96 Jimmy acceleration and stalling

[flivesay]

96 Jimmy with W engine 168 k miles. No codes (check engine light) are being set. Following warm up, when depressing the throttle, the engine appears to die (under load--does not do this in neutral). When releasing the throttle, the engine comes back alive. I can ease the throttle to a certain point, but past that I only get induction sound and the engine does not pull. When I stop at a redlight the engine may continue to run, or the rpms drop to 500 and then as soon as I start to go, the engine stalls and it takes several tries to restart.

I have cleaned the MAF, checked the EGR, replaced the PCV, changed the fuel filter, o2 sensors are 6 months old, checked lines for vacumn leaks. Did I mention no codes are being set?

Other probably unrelated info is: catalytic converter rattling, ABS light on all the time, air bag light on all the time.

Any ideas or experience?

flivesay

[obadran]

I almost have a similar problem with my 96 yukon with 100500 miles on. I would have intermittent extra long crank times to get the truck started and also a lack of power on moderate to full throttle acceleration. I eventually, under a full throttle accelaration got the check engine light to come on. The codes pointed to my o2 sensors and that the o2 sensor were detecting a lean condition.
I took it to the dealer and explained everything along with the fact that I have to replace my fuel filter every year to avoid stalling due to a plugged filter.....Summer of '03, I was stranded on the PA turnpike 5 hours from home due to a clogged fuel filter. Long story short, they found 'stuff' floating in my gas tank....I got a full fuel system cleaning/flushing from the injectors all the way back to the gas tank. For the most part the problem is solved, but I still think something else is wrong and it's probably something electronic so I guess I'll have to wait until it dies completly.

In the fuel tank, the fuel pump has a filter screen and if it is clogged you will get reduced fuel flow. With 168K miles on your truck, I wouldn't be surprised to find 'stuff' floating in the tank. 168k is a lot of fill up at the station.

Hope this helps

[flivesay]

After reading everything I could find on this forum and gleening what info I could from the cheapo manual I have, I decided to replace the fuel pump. That was the problem. Apparently it was low flow---enough pressure to start and run, but not enough for mid throttle and above (requires 60 psi to start).

One note from the replacement procedure---disconnect the line from the EVAP valve on the forward end of the tank prior to dropping the tank. I didn't realize it was there and so broke the nipple from the valve. 12$ from the dealer. Complete pump/gage assembly from NAPA, 126$. Time to r & r--approx 3 hours.

fl

[mivud]

- not a solution, but what i have experienced

I have a 91, 280Km / 4.3L ... and I too have noticed the "service engine" light come on frequently. I noticed it coming on when you drive the vehicle rough ( i.e. hard acceleration/quick braking ), the light flashed on, and then feel the engine about to stale, where i then ease off the throttle, and re-gain the power ... quite frightening if you ask me. So far i have done the following as per "so called" mechanics

- full engine tune up, with d/c & rotor
- fuel filter
- changed mapping sensor

next step maybe the o2 sensor && god help me "timing belt" b/c the mechanic hears the engine to be on the low power end ... $$$$$$

keep you all posted