SPONSORED LINKS

Backfires

Tiny
STEVE BOOK
  • MEMBER
  • 1999 CHEVROLET BLAZER
  • 4.3L
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 100,000 MILES
Truck backfires the PCV sometimes on starting, but
runs perfectly after resetting PCV cap.
Friday, November 18th, 2016 AT 10:48 AM

7 Replies

Tiny
JIS001
  • MECHANIC
  • 3,411 POSTS
Do you have the correct PCV valve installed? Also have you tried scanning for codes? I would use a more advance scanner for that rather then the quick small ones.
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
Friday, November 18th, 2016 AT 11:01 AM
Tiny
STEVE BOOK
  • MEMBER
  • 4 POSTS
I have ordered the PCV valve. The only code that shows up is a knock sensor.
Was this
answer
helpful?
Yes
No
Monday, November 21st, 2016 AT 7:36 AM
Tiny
JIS001
  • MECHANIC
  • 3,411 POSTS
Okay, replace the valve and reset the light and let us know if that fixed the problem or if the code returns.
Was this
answer
helpful?
Yes
No
Monday, November 21st, 2016 AT 9:18 AM
Tiny
STEVE BOOK
  • MEMBER
  • 4 POSTS
Replaced the valve, the only code is a knock sensor, an if still backfired.
Was this
answer
helpful?
Yes
No
Friday, November 25th, 2016 AT 7:38 AM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,397 POSTS
Hey Steve,

I backfire could be caused by an leaking intake valve, here is a guide that will explain all reasons for a backfire.

https://www.2carpros.com/articles/engine-backfires-while-running

Please run some tests and get back to us so we can continue helping you.

Best, Ken
SPONSORED LINKS
Was this
answer
helpful?
Yes
No
Saturday, November 26th, 2016 AT 7:14 PM
Tiny
STEVE BOOK
  • MEMBER
  • 4 POSTS
Does anyone know where the gulp valve is located on 1999 blazer?
Was this
answer
helpful?
Yes
No
Wednesday, November 30th, 2016 AT 12:40 PM
Tiny
KEN L
  • MASTER CERTIFIED MECHANIC
  • 48,397 POSTS
If your engine has one it will be near the exhaust manifold on either side.
Was this
answer
helpful?
Yes
No
Wednesday, November 30th, 2016 AT 8:28 PM

Please login or register to post a reply.

Related Engine Backfire Content

How To Fix an Engine Backfire
VIDEO
How To Fix an Engine Backfire
Instructional repair video
Backfire Repair
GUIDE
Backfire Repair
When your engine backfires it can do so in one of two ways. First and the most common way is when the engine is running a small explosion of unburnt fuel is ignited inside...
VIEW MORE

Sponsored links