Question about 1999 Pontiac Grand Prix

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Number 2 injector stays open?

When first started it runs ok, but once it starts to warm up it starts hesitating. it was doing it intermittently. i usually use about 1/4 tank of fuel to get from and to home/work. But yesterday the car ran very crappy and i used more then a 1/4 tank just to get home

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Vehicles have something like a choke for cold starts which allows more fuel for start-up. As the vehicle warm up it automatically adjust.
I would check the (throttle position sensor) and IAC Valve . Did your vehicle throw up a code?. Check engine light blinking.
Warm up the engine, and unplug one at a time and see if there is any change when unpluged. The sensor which do not register a change may be the problem. Both throttle position sensor and IAC valve can be cleaned. The mass air flow sensor is another problem area. Careful with that unit, it can only be cleaned with mass air flow cleaner, read-up and follow direction for that unit.

Posted on Nov 17, 2013

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Try running a couple cans of fuel injector cleaner through the tank-Denny

Posted on Nov 17, 2013

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SOURCE: Grand Am will not start

ignition module is dead easy to replace right on top under the aluminum coil cover

Posted on Jun 08, 2008

SOURCE: engine intermitantly stalls

if this a fuel injected car just check to fuel pressure first.

Posted on Oct 24, 2008

muttandjeff
  • 359 Answers

SOURCE: No power accelerating or going up a hill

HAVE SOMEONE CK THROTTLE POSITION SENSOR AND CATALYTIC CONVERTER MAKE SURE EXHAUST IS CLEAR

Posted on Feb 03, 2009

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SOURCE: Theft sys. light stays on (solid), no fuel to rail, won't start

You can bypass the relay....I have a 2000 grand am gt and had the same problem.

Posted on May 13, 2009

  • 29 Answers

SOURCE: my 2001 Pontiac Aztek's fuel gauge works until

it is one of two things the fuel gauge in the tank is bad or the gauge in the dash is bad...I would check with the dealer to see if they have seen that problem before...they maybe a recall for that problem...

Posted on Nov 18, 2009

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1 Answer

When i start the truck it run ok but as soon as it warms up or get shifted into gear it hesitates like its not getting fuel, an injector is bad maybe a


I would be looking at two things.
1. Vacuum leak. This can cause the hesitation by making the fuel mix too lean.

2. Temperature sensor. If worse when fully warmed up, this can be a cause.

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1994 chevy suburban help


It could be low fuel pressure from a weak pump. A fuel pressure test would find out. When the engine is cold, the computer keeps the injectors open longer-a cold engine needs more gas to run than a warm one. When at normal operating temperature, the computer matches the gas to the incoming air. If you have low fuel pressure against the injectors, that is when you would notice the hesitation. A possibility anyway.
If fuel pressure is good, check for trouble codes. A sensor may be sending the wrong information. Could be the mass air flow sensor-the one that tells the computer how much air is coming in so it can match the right amount of gas for it-through the injector on-time. There it is, your injector pulse width is too narrow. Causes lean running, stumbling, hesitation. Another possibility. Check for codes first.
If not air or gas related (is your air filter clean? And the gas filter been changed in the last 2 or 3 years?), and no codes, and fuel pressure is good, you may have to keep looking for an electrical fault. If it runs good when cold, doesn't seem likely to be a mechanical fault.

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