1994 GMC Jimmy Hesitation

IDAHOBOUND07

MEMBER
1994 GMC JIMMY
6 CYL
4WD
AUTOMATIC
200,000 MILES

My 1994 GMC Jimmy hesitates and sometimes just stalls out. I had the fuel pump pressure tested and the pressure held at 55 while running then just dropped when it was shut off. The mechanic said I need a new fuel pump. I went for a second opinion to another garage and was told it does NOT sound like the fuel pump. BTW I replaced the starter, battery and fuel filter already. Any ideas on what the problem might be? When it does hesitate or stall, if I turn it off and wait a minute and restart it its good for a few more miles, sometime longer or shorter time. HELP!

Saturday, March 28th, 2009 AT 3:04 PM

1 Reply

RASMATAZ

MECHANIC
75,992 POSTS

1994 GMC Jimmy Hesitation

Possible Causes of Engine Hesitating:

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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Saturday, March 28th, 2009 AT 3:11 PM