1998 S90 slight hesitation

anbran1 · Post by **anbran1** » 23 Oct 2013, 12:44

My car recently, on occasion, would hesitate on acceleration from a stopped position...Almost like it has no fuel for a sec...then off I go with no problem a moment later.
I am showing a P0440 OBD2 code...
I also notice lately that I have either a positive or negative "pressure" when I release the fuel filler cap...
(It never used to do this) (It's hard to determine whether it's + or - pressure.

Also...when I shut the car off, I hear a light clicking noise...then I go and release the fuel cap...and the clicking stops...

Is this some sort of venting EVAP thing going on?!

anbran1 · Post by **anbran1** » 24 Oct 2013, 09:10

Decided to check the Evaporative purge valve....I removed it and noticed that I can blow air through it with no restrictions...(Don't think it's supposed to do that?!) I have an extra identical one...and I cannot blow air through it...so I figured this extra one is operative?!?!

Thoughts?

lindy8_man · Post by **lindy8_man** » 25 Oct 2013, 17:58

Evap problem for sure. I would also replace your gas cap. look for cracked and erroded rubber connectors.

anbran1 · Post by **anbran1** » 25 Oct 2013, 19:23

No more hesitation...and no more "sucking" sound when I remove the gas cap! I'm assuming the old evap purge valve, being stuck open all the time, continuously drew fumes out of the tank and straight into the intake manifold without any valve control and signals from the ECM...

So far so good anyway!

lindy8_man · Post by **lindy8_man** » 26 Oct 2013, 13:07

You will probably get better mileage now!