Vacuum Hose / FPR & HVAC ('90 L98)

[Spinman]

Just finished replacing my injectors and reassembling the engine.


Have a question on the vaccum hose for the FPR.

I see that there are 3 vacuum port on plenum, near the sensor that is mounted on the rear passenger side. The rear port has a hose running directly to the sensor (I never needed to remove).

That leaves 2 open ports (center and front). Which port does the line from the FPR attach to? The bend on the front port seems a little tight - so I am guessing that the middle port is the correct option (and presumably does not make a difference, vacuum is vacuum).

And finally, I must be missing a hose - what attaches to the 3rd (presumably front) port? BTW - my HVAC now blows only on the floor and defroster (default), so it would appear that I am missing a vacuum line for the HVAC system. I see that there is a pre-formed vacuum line running to a "T" on the drivers side of the firewall - and disappears under the fuel rail. Looks like I've pinched it under the rail. Rather than unbolting and freeing the line, perhaps it would be easier to just replace it. Does this hose then mount in the front vacuum port?

Thanks -

 

[Hrtbeat1]

There should be a little vaccuum line that goes from one of the two remaining ports to the FPR. The other vaccuum port goes to the return for the Cruise Control. Look closely around the distributor, it sometimes will fall and find its way under the distributor. About 8 inches the vaccuum fitting goes to a solenoid / diverter / switch that sits right under where the connections to the distributor are.

 

[Hrtbeat1]

The other end of the switch / diverter / solenoid goes back into the wiring harness and into the cabin so I would guess that this end goes to the HVAC.

 

[Spinman]

Problem solved - ended up removing the plenum and unbolting the fuel rail so that I could access the vacuum hose that I had inadverently pinched under the rail.

Thanks -