1999 Pontiac Grand Prix Idle Problems in 1999 Pontiac Grand

JASON1210

MEMBER
1999 PONTIAC GRAND PRIX
6 CYL
FWD
AUTOMATIC
125,000 MILES

Hello,
I have a 1999 Pontiac Grand Prix GT, Engine 3.8 Ltrs V6, 125,000 miles. I noticed that over the past few weeks my car has been making a humming sound. At first the noise was slight, and not that loud. Along with this humming sound, I also noticed that the car was idling at around 700-800 rpms. I also noticed that while at rest made a gargling sound. A few days ago, the humming sound became extremely loud and persistent. After looking under the hood the humming noise seemed to be coming from the fan belt. I tried using some fan belt conditioner but the noise persisted. The idle also rose to about 1000 rpms. The vehicle was in this state for two days. Then, this morning as I was driving the vehicle started cutting off while I was driving. Once I made it home I attempted to start it again and it didn't start. My father said he believed it was an idle sensor, but he's not a mechanic so he said he's not 100% sure. I would like you guys feedback, it would be greatly appreciated!

1 Reply

FACTORYJACK

MECHANIC
4,159 POSTS

The noise, and the running may, or may not be related. Lets concentrate on getting it started. Chances are, you lost one of two things, spark or fuel. A simple first test that would require little tools is to try some starter fluid in the throttle body. We want to see if it fires off of this, if so you lost fuel. If it does not fire, pull a plug wire, or two, and check for spark. You can put a screwdriver in the boot and hold it close to a ground while cranking, to see if there is spark. Don't hold it too far away from ground or you will be the ground, and get a mild shock. See where this gets you, and follow up.