Car cranks but won't start, fuel pump relay ticking repeatedly

[hitrun222]

Hi all, thanks for reading and helping.

2001 A6 2.7T 6 speed, 197k
Yesterday morning car didn't start first key turn, which is strange for it, but started hesitantly almost like it wasn't getting enough fuel or something with the second attempt. It drove the 20 miles to work just fine and started up just fine 8 hours later, drove the 20 miles back and made another short trip for food shortly after, also fine.

This afternoon it cranks but won't start and something is ticking under the dash. The fuel pump relay is what's ticking I discover, after taking the trim off and feeling it to confirm, and doing some reading in the forums. Checked the fuses, all fine. Pulled the back seat up and checked the fuel pump wiring and plugs for any damage or corrosion, all fine. Had someone try to start the car as I listen to the fuel pump, I can hear a quiet whiring, had to have my hear close to hear, from it while cranking so guessed it was ok. Is it, should it be louder? Replaced the fuel pump relay, because it was cheap at the parts store, but still have the same problem. Also thought maybe a plugged fuel filter? I haven't changed it in the 6 years I've had the car, just didn't think to, and I don't know if it was changed by the previous owner. Fuel gauge showed just over 1/8 tank. The car has been relatively problem free for me with just basic maintenance in the driveway the last few years.

Thoughts anyone? Thank you!

[MrWalker]

hey not the most experienced with most things with cars but if it were me i would start by changing the fuel filter. if its clogged really good it will prevent the fuel from passing. not sure how long you should change the filter but 6 years seems like it would be a good time lol. good luck.

[hitrun222]

So I've changed the fuel filter, it was cheap and I figured why not, didn't help. Can't say I'm surprised, but hey, worth a shot.
Only codes I got from a regular OBD2 scanner are for an O2 sensor, bank 2 sensor 2, which had been showing open circuit for a long while but now also says no activity for said sensor.

[AWTA]

So I've changed the fuel filter, it was cheap and I figured why not, didn't help. Can't say I'm surprised, but hey, worth a shot.
Only codes I got from a regular OBD2 scanner are for an O2 sensor, bank 2 sensor 2, which had been showing open circuit for a long while but now also says no activity for said sensor.

What a coincidence, but this is the exact same issue that I'm having. Ticking and everything. I've posted my issue as well and still working on it. I also plan to change the fuel filter, see what happens. Bizzare. I'll keep you posted if I come up with anything.

[carmudgeon]

It's most likely the fuel pump but there's only so much you can diagnose without the proper tools. Check the fuel pressure at the rail with the ignition on. Other than that get the meter out and start checking the pump.

[hitrun222]

For some reason I keep thinking fuel pump too, but I want to be sure before I spend the money for one. How and where would I check the fuel pressure? I looked all over the fuel rail but didn't see an access, other than pulling a hose off it I'd guess? Even then, what would I need to test it? Tried checking voltage at fuel pump plug, but my meter is cheap garbage and I don't trust it, but there were voltage readings at least.
Tried listening to the pump while cranking and key on and I can just kinda hear it with my ear next to it, but I sadly can't remember how loud it used to be or if I could even hear it at all. Maybe it's just partly died and can't pressurize enough?

[Kaane]

Scan for codes. Bad engine coolant sensor will make the car hard to start.

[hitrun222]

Posted that yesterday, only 2 codes were for a bad O2 sensor bank 2 sensor 2, open circuit and no activity. The open circuit has been like that for quite a while now, the no activity is new. These were also pulled with a different scanner than usual, the usual did have a code that didn't match in the bentley manual that numerically I think would have put it with that sensor as well though. Hasn't been an issue with it running before. I will be replacing it soon now that work has picked up, but unless it's related it'll be a few weeks before I'll have the money for it depending on what it takes to get it running now. As far as coolant sensor, only thing I do know is it has the updated green one.

[iandonovan]

I'm having the exact same problem... let me know what happens...

[AWTA]

Just to update. I changed my fuel filter which was original, 2001, and it seems to have solved my issue. Perhaps the pump is getting weak and the clogged filter was just enough to restrict the flow of gas to starve the engine.

Honestly, it doesn't seem probable but it's worked so far and I'm going with it. I'll updated if the problem arises again.

[MrWalker]

Just to update. I changed my fuel filter which was original, 2001, and it seems to have solved my issue. Perhaps the pump is getting weak and the clogged filter was just enough to restrict the flow of gas to starve the engine.

Honestly, it doesn't seem probable but it's worked so far and I'm going with it. I'll updated if the problem arises again.

Hey glad everything worked out. Sometimes we neglect the small things without even knowing it. These cars are maintenance maintenance maintenance. At least mine seems to be.