It is a 305 4BLL carb 1986 IROCZ. I had to replace the water pump last weekend. Ever since then, the car is hard to start and once it does, it will not stay running on idle. I have to keep the pedal pushed in some to keep it running. If it does idle, its real rough and below 500 rpms. I am thinking a vacuum leak and I can hear some type of hissing sound but I cannot locate. Since I will be repping the carb and intake to non ECM control in the near future, can I remove all the vacuum line and block them at the carb to see if that solves the problem? I found a broken line coming off the canister but it looks like it may have been broken for a while or on the verge of breaking. I cannot tell where the other end goes. I have looked and looked. The big one going to tot he carb is intake, this is a 1/4 inch type hose. There is another going to what I believe is fuel line back to the tank but not sure, that one seems fine. I am believing the one that is broken goes on top somewhere. No clue where. I have tried to find it with no luck. I do know that the before I got the car, a lot of things were moved around and or disconnected one way or another so it is very confusing under there. I would like to just remove it all but I was also told that vacuum also controls things up under the dash and do not want to accidently remove them.

 

You don't have to go to the trouble of ripping off and plugging every vacuum line, just try them one at a time starting from the top down. Remove it from the intake or carb, plug the source, and see how it runs. Once the culprit is found, trace those lines to see where you left one disconnected. There are a few that go to the stock air pump and temp switches towards the front of the motor that you may have overlooked or cracked when chaning the water pump.