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  1. SOLVED! Thanks for your help. It ended up being a bad MAP sensor. I checked all of the grounds and everything as you said, and everything checked out okay. Installed a new ISA and got it working right with no change. We weren't completely satisfied with the replacement fuel pump we put in, so we pulled it and come to find out it was the one for the 6 cyl engine, and apparently there is decent difference in output. I don't think this would have made much difference, but while we were doing that, I just thought to myself, since I've already thrown so many parts at it, the only thing I haven't replaced pretty much was the MAP, so I got one, installed it, and she fired right up and idled great.
  2. Thanks Moses, I am going to get a new ISA ordered, and go back over the grounds, and let you know what I come up with, and we can go from there. Thanks again for the help. All of my searches and research on this topic seem to have led back to you being the leading authority on these, so I figure if anyone can help me, it'd be you. This forum seems to have the most info on these by far. I have been looking for a complete running 2.5 truck locally that I can at least look over to make sure I've got all my connectors and everything right, and nothing is missing, but no luck on that yet.
  3. Hi all, I am new to this forum, and to Jeeps in general. I recently got a 1990 Comanche 2wd, with the 2.5 TBI engine, and over the past few months have been trying to get it going. It was parked for about 10 years due to a bad transmission, and possibly the issue that I have now encountered. I am going to try to be as thorough as possible, but I am stuck and need some outside eyes. My dad is a professional mechanic with his own shop, so I have tools etc. at my disposal, but this thing has both of us stumped. Issue: I replaced the fuel pump and tank, flushed the system, along with did some wiring repairs that rats had eaten. I believe I have everything on the fuel system and electrical system correct. I can turn the key on, the pump will prime, and the engine will start, but immediately dies. I can start it, and begin "pumping" the accelerator, and it will remain running as long as I do so, but if I stop, or try to hold the accelerator in one position, it will die. It appears to have sufficient fuel pressure while running, it seems as though the injector pulse is going away before it is able to idle. I can manually ground one side of the injector, and force it to fire, and keep the engine running this way, by pulsing the injector myself, but it will not do this on it's own. I know the ISA is bad, and it is not working, but it doesn't seem like it would cause this issue? Parts I have replaced with new ones, no change in symptoms: Computer, fuel pump, fuel tank, CPS (Crank sensor), Parts I have replaced with other used parts, no change in symptoms: TPS, Ignition module, Fuel Injector, Complete throttle body, fuel pressure regulator. Any help would be greatly appreciated. Thanks!
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