Rough Idle and spongy Brakes
09-10-2018, 04:58 PM
#1
Rough Idle and spongy Brakes
Hi, I have a 1990 corvette that I have been restoring to its former glory for a few years now. It has 117,000 miles on it with about 4,000 on a engine rebuild and about 2,000 miles on a transmission rebuild. I have been fighting oil leaks for the past few months and have only recently slowed the leak to a manageable drip. I noticed that it has been idling rough for a while now so I went to inspect it and noticed that a few vacuum lines had holes in them so I replaced them. It made my problem only a little better, I noticed that I have a line running from the Vapor canister to absolutely nowhere it runs from the top of the canister,labeled purge, along the side of the wheel well and then stops right underneath the computer that it under the hood, I cannot remember the name of right now. It dies on me if I start it up cold and put it into reverse, and I noticed yesterday that my brakes were incredibly spongy. I have no idea if these two problems are related. Any help would be greatly appreciated.
09-10-2018, 07:46 PM
#2
Zen Vet Master Level VII
Yes, you two symptoms are related as your engine and brakes are both heavily dependant upon vacuum.
Since you recognized that several of your rubber lines are faulty and/or missing, I'd suggest you get a chart and double check your hoses replacing anything suspect.
Since you recognized that several of your rubber lines are faulty and/or missing, I'd suggest you get a chart and double check your hoses replacing anything suspect.
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Ljense (09-10-2018)
09-10-2018, 07:56 PM
#3
Thank you for responding, I replaced about 7 hoses yesterday, but still no fix for it, there seems to be a lot of dark black residue all over where the charcoal vacuum canister is, but the way the vacuum hoses are run makes little sense to me, as the hoses run from the canister itself then run to a fuel vapor canister purge control valve, is that supposed to be there? Also the hose that goes to nowhere has no vacuum pressure in it when I fire up the car. Could my canister have gone bad?
09-11-2018, 07:33 PM
#4
Zen Vet Master Level VII
The black residue on the outside of the canister will have little to due with the operation.Do you have a Field Service Manual (FSM) as that will show you a vacuum hose routing diagram.
09-11-2018, 07:52 PM
#5
I do, for a 1988, as it was the one i owned before hand, it says that the hose is to go to the fuel tank, from my understanding, but i have yet to find anywhere for it to attach