1993 Chevy S-10 lost of vacume

1993 CHEVROLET S-10
74,000 MILES • 6 CYL • 4WD • AUTOMATIC
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PAT POWERS
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  • 3 POSTS
4.3 w motor I will start the truck up and it runs fine after about 10 min. I start to loss vacume why?once the truck warms up it stops but comes and goes later not as long or as bad. I put a new e.g.r. iack, throdel posisen, pcv uper intake gasket. and am still having the same problem.
Jan 5, 2009 at 1:01 AM
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JDL
  • ✓Experienced Mechanic
  • 16,098 POSTS
If you put a vacuum gage on it, what were the readings at idle and off idle. If you open the throttle and hold it,what does the gage show? At idle is the needle steady, jumping around?


https://images.2carpros.com/forum/automotive_pictures/170934_vacuum_diagram_1.jpg

As far as vacuum lines, I ran across the above diagram.
Jan 5, 2009 at 6:22 AM
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PAT POWERS
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AFTER IT STARTS TO MESS UP THE GAGE BOUNCES BETWEEN 5 AND 10 MORE ON THE LOW END AFTER OPENING THE THROTTLE IT ALMOST GO TO 0 LIKE MAYBE 1OR 2 AND THE IDLE IS UP AND DOWN WHEN HOLDING THE THROTTLE STEADY I ALSO WHAT TO THANK YOU VERY MUCH FOR THE INFO YOu already sent me.
Jan 6, 2009 at 7:03 AM
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JDL
  • ✓Experienced Mechanic
  • 16,098 POSTS
On a snap throttle test, if the vacuum goes to zero and is very slow to rise back to whatever is normal, you may have a clogged exhaust.

This is just generic stuff, if the needle is jumping around it may be a problem with one cylinder, if it is low and steady, it might be a problem that is common to all cylinders. I'd check for vacuum leaks.

You may need to do a cylinder balance test, you might locate a problem cylinder.
Jan 6, 2009 at 7:41 AM
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