1991 Nissan Truck fuel issue

Tiny
TIMPRO
  • MEMBER
  • 1991 NISSAN TRUCK
  • 4 CYL
  • 2WD
  • MANUAL
  • 220,000 MILES
My truck is idling fine, but when I rev it to 2000 rpm's, it starts to hesitat, seems like it is getting to much fuel or not enough. I've changed the fuel filter, and the o2 sensor beside the manifold. Is there another os sensor on the vehicle? Also what should I check next?
Sunday, August 9th, 2009 AT 4:12 PM

1 Reply

Tiny
RASMATAZ
  • MECHANIC
  • 75,992 POSTS
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
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Sunday, August 9th, 2009 AT 4:15 PM

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