A few weeks ago I posted some questions about problems with rough idle on my
940 turbo.Solved!
It was the fuel pump. This model has only one fuel pump, located in the fuel tank. The older models had two pumps. One feeding pump in the fuel tank, and one high pressure pump underneath the car (under he drivers seat).
No fuel pressure in the system, so it had to be the pump or something in the pump control system. The control system worked all fine, and I had the correct voltage for 2 sec at the pump when trying to start. So the pump was the only possible problem. After a very short inspection of the pump it was no doubth. Totally worn out. The commutator had very deep tracks, and the carbon brushes was totally damaged.
New pump was ordered from a local Volvo dealer. The next day it was connected and ready for testing.
Surprise!... The idle was now ok. No caughs and engine shaking any more.
Costs (Norway): Nkr 2100,- (~ US$ 320,-) (Volvo original pump)