Hi all,
After an extended break from jeeps (about 1.5 yrs) we recently picked up an 88 YJ heap-a-junk. 4.2l w/ a ba10/crap. The truck runs OK and for the $900 price tag wasn't too bad overall. I even drove it 60 miles back down everything from highways to back roads. However I noticed while driving and still now that the idle absolutely sucks. Every time I come to a stop or bring the RPMs down by even coasting, the jeep stutters and stalls. Furthermore, it is now difficult to even keep it running unless i keep a foot on the gas, keeping the RPMs up. When it dies and I push down on the throttle linkage, white smoke flows back up through the carb. When I can start it and keep it running for a bit, it is with the idle screw ALL THE WAY in, idling around 1200 RPM, however even then it will start to stumble, slow down, then pick back up etc etc. When it starts up there is a very slight white smoke coming from the tailpipe, and what I thought was oil was blowing out of the tailpipe. However it seems to mix well with water and washes off my hands easily so it may be dirty condensation. Here are the other diagnostics I have tried before coming to you guys:
- Took off and completely cleaned venturi cluster, as the description of this problem is basically EXACTLY what I am experiencing. No help
- Basic check for vacuum leaks. I can't keep it running very long so I couldn't do a thurough check, and I have the air cleaner off so all of those vacuum hoses are clamped shut. But there may be a vacuum leak that I haven't seen yet.
- The metering pins in the stepper motor are constantly all the way out, as in I can see the whole thing blocking the hole they are in (so all the way forward?) I tried unplugging the stepper motor but it didn't help the idle at all.
- The carb lets out white smoke if I open the throttle after the engine stalls
- The dizzy cap, rotor, and wires look to be relatively new. The coil does not.
I am planning on upgrading to a motorcraft carb in the next month or so, as soon as I get the money. At that time I'll try to eliminate as many vacuum lines as possible. I also have a spare carb the guy had laying around, and picked up a $10 rebuild kit at pep boys, figuring if nothing else at least I'll get the experience of rebuilding the carb. Just wondering what else I should try with it, and what solutions I should go about first. Thanks guys!