1989 Chevy Blazer Engine stumbles

Tiny
PAULNC57
  • MEMBER
  • 1989 CHEVROLET BLAZER
Engine Performance problem
1989 Chevy Blazer

Vehicle runs fine most of the time but suddenly will start stumbling (like suddenly lean mixture. Includes the occassional backfire in carb). I have changed the fuel filter (it acts like a dirty fuel filter) but problem will suddenly appear even now. Suggestions?
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Sunday, January 24th, 2010 AT 12:01 AM

3 Replies

Tiny
RASMATAZ
  • MEMBER
Check and test all the following listed below:

Oygen sensor
Dirty fuel injectors (cleaning the injectors often fixes this).
Bad MAP (manifold absolute pressure) sensor
Bad TPS (throttle position) sensor
Bad or dirty MAF (mass airflow) sensor
Low fuel pressure (leaky fuel pressure regulator or weak fuel pump)
Vacuum leaks (intake manifold, vacuum hoses, throttle body, EGR valve)
Bad gasoline (fuel contaminated with water or too much alcohol)

Sometimes, what feels like a hesitation is actually ignition misfire rather than lean misfire. The causes of ignition misfire may include:

Dirty or worn spark plugs
Bad plug wires
Weak ignition coil
Wet plug wires
Cap and rotor

Note: If it doesn't apply disregard.
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Sunday, January 24th, 2010 AT 12:09 AM
Tiny
PAULNC57
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One thing became clear today when I drove it (it's
girlfriends vehicle so I had only driven it briefly before). When you start out on the road it runs fine. Real good in fact. After about 10-15 minutes when it has warmed up is when the issues begin. Then after cutting it off and letting it cool for 20 minutes, it was still too warm. I cranked it up again and same problem. Seems a COLD start and run it works fine but after warm up, problems! Oh, also, at one point I really put my foot into it and it hesitated and backfired but continued running. Tried it again and it didn't backfire again. How should I proceed. Checking what in which priority (from most likely to less likely)?
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Sunday, January 24th, 2010 AT 4:25 PM
Tiny
RASMATAZ
  • MEMBER
Check the fuel pressure with a fuel pressure gauge, test the throttle position sensor and manifold absolute pressure sensor-also test the ignition coil
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Sunday, January 24th, 2010 AT 5:34 PM

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