My 95 850 turbo 2.3L cranks over, catches once but never starts. Doesn't matter if I don't touch the gas (normal way I start it) or pump or hold it to the floor. Checked the fuel pressure - okay at 44 psi. When I turn the key off I here a slight mechanical noise coming from under where the throttle drum pivots and feel vibration for awhile until it shuts off in 30-60seconds. Any ideas?

 

Maybe the Cam Shaft Sensor. https://volvoforums.com/forum/volvo-850-16/93-850-wont-start-34074/

 

the mechanical noise you hear is the AIS mine does that, are everything plugged in? is your intercooler piping hooked up?

 

Thanks. What's the AIS? Everything is plugged in. I added another link after investigating it some more. I think the throttle is locked open irrespective if I pump it or not.

https://volvoforums.com/forum/volvo-850-16/95-850-turbo-throttle-revs-up-itself-41079/

 

the AIS is i believe the air/automatic idle sensor it pushes air in when the throttle is closed to keep the engine idling. so your tps is failing? do you have a vaccuum leak?

 

Don't know if its tps or vacuum. Would that make it go from idle to 3500 rpm on its own? Would seem like a big vacuum leak to do that instantly.

 

yeah or a bad tps maybe egr