my 1990 240 wagon was suffering fuel supply issues after i changed out the fuel filter against the advice of my volvo expert friend. the filter appeared to be original and if it was it had had 230k worth of fuel run through it so a renewal sounded like a good idea. filter change went fine, but about a week later i started to have rough idling symptoms and the main fuel pump was making dry raspy noises. i ASSUMED that i had disturbed some deposits in the main fuel pump when i did the filter, so i poured some techtron into the gas to see if that would clean out the pump and restore it. nope. i pulled out the rear carpet and opened up the tank sender access panel and listened to the sender unit. sounded ok. so i ASSUMED the main pump needed replacement. did that. could still hear the main pump starving for fuel. well, i ASSUMED, prehaps the sender pump was the problem. the top was looking pretty rusty anyway so i changed that out. nope. still hearing awful sounds from the main pump and the car was stalling out after about 2 minutes of idling. took the rest of the day off to think peacful thoughts and clean the guns. checked out the fuel pump relay and fuses, all fine. fine, fine. finally we tried swapping out the fuel line pressure regulator. TA-DA! paydirt.we hacksawed the bad one open, it had caught some sediment i ASSUME from the filter change. kinda obvious in hindsight when you see how small the fuel passage is in the regulator.

SO IF YOU CHANGE OUT A FUEL FILTER AND GET PROBLEMS CHECK OUT THE PRESSURE REGULATOR FIRST! would have saved 270 bucks worth of parts, 6-8 hours labor. now ive got a crappy aftermarket main fuel pump (timebomb)in my wagon. alas.

hopefully somebody can learn from my folly.