My number 5 cyl is not firing.

1997 GMC JIMMY
157,000 MILES
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RICKYD
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  • 2 POSTS
I have changed the injector, spark plug, cap and rotor, and wire.
I have checked compression and have 125lbs. I took the plug out and it is firing but changed it twice to make sure it wasnt blowing out. I know I have fuel because you can smell it coming out of the exhaust pipe. I sprayed starting fluid around the area to check for vacuum leaks and it doesnt change so there must not be and I cant hear any either. I took the EGR valve out and it moved freely but cleaned it anyway and put it back on. It is still missing and cant figure it out.
Can you help me?
Thanks Rick
Nov 21, 2011 at 11:02 PM
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JACOBANDNICKOLAS
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Rick, what compression is in the other cylinders? Also, is the spark a good hot blue snapping spark? Are you certain the injector for that cylinder is getting power?
Nov 21, 2011 at 11:03 PM
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RICKYD
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I havent checked the other cylinders and yes the plug spark looked good. If it is a weak spark what would cause that? I already changed the cap, rotor, and wire and theres only one coil.
Thanks.
Nov 21, 2011 at 11:24 PM
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JACOBANDNICKOLAS
  • CAR REPAIR CONTRIBUTOR
  • 110,190 POSTS
A weak coil, weak crank sensor... If it is a blue spark, it should be fine. I wonder if the other cylinders are at the same compression. If they different by more than 10%, you will notice a miss.
Nov 22, 2011 at 3:21 AM
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