This relates to the 1994 LT1 out of a Buick Roadmaster in my 1992 SJSC. I noticed that the lower of the 2 vacuum hoses pictured is not connected to anything and is not blocked off. This may be the/a reason for my high idle. Anyone tell me where it is/was supposed to go and what it did?
I have a similar engine in my car.
Can not tell from the pictures.
Is it a vacum hose or something else? Put a guage on it or just feel the tip!
Does blockig it change the idle speed?
Might be the vent for the OPTIspark
Carl, I was just at the wrecking yard and they had a 95 Buick Roadmaster. Had the same setup of two vacuum fittings, one beneath the other. The lower hose has some kind of check valve, but it was cut off so I couldn’t tell where it went. I’m certain it is a vacuum hose. When I am able to trace the electrical no start issue, I will determine if there is actually vacuum at the tip.
I happened to find the following post on the LT1 forum: “There’s 2 small vacuum fittings on the pass. side of the intake, just aft of the EVAP purge solenoid. top one goes to a small check valve for the HVAC, bottom one should go to the FPR. top/bottom arrangement of these 2 is not important, but yes, you need vacuum to make the FPR’s diaphragm work correctly. Sounds like you got the HVAC check valve hooked up but not the FPR.” I believe in my picture, the top vacuum hose does go the the Fuel Pressure Regulator. If the quote is correct, the other one, which does have a check valve, would go to somewhere in the HVAC system. Until I can figure that out, I will just block it off.