a huge problem with my YJ brings me to this forum, so I'm a new member.
I own a 1989 Wrangler YJ 2.5L 5-speed. It's a '94 block, with the '89 accessories/head/etc.
I drove my Jeep to work one day a couple weeks ago. No issues. Went to leave to grab some lunch at a local restaurant and it started idling not well in about 20 seconds after starting it up. Tried to just drive it anyways, and the power would completely cut out as if I were idling, even though I had it almost floored. The RPMs would go from ~2500 down to ~1000 where it would stay until I got off the gas, when it would die. I started it up a couple times, but it would repeat the process. Luckily I was able to do a U-turn and coast into my work's parking lot.
tried to drive it home afterwards and it would do the same thing, over and over. It seemed to run well off of the gas I used to start the Jeep with, bringing itself up to ~3000rpms, and I would be able to quickly get it in gear and drive it. but after that gas was used up, it wouldnt want to run anymore and would die. Luckily there were no cars on the road and I was able to make it about a mile to my grandfather's house, where the Jeep sits now, unable to even idle well.
My Jeep will start fine after it's been sitting awhile, go up to 2k rpms as usual, but will quickly fall to around 600rpms and try to die. if I give it gas, it doesnt like it and ends up flooding itself out rather than gain rpms.
It won't start again after that unless the gas pedal is to the floor, because it's flooding itself out. While it's doing this, it produces white smoke and condensation that leads to black all on the cement under the tailpipe.
Now for what I've tried to do about it. I've done alot, so I'll try to be as thorough but organized as possible.
I dropped the gas tank, dried it COMPLETELY out, because I had water in the tank before this. New spark plugs, a full tank of new gas, a new fuel filter, and jumping the fuel pump relay to flush the throttle body. No difference.
I got a new injector a few days before this started, because the old one was seemingly clogged. When the throttle body bonnet is pulled off, I can hear a sort of hissing sound coming from the injector. I tried getting the old one cleaned out and trying it, but it's the same as the new one, so the problem probably doesnt lie there. However, along with the hissing, the spraying seems to mess up when it happens. However, it's flooding so I'm not sure if that is a cause or a symptom.
The fuel pressure was good, the return line I blew into with my lips and heard it bubble in the tank, so it's not blocked.
Tested for vacuum...5in HG if I'm lucky. The other day before I put the new injector in, it was bouncing from I think 10in HG back down to 0in HG rapidly. Now it just goes beween ~0-3.
Pulled the Throttle Body off, the gasket was good and it's clean. The fuel pressure regulator is seemingly fine. the IAC is acting normally and isnt very old. The CTS is within it's range at ~70F (~3400Ohms). The MAT sensor is a little off, but I have the '91-'95 sensor, so I have to look at the ranges on that. SHouldnt affect my Jeep that massivley anyways if it's only a little off.
The TPS is good and within range. The WOT sensor is working. New MAP sensor as well. Checked all my vacuum lines and they are all good and routed correctly. I plugged the brake booster, no change. Plugged the EGR/Charcoal cannister/Purge solenoid vac line @ the purge solenoid, no change.
I was worried about the head, and did a compression test, passed perfectly. All of them within 120-130. the timing test also passed great. I pulled the ECU out and there are no indications of heat or corrosion.
I'm not sure what else to do. I checked around the intake manifold for a leak in the gasket, but the gasket isnt very old and I didnt see anything. However, I can still do the WD-40 test, spraying around where it bolts up.
I havent checked the O2 sensor, but my manual says it doesnt take O2 into consideration until the vehicle is warmed up. I may have a clogged cat because the cat is old, but would that cause effects this major? Another thing is my power steering switch broke off the line and shorted on the exhaust manifold awhile ago that blew the computer, so I got a new one.
I cut the switch off, taped up the lines, and it ran great for a few days after that until this started, so I dont think it matters. But I figured I'd include it.
I know this was a long post, and I'm sorry, but I'm incredibly frustrated with it, after having all sorts of issues for the past two months. This one I just can't figure out. Any help would be greatly appreciated.