Need help with 1999 Pontiac Grand Prix 3.8 liter V-6

[phylny]

The engine of our car has been well maintained, yet it randomly stalls - sometimes after driving for 15-20 minutes, sometimes at start-up. We've had it to two repair shops (Pontiac, and a local guy who we trust) and they ran diagnostics without any results - no codes. The local guy drove it with my husband, because he didn't really think there was a problem, and it stalled on him, too.

We've researched the Internet, and the possible problems include a mass air-flow sensor and/or crankshaft location sensor. Tonight my husband disconnected some of the sensors, drove it, and it ran fine. YET earlier today, in the heat, it stalled five times in 20 minutes. The car always eventually restarts - sometimes immediately, sometimes after 15 or more minutes. In addition, the ABS and Traction controls haven't been working in some time.

The frustrating thing is that the mechanics cannot find anything wrong with it. The car has fresh plugs, fresh plug wires, fresh serpentine belt, and the PVC valve was replaced. Although the car has 150K miles on it, it's visually in great shape, and this is the first time we've ever had a problem of this magnitude.

We were going to bring it to one more place, but before we do, I was wondering if anyone here has knowledge that might help us. This 3.8 engine is the same as those in Chevrolet, Oldsmobile, Buick, and Pontiac.

Thanks in advance to anyone who might be able to steer us in the right direction.

[DainBramaged]

1. Fuel pump (submerged in tank) may be the problem

Or you may need the serious injector cleaning done by your friendly GM dealer.

The 3800 has been GREAT engine for decades. Doesn't have intake leak problems like 4.3 and the 3.2. Lots of grunt, still used (updated) in a multitude of GM products.

Have them check fuel pressure. You may be surprised by the results.

Good luck.

Mr. DainWrench signing off.

[phylny]

2. Thank you for your response!! n/t

[FogerRox]

3. right, a problem with the mass air-flow sensor could be it, but

That should have shown up on the computer diagnostic. Basic rule you need spark, fuel, and air for an engine to run. SO fuel pressure fits in that rule perfectly.

[tkmorris]

4. I thought I remembered seeing something like this

So I went and looked for it. The fuel pump could be the problem, as was said before, and another person reported that their problem was with the crankshaft sensor (which you mentioned when disconnected the car ran fine).