I'm working on a '94 850. I put a timing belt on it last summer and did some tune up work. The car drove for a few weeks and then was very low on power and would backfire, blowing the oil filler cap off.

I looked at it the other day and the compression is okay (#5 was a little weak, but came up with a little oil). The plugs were black (~500 miles on them), and the vacuum line to the Fuel Pressure Regulator smelled like gas.

Questions:
1) would a bad FPR cause big backfires ?
2) is it possible to replace the FPR without removing the intale manifold ?
3) if so, are there any special tools needed (the car is 40 minutes from home) ?

Thanks

Greg