I was tinkering with my Formula's stereo yesterday and after running the stereo with the car off for a while I started the car to prevent draining the battery. After I finished what I was doing I shut the car off and noticed the fuel pressure slowly started to drop. This wasn't happening before I installed an SLP CAI and relocated the evap canister beneath the passenger side headlight just over a week ago. Could the relocation be causing venting problems (I had to lengthen the lines to the can)? I have one of those "POS" Holley afprs and that was the first thing I checked but no leaking out the vacuum line. My pump is a Walbro 190lph with a Racetronix hotwire kit and was installed back in November with the TPI swap. The TPI is stock with only an airfoil, the regulator and a PROM adapter from TPIParts.com to disable the AIR,A/C, speed and rev limiters and to correct for the 22# injectors that came with the TPI. The injectors are the only old part of the fuel system, could they be the problem. Also the pressure drop only occurred once, after 3 more restarts with no pressure drop I listed it as a fluke but I'm still concerned. The pump pressurizes up to where it's supposed to and the car runs just like it should with no issues. Anyone have this happen and if so what was the reason?

 

Not something I see to great of a concern for. My tpi cars have seem to do this before as well. Many times if you have a new or upgraded fuel pump the culprit is the the fpr. The regualtor is what controls the bleed back to the tank. it should slowly bleed back but if you have a fast drain back your regulator might not be holding fuel pressure in the rails like it is supposed to. Mine did this more when i had my holley stealth ram first installed with the pos stock regualtor they give for it.