I had my fuel pump cover removed ,the FP plug pulled out and a multi-meter plugged into leads 1 and 4, like my Bentley instructions say. When I turn the key, I don't see any voltage until I turn it all the way to start. Then it only briefly hits 11.8/11.9 volts and goes back down. After pulling out the FP and testing it with 12 volts ran directly to it, it seems like its working but i only ran it for a quick second because it was almost dry and I didn't want to fry it.

Now, as I type this, I realized that I was using a portable battery jumper for my 12 volt source, due to my car battery being VERY dead from sitting for too long w/o running. The jumper box was pretty well charged. Could that be the reason for the lack of constant 12 volts back at the FP plug or is there something I'm missing. Ignition switch going bad, maybe??


I searched but couldn't find this topic answered exactly -

egp320i

A fully charged battery will be 12.8 but that is not what you will see due to fuses and regulators/relays.
12v +/- .01 should be fine.

FP are fairly tired by 100K, if the miles are around that realm it's due to fail even if it's running fine.

Nvncibl

Thanks for the info egp320i. Its an OEM FP but I have no idea if it's ever been replaced. I guess I'll keep troubleshooting the voltage after I put the battery back in today. Its been charging all night and is looking good. One sign I had that suggested a weakening FP, before the car stopped running, was that the car took a long time to actually fire up. It would turn over for as long as 10 seconds sometimes before starting up. Does that sound like a FP or maybe the fuel pressure reg or the filter. Maybe its a combination of things.

04A41.8T_CVT

Did you problem get solved? I am guessing it was the ignition switch.

x19

I have a confusing to your problems, When do the Diagnosing of Electric problem,you have to have a good condition of battery first. and you have a starting problem ( with fuel pump itself and(or) fuel pressure) with fuel pump
pressure tester on) etc.

You hooked up the fuel pump pressure gauge in the system and when you clamp the return hose momentary. You will see the high pressure,more than normal pressure(Re, if normal press. 28 psi and 7~80psi this pressure shows your pump a still healthy condition. Good luck and I hope you already fix the all problem. Happy Holidays to all. x19

egp320i

Of the 3 Audi's I own the fuel pumps died not long after 100K. If you have over that and have no records of it being changed then it's simply due sooner then later.

Least my external pump died in a parking lot and not on the freeway or somewhere worse.
My internal died in my driveway.