[Captain Kirk]

Several of you fellas suggested that my problem might be a clogged catalytic converter. Well, I did a test and that's not it.

I cut the Y-pipe before the converter and let it hang free. Upon cold start-up, the motor ran fine (like always). Without a muffler it sounded GREAT! After about a minute I thought maybe this was it -- but then at about 2 minutes of running, like before, it just flipped into coughing and choking with absolutely no throttle response. When I shut it off and restarted, it ran rough again right away.

Again, no SES light at any time. On-frame fuel filter has also been replaced.

I have no idea how the TBI electronics works, but if it were a carb system its like the high speed cold idle solves the problem but when that "kicks down", then the crash.

Any further ideas? Again, I'm stuck at home in the mountains without enough power to limp anywhere and $100 tow from the shop.

Thanks very much. Bob

 

[Captain Kirk]

Yes, I see a spray coming from each of the two injectors in the throttle body. Actually looks like plenty of fuel hitting the throttle plates.

 

[Captain Kirk]

Check the EGR, and the PCV valves.. they can also cause this.. In my 88 that i had it did something sounding a lot like what your problem is.. and it turned out that both were bad..
Or else i know that my 1991 had the connector come off of the TPS sensor and it also did this. But is the check engine light on?

Murdog: Thanks for the thoughts. I'll check the PVC. No, the check engine light is working but is not coming on while truck's running.

What's the EGR valave and where do I find it? Seems like its a $150 part -- is there any way to test it or rehab the one I have?

Thanks. Bob