I posted recently about the vacuum leak dilemma in my 1989 740T causing the air vents to close up on turbo boost.

http://www.brickboard.com/RWD/volvo/1339475/740/760/780/wheres_vacuum_reservoir.html

Well I have traced this problem to a torn end nipple cap on the vacuum reservoir that's located behind the bumper - note: I am NOT referring to the charcoal canister. If you have a front spoiler, you can actually access this vacuum reservoir bottle through the air intake.

I haven't been able to locate a substitute cap since the nearby autoparts store just don't seem to stock a vacuum nipple cap of the required size. A little bit of self-amalgamating silicone tape with RTV silicone was used to patch up the cap.

Anyway, the bigger issue is that I have had at the same time, a frustrating problem with an immediate stall with poor idle when starting the car from cold (warmed the stall doesn't happen). I regularly have to start the car a second time to get it going again, that or carefully rev the engine to 1200rpm to prevent the vehicle from stalling. I have changed the 02 sensor, and even the engine temp sensor (both rather costly parts) in the past to try to fix this problem. And I was just about to change the fuel pressure regulator as well.

But hey, both my problems are now solved! It was a vacuum leak causing the engine to run too lean on start that was causing the stalls all along (what havoc a torn little rubber cap can wreak)

Hope this helps someone trying to diagnose a similar stalling problem.


Regards
Lucast