Pontiac Grand Prix dies every week in the same place

Maintenance/Repairs
1

My 2001 pontiac grand prix decided to die a few weeks ago on the side of the interstate just as i was driving up a rather long stretch of hill. the car acted just like i took my foot off the gas pedal, rpms dropped down to an idle, and as i pulled over to the side, the car died completely. i thought, great, i’m out of gas, my gas gauge has always acted fishy ever since i got the car some 6 years ago, but i recalled filling up not long ago so i thought, well maybe it’s my fuel pump.

so anyways, after sitting for a few seconds, i tried cranking the car back up, which it did, and started, but as soon as i put it in drive, it died again. this happened a few times then i tried running the engine for awhile in park, and it seemed fine. this time when i put it in drive, it didn’t die, and i was on my way. then it died on me again that day on the way home going up another long hill, and i got it running again the same way.

when i got home, everything i could find told me that it must be the fuel pump. so i went to autozone and borrowed a fuel pressure gauge from them and hooked it up where i could watch it while i drove. Sure enough, the next time i drove up that long hill, it lost all its power again, but didn’t die completely this time, it just idled on the side of the road for a while. but, shockingly, the fuel pressure remained constant through the whole thing around 50psi. so when i got home, i pulled out my fuel injectors and cleaned them up and sprayed off the MAF sensor, because i heard that a dirty MAF sensor could do things like that.

but still, sure enough, today it died again on that same hill on the interstate. i can’t figure out why it’s dying on me like this. it actually completely stopped running today, and i got out and had someone try to crank it over for me. the fuel pump could be heard running, and there was gas in the fuel rail, but i couldn’t tell if the injectors were working. What would that have anything to do with going up a hill? i couldn’t get it going again today. it would start for a second and then die. finally, the battery died, and i had to get it towed home, but sure enough, when i got the battery charged back up, the car started right up like nothing had gone wrong. What is wrong with this car?

2

I would think the same as you that the fuel pump was bad but you have pretty much proved that isn’t the case. I then would check the fuel pressure regulator for a problem.

3

That’s Quite A Detailed Description.
I Don’t See Anything About CEL (Check Engine Light) Illumination Or DTCs (Diagnostic Trouble Codes.)

I’m pretty sure you would have included any discussion of this in your post if that information was available, but it could help to know for sure whether these were present or not during these episodes. Certain failures would likely trigger a CEL and DTCs and other events, not so much.

Am I correct in believing that there has been no CEL on and no DTCs stored ?

CSA

4

The CEL has been on since i bought the car and they assured me that it was a from a catalytic converter that they replaced. The car has had a slight leak in the radiator overflow jug for a few years and i have to top off the radiator every now and again but it has never overheated, in fact it seems like it takes a while to heat up and often the gauge is just above the coldest position. I did bring the car to autozone last week and had them plug it in and they told me that the only code on it was about the engine running at low temperatures and suggested changing the thermostat and temperature sensor.

5

Well, what was the problem and did you fix it?

6

I don’i know if this car has a pellet type catalytic converter or a matrix type but I have seen the matrix type break up and fall back and clog the exhaust on hills. If this is the case, crawl under and tap the converter and you will hear the pieces of matrix rattle.

7

Long time reader and listener (I still remember the first CarTalk show I ever heard about 1988, a gal from Dallas was complaining about a too short dipstick and Click and Clack were very restrained).

My first post.

A very interesting problem, and I have a very WAG. Given that the thermostat is bad and engine temperature very low, I’m wondering if the long hill is causing the engine temperature to rise higher than usual, and making an electronic sensor or module fail because it is temperature sensitive. If so, replacing the thermostat might cause the engine to quit long before it ever reaches normal operating temperature. The bad part would seem to be one that isn’t setting a code, but I’m not at all familiar with this model.

I might add that IMHO running an engine with a stuck open thermostat long term is abusing the engine and terrible for gas mileage as well.

I’d also like to say that I’m always amazed at the depth and quality of the knowledge that you folks in the cartalk community bring to bear in solving problems for posters. Thanks for keeping me entertained!

Len

8

The CEL has been on for 6 years and you never thought to get the codes read? They could have done that at Autozone while you were there renting your pressure gauge.

9

The CEL may be simply caused by the car taking too long to warm up because the thermostat is stuck or missing. How is your gas mileage? A bad thermostat is one of the quickest payback repairs you can do.

So the car fails on a hill, but fuel pressure stays strong. Could there be a lot of electrical interference in that area? High tension wires? Radio towers or cell phone towers on top of the hill? If so, check the leads to the crank position sensor and the cam position sensor (if any) for shielding that is blistering off the lead.

10

I had an '85 Camry that would lose power and occasionally quit…but only on this one extended uphill at highway speeds.

Turned out, it was exhaust valves sticking…the car had a predisposition to this, and higher operating temps brought it out.

11

Hey guys, this thread was started on November 3rd.

The guy hasn’t posted back since November 4th.

I think we’re talking to a brick wall at this point.