Engine Stalls After Warming Up...I'm Stumped

[GM3300GUY]

Greetings, all! I am a newbie to this site, but an experienced DIY mechanic, but my current problem has me and my mechanic both stumped.

My car is a 1992 Buick Century 3.3L with 190,000 miles on the clock. Unfortunately, the only Buick forum I found is essentially useless and there aren't too many Century enthusiasts. Anyway, since the Century has the same motor as some Grand Ams from '92, maybe you guys can help...

My problems started last spring with high idle, bucking, stalling, etc. It sat on my lawn from April until a few weeks ago when it started snowing (it's my winter car). Long story short, after replacing / testing the O2 sensor, IACV, plugs & wires / alternator (system said it was charging at 25 volts), and ignition module (1992 specific :wtf:) with no luck, I replaced the ECM (computer box behind glovebox). Success! It ran perfect, for a week.

Now onto my current problem: The car runs fine until after it warms up. After about 20 minutes / 5 miles it stalls. It will reluctantly restart a few times, but keeps wanting to stall. I can continue to limp it onward for a mile or two after this happens. Then the motor will lose all power and gradually slow down (with my foot into the gas to keep it running) until it stalls.

Once it cools down (leave it sit for an hour or so) it will start right up and be fine until it warms up again and the whole thing starts over again...

My mechanic has had it on his top-of-the-line scanner, checked the injectors, checked for spark, fuel pressure, etc. with no luck.

Some electronic component is failing and does so when it gets warm. Now I ask you: got any ideas? Help!!!:help2:

Other ideas being kicked around: crank sensor, ignition module (the one I replaced is used), umm?

[GM3300GUY]

Wow, you guys really know your stuff! Thanks for the replies, it really helped NOT...

Well, no thanks to any of you it's fixed...And just for not even suggesting anything, I'm not gonna say what it was!

[GM3300GUY]

Here's what useful advice from another forum looks like:

Hook a fuel pressure gauge up in-line and tape it to the windshield. Observe readings when power loss issue occurs and report back. The gradual loss of power is consistent with an overheating fuel pump. If this is the case, PSI will drop, and amperage draw by the pump should spike.

Have your "mechanic" scope the crank sensor with his MODIS or whatever else he's using and compare the waveform to known good GM 3.3 8/24x crank waveforms. However, bad crank sensor doesn't usually result in a gradual loss of power, more like a sudden stall and no start condition.

If you got the ECU used, swap it out again -- it may have a failing solder joint inside that is causing an open circuit when it heats up.

If it's really been sitting since April, replacement of the fuel filter as well as a tank drain and refill would be good ideas.

FYI: it ended up being the crank sensor...you're welcome.

[Brad97GS]

Look bud, the fact is that not many people here own this engine, so this section doesn't get much traffic. Had this been posted in the Problems/Solutions section, I'll bet you would have gotten some help. I don't fault you for posting it in this section, as I'm sure you don't know that this is a slower section, but it sure was disappointing to see your reaction after only three days of no responses.