1994 940 Turbo Wagon Vaporlock Like Symptoms

talbott357 · Post by **talbott357** » 24 Mar 2013, 16:56

I know this sounds like something from a newbie, but I have owned several 240/740/940 wagons over the years and have figured out most of the quirks Volvo has. But this one has me stumped. It happens mainly when the outside temps are in the low 80's and above. The rpms will drop, the engine will surge and then it dies, and you smell raw fuel. Try to restart and the throttle is unresponsive and the engine stalls again. In a fit of desperation, I removed the fuel cap and there was alot of pressure behind it, enough to hear it and actually have some fuel come out due to the pressure.
I have replaced the coolant sensor, rpm sensor, fuel pressure is good and no engine codes pop up when this happens. Any ideas would be very helpful,
Thanks!

talbott357 · Post by **talbott357** » 12 Apr 2013, 18:49

From the lack of responses, I guess I will try the low pressure pump in the tank, its the only thing I can think of that has not been replaced.

lummert · Post by **lummert** » 12 Apr 2013, 20:19

One thing you didn't mention is how much fuel is in the tank when this happens.

talbott357 · Post by **talbott357** » 12 Apr 2013, 22:31

Does it both full and empty, and intermittent too. It is definitely lower on power compared to when I rebuilt the top end 2 years ago. I checked the timing and that is dead on, no restriction in the exhaust, and external pump and filter are new.