Audi 5000 Quattro S - just bought it, driven to property, was sitting for 3 years in Ariaona, won't start. Sparkplugs spark, but gas seems to not have much pressure at the fuel filter; other than the fuel pump, what else should I check/replace?

Most auto parts stores will clear all error codes for free.
Or you can buy a scan tool from them that will let you clearand reset the codes.

turn key but do not start car, listen to see if you can hear fuel pump start up if not its bad if so then try changing the fuel filter. the worst could be ignition modual out.

Does the fuel gage read any higher now that you put fuel in it? If so, It was probably out of gas like you suspected. However, running a vehicle out of gas is extremely ******* fuel pumps. If your fuel pump was worn, with a lot of miles, it is probably toast now.

Did you put stablizer in the gas before storing it? Does the fuel pump run for 2 seconds when the ign is turned ? Have you checked the air cleaner for debris? Do you have spark? You must have air/fuel/spark to start.

I wish I could give you an instant fix, but I can't. Do you have spark? If so then its either your fuel pump or the CPS, crank position sensor. If no spark then it could be your coil.

SPARK PLUG GAP IS .028

this is for a 2.2ltr, what motor do you have?

This solution is 6 months after, so you've probably fixed the car, but here goes anyway.
The fuel system at engine must be free from vacuum leaks, to work.
Replace the hose. You won't hear the pump until the engine turns over....and then there's too much noise to hear it! No gas to motor is usually the fuel pump relay. Pumps don't fail very often.

My 99 Audi A4 2.8 Quattro was havinga problem starting at times. It would idle poor upon start and then it would come up in rpm where it should be. I had hesitation from a start and after coasting for more than 5-8 seconds, the car would shake violently upon acceleration at about 1/3 throttle. I cleaned the Mass Air Flow Sensor. This helped but did not solve all my problems. I then replaced the Mass Air Flor Sensor. Little to no change there ($108.00). Lastly, I replaced the spark plugs. I bought Bosch plugs ($4.82 ea.). This got rid of all the symptoms. I had bad lugs and possibily a dirty MAF!

Check the fuel filter, you may have clogged it when you filled the tank.