Local2Ed

I'm putting injectors in my 1985 Corvette and as I removed the plenum I found what may have been a disconected vacuum line.
The line in question comes off the bottom of the throttle body at the "t"and points toward the passenger side. The underhood vacuum diagram looks like it goes to the EGR solenoid but I find nothing on the solenoid vacuum connector that looks like a line is missing.

I did the search here and the few pictures of vacuum diagrams I seen were for a 1986 and appear to route differently than a 1985.

I also looked in the FSM and can't find anything at all about this line.

Thanks

Local2Ed

I think the vacuum lines that are on the two ports on the passenger side rear plenum have been mixed up by the PO. On the diagram it shows the rear port for HVAC. I'm trying to find which hose is for the HVAC right now. I think the 3 port check valve is not connected correctly.
I'm still searching for some pictures of how this is routed correctly.
Looks like everything is there just may not be going to the right places.

Cliff Harris

The EGR solenoid was moved to the rear bolt of the thermostat housing in 1986, which is why the vacuum routing diagrams are different. In 1985 it's mounted on the rear of the intake manifold on the passenger side. The input vacuum for it comes from the ported vacuum port on the bottom of the throttle body. After going through the EGR solenoid, it connects to the EGR valve.

The rear vacuum port on the rear of the plenum goes to the the vacuum check valve. The front vacuum port goes to the A.I.R. solenoids and the fuel pressure regulator. My '86 has this wonderful "vacuum harness" that takes care of all this:

Local2Ed

Thanks Cliff. After going over many threads last night I then understood that the previous owner mixed up the vacuum lines for the EGR solenoid/hvac/cruise control. Maybe now my cruise will work after I remove it from the EGR solenoid where I found out in another thread, that no line should even be hooked there.

I lucked out that the line from under the throttle body was laying open under the plenum by the FPR otherwise I may not have discovered the vacuum lines were not in the correct place until I started troubleshooting the cruise control.

Joe C

on an 85 corvette, there are two (2) vacuum lines coming off the EGR solenoid - at the aft port, one line goes directly to the EGR valve itself, and the other line, the front port, goes to the "tee" under the throttle body. the EGR solenoid is mounted to the aft RH intake manifold - it's a one year configuration.

Local2Ed

Finished installing the Bosch III's from FIC and noticed a huge improvement in idle and driveability. In case anybody else needs this answered, yes, the plastic disc surrounding the nozzle that goes into the intake manifold does stay on, on these injectors. I thought it was a dumb question but when I called FIC to confirm it the gentleman I spoke to said that's a common question they get.

As a added bonus my cruise control seems to be working now that I hooked up the vacuum lines correctly.

Thanks for the help.

Joe C

question - does the "blue" boschIIIs have the secondary O-ring that limits the depth the injector goes into the intake for the 85 L98? FIC's photos do not show the additional O-ring. I do know the "yellow" boschIII's (86-91 L98's) have this depth limiting O-ring. I've been thinking about upgrading my 85 with boschIII's.

Local2Ed

I don't recall how many O-rings were on the bottom of the injector.
I'm happy with the Bosch III's but then my old injectors leaked so bad I could smell raw fuel when I removed the sparkplugs so I could have put any brand in and seen an improvement.