madmusic5 Posted December 18, 2018 Share Posted December 18, 2018 So far I have replaced the spark plugs and wires, distributor cap and rotor, ignition coil and module, crankshaft position sensor, and fuel filter. It turns over, but quickly shuts off. When I turn key to first position I hear a click, which I believe is the fuel pump engaging. Any ideas on where to go next? Also, what is the part next to air intake in the attached pic? It is disconnected and once of the wires appears to be cut. It looks like it feeds into the air intake and probably the ignition coil. This was disconnected while the truck was running. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 18, 2018 Share Posted December 18, 2018 So, it turns over and starts? Then dies quickly? If so, it might be a bad fuel pump ballast resistor. You can bypass it for testing purposes and see what happens. Link to comment Share on other sites More sharing options...
Eagle Posted December 19, 2018 Share Posted December 19, 2018 19 hours ago, madmusic5 said: So far I have replaced the spark plugs and wires, distributor cap and rotor, ignition coil and module, crankshaft position sensor, and fuel filter. It turns over, but quickly shuts off. When I turn key to first position I hear a click, which I believe is the fuel pump engaging. Any ideas on where to go next? The click could be the fuel pump relay, but there's a long circuit between the relay and the pump. When you first turn the key on, you should hear the fuel pump running. If not, you need to check the entire circuit. Cruiser's suggestion on the ballast resistor is a good starting point. Have you checked the fuel pressure in the injector rail? Link to comment Share on other sites More sharing options...
madmusic5 Posted December 19, 2018 Author Share Posted December 19, 2018 Well the truck also has many wires that are disconnected. I should mention I'm a newb to any auto work. The ballast resistor is not even in the truck and I could only find one of the wires that connects to it. Does continuous driving without the ballast resistor cause other parts to fail? I'm thinking I may just need to take it in. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 19, 2018 Share Posted December 19, 2018 Driving without a ballast resistor causes no issues, Link to comment Share on other sites More sharing options...
Eagle Posted December 19, 2018 Share Posted December 19, 2018 2 hours ago, madmusic5 said: Well the truck also has many wires that are disconnected. I should mention I'm a newb to any auto work. The ballast resistor is not even in the truck and I could only find one of the wires that connects to it. Does continuous driving without the ballast resistor cause other parts to fail? I'm thinking I may just need to take it in. Did I understand that the truck was running before you did the tune-up? What year is the truck? The ballast resistor wasn't used in 1987 -- it was introduced in the 1988 model run. Also, please clarify the opening post. "Turning over" means the starter is turning the engine, but the engine is not running and won't start. "Firing" means it coughs and sputters while cranking (turning over), but the engine won't actually start. If the engine actually starts and runs for a few seconds, that's yet another condition. We need to know exactly what it's doing before we can be of much help. Link to comment Share on other sites More sharing options...
Minuit Posted December 19, 2018 Share Posted December 19, 2018 Yeah - before we can help we need to know what the symptom actually is. Don't resign yourself to taking it in just yet. If you figure it out this will be a very valuable lesson in diagnostics moving forward, and if you're gonna own an old vehicle, that skill is gonna come in handy. It'll feel damn good when you get it running too. Use the terms that Eagle used for "turning over" and "firing" in the post above this one. If it does run after attempting to start, how does it run? Does it sound really bad and shake a bunch, or does it run like a normal engine for just a few seconds and then die? If the answer to the last question is yes, for about how long does it run? Finally, and most importantly, - we need to know what you have. There were a very large variety of engine and fuel system combinations used in our trucks over the years, and every combination might as well be completely different vehicles for the purposes of your problem. Create a signature (click this text) with year, engine, and transmission at the very least. Link to comment Share on other sites More sharing options...
madmusic5 Posted December 19, 2018 Author Share Posted December 19, 2018 I tried updating my signature, hope it worked okay. If not, I have an 88 Comanche, 2wd, 2.5L 4-cylinder, 4-speed manual transmission. Thanks for clarifying the terms. The truck does start and quickly dies afterwards, almost immediately. As to how it runs I will get back to you tomorrow with more detail. It was running decent after all the repairs I mentioned in the original post. When it was regularly running it still did not start up well. I would have to give it some gas sometimes, mostly when the engine was cold. to get it idling okay. It would also sputter occasionally when I was driving, like it wasn't getting enough fuel. It seemed to happen randomly and not due to anything in particular. Link to comment Share on other sites More sharing options...
madmusic5 Posted December 27, 2018 Author Share Posted December 27, 2018 I got tied up the last few days with the holidays and all. I thought some videos might be better than describing the start-up, they are attached. Hope this helps! VID_20181226_173415.mp4 VID_20181226_173440.mp4 Link to comment Share on other sites More sharing options...
Eagle Posted December 27, 2018 Share Posted December 27, 2018 So it starts, but doesn't stay running after the key is released to the RUN position. Does the '88 2.5L have a fuel pump ballast resistor? If so, try jumping the terminals. Link to comment Share on other sites More sharing options...
madmusic5 Posted December 27, 2018 Author Share Posted December 27, 2018 It only starts when I give it gas, and then immediately dies, even if I rev the engine. The ballast resistor is non-existent. I see where it should be, but it was not there when I bought the truck. I believe I located one of the cords, but can't find the other one. There are at least 6 wires that are disconnected. But it was driving decently, even with all the disconnected wires. Link to comment Share on other sites More sharing options...
Eagle Posted December 27, 2018 Share Posted December 27, 2018 If you feel daring and you have a helper, you can dribble some gas into the throttle body, start it, then keep dribbling gas in and see if it will stay running. That's a simple way of confirming that the problem is a fuel delivery problem. Just be sure you have a good, working fire extinguisher handy. If the truck has evr backfired through the throttle body, DO NOT try the gas dribble method of trying to run it. A backfire would not be a good thing ... Link to comment Share on other sites More sharing options...
Jeep Driver Posted December 27, 2018 Share Posted December 27, 2018 4 hours ago, madmusic5 said: It only starts when I give it gas, and then immediately dies, even if I rev the engine. The ballast resistor is non-existent. I see where it should be, but it was not there when I bought the truck. I believe I located one of the cords, but can't find the other one. There are at least 6 wires that are disconnected. But it was driving decently, even with all the disconnected wires. The six wires you are referring to likely operates the idle control motor, it will run without it, not necessary. You can take the intake hat off and watch the injector spray fuel. It's either related to the fuel pump or MAP, one or the other. Clean the vacuum port to the MAP, replace line with new vacuum hose, replace MAP. There is no ballast resistor on the 88 2.5. When you turn the key to ign the ECU runs the pump for 3-4 seconds (prime function) then turns the pump off. Pump does not run again until starter is engaged. If the ECU does not receive information from the sensors, MAP would be one, it will shut down the pump again. This is what is sounds like to me, MAP. Link to comment Share on other sites More sharing options...
cruiser54 Posted December 27, 2018 Share Posted December 27, 2018 Good suggestions here. Another one. Make sure the ground cable at the firewall has the paint removed from underneath it. Link to comment Share on other sites More sharing options...
Eagle Posted December 27, 2018 Share Posted December 27, 2018 http://www.bteventures.com//mj1988electricalmanual.pdf Scroll down to pages 15 and 16 (of the PDF) Link to comment Share on other sites More sharing options...
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