# Possible vacuum leak and has misfire **URL:** \ **Category:** Maintenance/Repairs\ **Tags:** sierra-1500, gmc\ **Created:** [July 18, 2019, 5:54pm UTC](https://community.cartalk.com/t/possible-vacuum-leak-and-has-misfire/144703 "2019-07-18T17:54:08Z")\ **Posts on this page:** 3\ **Page:** 1
**Author:** ![Trent\_Risley](https://avatars.discourse-cdn.com/v4/letter/t/ea666f/32.png) [@Trent\_Risley](https://community.cartalk.com/u/Trent_Risley)\ **Post date:** [July 18, 2019, 5:54pm UTC](https://community.cartalk.com/t/possible-vacuum-leak-and-has-misfire/144703/1 "2019-07-18T17:54:08Z")
I got a 2000 gmc sierra 1500 5.3 v8. about 8 months ago it had some brake problems and i fixed them. new lines,calipers, pads, rotors and brake master cylinder. recently the trucks brakes went again and the truck is very choppy. i replaced the brake booster yesterday and right after installation the pedal was harder and truck wouldn’t shift at all. so installed a new brake light switch and i am able to shift now. brake pedal went down a little bit but is still horrible and hardly stops at even 5mph. any thing can help i thought it must be a vacuum leak but i can’t figure it out ---
**Author:** ![Barkydog](https://sea1.discourse-cdn.com/cartalk/user_avatar/community.cartalk.com/barkydog/32/2470_2.png) [@Barkydog](https://community.cartalk.com/u/Barkydog)\ **Post date:** [July 18, 2019, 6:04pm UTC](https://community.cartalk.com/t/possible-vacuum-leak-and-has-misfire/144703/2 "2019-07-18T18:04:44Z")
Is there a vacuum hose to the booster, maybe it is the culprit. ---
**Author:** ![Trent\_Risley](https://avatars.discourse-cdn.com/v4/letter/t/ea666f/32.png) [@Trent\_Risley](https://community.cartalk.com/u/Trent_Risley)\ **Post date:** [July 18, 2019, 6:20pm UTC](https://community.cartalk.com/t/possible-vacuum-leak-and-has-misfire/144703/3 "2019-07-18T18:20:22Z")
the hose is good