I have the most strange of problems with my S90. As a lifelong Volvo owner, I have been able to tackle most all problems encountered. The really fun one was the replacement of the sensor on the distributer plate on my 740 using JB weld and a rivet gun... worked perfectly after that

well...here goes.

for a couple of years my S90 will hestitate and blow black smoke intermittently. It boggs down and then suddenly lurches with a further press on the gas pedal. NOW, HERE IS THE KICKER, It will do this immediately when I fill the Fuel tank. In other words I can induce the problem by simply filling the gas tank.It will start to sputter and spew black smoke right at the gas station. I have hoped that as time went on it would reveal itself as something that actually disables the car. it has not, but it is quite frustrating. the dealer wants $600-1000 dollars to LOOK at it... could be as high as $2000 according to them, but they dont venture a guess (at least not to me)

It will do this for days, or it may go for weeks without a hitch (or immediately on a full tank). No real link to weather, rain or humidity as far as I can tell. Please help?