RWDlifer

So I decided to change my fuel filter. Proper procedure is to disconnect battery, relieve pressure at the shrader valve etc right? I figure I'll leave the batt connected, don't wanna lose my audio settings, took forever to get them just right...and instead of relieving pressure at the shrader, I decided to remove the fuel pump fuse at the rear SAM then start the car. Car promptly dies, meaning system depressurized, and I'm ready to knock this one out. I mean it's a fuel filter, how hard can it be...
So anyway, got the car up on ramps, loosened the underbody cover and started disconnecting lines. At this point I'm quite confident system is pressurized, so I was totally unprepared when I got a faceful of gas from one of the 4 hoses. Good thing I had shades on...
The FF swap is a breeze, I get everything buttoned up and snug. The whole thing takes 20 min...so I'm feeling pretty good. I put the #4 fuse back in the rear SAM, turn the key on -off a couple of times to build up pressure. First crank...nothing. I figure no problem, takes a while to get the fuel in the plumbing. Second crank = nothing. Whatever.
Third crank = sputtering...now we're getting some fuel, almost there..
Fourth crank = More sputtering, really bad idle. Crap. Then the CEL comes on. I dig into the glove box for the Innova, plug it in and there are three misfire codes, cyl 1, 4 and a random misfire. You've got to be kidding me.
Turned the car off and let it sit for a minute. With the ign on, cleared the misfire codes and cranked again....poor idle again feels like it's running on 3 cylinders. The Innova is still connected, and several misfire codes promptly erupt. What have I done.
I take a look under the FF area, no leaks. Pretty sure I got the plumbing right, and the FF is OEM too. I'm stumped. Turned the car off, waited about 5 minutes, restarted. Normal idle. Phew. Figured I'll go for a spirited drive to celebrate...but no bueno...as soon as I rev above 3k rpm, the lumpy shake starts again....more misfires. Crap. I crawl around the block back home, at this point I decide I'm gonna reinstall the old filter. Parked the car, sat there stewing for a bit, then decided to do a TB reset. Maybe that will help. With that done, car started right up, normal idle and took it on a spirited drive with no issues. No more CELs either. No issues on subsequent starts.
I'm still hanging on to the old FF though...at least until I'm sure this new FF is not going to screw me. I still don't know what caused all that!

slammer111

Before running the car after a fuel filter change, my understanding is that one has to insert the key, turn the key to position 2, then remove the key a few times. The fuel system is full of air bubbles from the change, so one has to prime the system again. The car makes a whirring noise for a few seconds when the key is turned to position 2 - this should be fuel pump running for a few seconds, pressurizing the system.

Hopefully you chose an OEM filter. Non-OEM fuel filters are known for causing problems as well, as there are often issues with the internal valves and other bits. This is a known problem for the W203.