2001 Audi A4 1.8T Quattro

I recently was extremely low on gas. Pulled into the store and came back out to it not starting. The car sounded fine beforehand. I put 3 gallons of gas in. It cranks and sounds like it's about to fire sometimes but never does.

Checked it with VAGCOM got an error for CPS. Replaced it. Still the same thing. Would the next logical step be replacing the fuel filter and then fuel pump?

 

What is a CPS? Crank position sensor or cam position sensor? Also, have you established fuel pressure?

Do some diagnosis before throwing parts at it. That will get expensive

 

Cam position sensor. I have not checked fuel pressure. Is there a guide for that? Is the pump supposed to make any noise when I turn my key forward a notch? Because I had a friend turn it, and put my ear up to the pump in the trunk and heard nothing.

 

So I messed around some more and pulled the fuel pump relay. This is what it looked like https://i.imgur.com/QEqyOg5.jpg All the pins had discoloration on the top and bottom. None of the other relays I pulled looked like this.

 

you are getting a cam position sensor code probably from some thing else. I'd look into the crank position sensor in that case. But before that, ensure the you have some fuel pressure.

The pump doesn't turn on with the key, it only turns on when the car is cranked. Try having your friend crank the car over while you listen to the pump turning on.

 

I'm gonna disagree here. The pump should prime for about a second when the key is turned to the "ON" position, to build fuel pressure prior to cranking.

 

I think sometimes mine does and sometimes it doesn't. like after I put in my walbro pump, I wanted to see if it would prime to make sure I had polarity correct. It would prime with the key on and I thought I have the polarity incorrect. Turns out I just had to crank the car and it turned on. Every other car I have been in primes the pump while the key is "on".

 

This morning I turned the key forward and heard the pump activate. It only did this the first time and each time I would take the key out and try it again, I wouldn't hear it. Not sure if that means it's fully functional or what but I don't have a tool required to test the fuel pressure, but I cranked the engine a few times and popped off the fuel line and it only trickled out. Shouldn't there be some built up pressure from cranking the engine if the pump is working correctly? Another possibility could be a clogged fuel filter causing low pressure? The car has 117k on it and I'm the second owner. No idea if the fuel filter has ever been changed.

 

i had this the other day when cranking it would start then die, if i had my foot on the accelorater it would go to like 5k rpm but no matter how much i reved after that it wouldnt rev and would die.
I figured it being a block or somert in the fuel line with me running it to low on fuel.
how i gt it to start and clear the block was put it in gear, start the car and let of he clutch straight away, it seemed to sort it, from now il never run low on fuel

 

I'm just going to put my $.02 in. My theory is that when you ran so low on gas, all the crap in your gas tank that has built up over the years was pushed into the fuel line clogging the fuel filter. I would replace the fuel filter, even if it's not the problem, at 117k it is time