2000 gmc jimmy

[patfan]

I have a 2000 jimmy that brakes real hard.You have to push on the brake pedal real hard to get brakes to work.I had the hood up yesterday and had someone push the pedal when they pushed it there was a hissing noise comming from around master cylinder.Now when pushing brake pedal you have to put transmisson out of gear or engine will stall.It also idles unevenly was wondering if anyone would have any ideas of what would be wrong with it.By the way had rear brake line replaced at local garadge just before this happened.Brakes worked fine before when i got it back this problem was there.The guy who did it told me to go someplace that could plug it in to computer to get codes to see what is wrong .Took it in to autozone no codes were found. Abs lite on dash has been on for a month now. Would appreciate any help that could be given

 

[wirelessF]

Leaking brake booster?

 

[Ryan]

Obviously a vacuum leak, but is it constantly making the hissing noise or just when you are applying brake pressure?

 

[patfan]

It only makes noise when brake is applied

 

[rshaw125]

Did you ever solve the hard start on the Diamante???

 

[patfan]

i had the fuel regulator replaced about 3 weeks ago, but haven't let it sit for more than 12 hours yet.So far so good