Volvo Turbo 1989 Blows Black Smoke

Hi,
My Volvo Turbo began blowing black smoke when I accelerated between 20kph and 60kph and it took my mechanic overall, about 6 weeks to fix the problem.
I want to share my experiences with you all here, so that what happened to me and "the cure" might help someone else with their Volvo car.
Black smoke is unburnt petrol being blown through the engine and out of the exhaust. Between 20kph and 60kph, my Volvo experienced a flat spot on any slight hill, as if the engine was being choked and I could see a black plume of smoke from my exhaust, as I accelerated, when I looked in my rear view mirror. Fuel costs at my petrol station doubled. At speeds above 70kph my Volvo ran normally and the turbo kicked in without any visible problems.
The turbo on my Volvo is oil cooled. I understand there are 2 hoses from the turbo. One for the oil, the other for the petrol. I understand that because the case of my turbo was cracked, if I had continued to drive my car and that cracked turbo housing had not been detected, then it would have eventually exploded, causing severe damage to my motor and probably I would have had to write off my car.
Cure: Firstly the case of the turbo itself was cracked and I had to have the turbo reconditioned. Parts had to be flown in from overseas and the total cost of repairs was around $3,000 including taking off and putting on the turbo and replacing one seal in the gearbox. Reconditioning of the turbo was a specialized job and this was done by a turbo reconditioner who provided a 1 year warranty for the reconditioned turbo.
Reconditioning the turbo did not fix the problem of the black smoke. That was as bad as ever.
An extensive check of my Volvo, under warranty, from the repairs of the turbo, eventually revealed that the petrol pipe from the turbo to the engine was split and when I accelerated, the split opened and this caused the black smoke out of the exhaust. When the split pipe was replaced, the black smoke disappeared and now my Volvo performs again, like the thoroughbred it used to be.
I hope the above helps someone else with their Volvo, isolate similar problems with their turbo.
One of the other faults, which causes smoke, though I'm uncertain if the smoke is blue or black is the PCV valve. If the above split pipe is not the cause for your Volvo, the PCV valve might be a good place to go next.
BigBenn