Eye Behold Posted January 10, 2018 Share Posted January 10, 2018 My 87' Comanche has been giving me issues after every drive. Seems like one drive = 2 repairs lately. I have done plugs, plug wires, fuel filter, injectors, distributor cap and rotor, fuel pump is not very old, was replaced with new fuel tank (All of this work done over time not at once). cooling system is all new, pulleys, belts and hoses are new, alternator, and various other things. I baby this truck and it has been absolutely reliable until the last month. I replaced plugs, plug wires, and took it to a shop to do the distributor cap and timing. Got it back and it drove great for one day. Then it wouldn't start for almost a month. I tried it two days ago and its alive again and runs fantastic for the day. I did multiple trips in it to see if it would crap out on me again and it didn't that day. Today, won't turn over. Battery seemed a little low so I put the trickle charger on and got it back up, still will not start. Just cranks. Before (after getting it from the shop) it would turn over, sputter, almost die if you revved it, and eventually die after 10 seconds or so. Now it does not start at all. Any ideas? I am leaning toward a bad fuel pump, and I can tow it to a shop to have it worked on, but if I can figure this out and do the work myself, it would be great. One thing I should note, it is 25 degrees cooler today than the day it ran fine if that helps. here's the other funny thing about this truck, I pass an airport on my way to work. I drive 12 miles and then I pass the airport. Every single time I pass that airport it will just about shut off. It sputters, lurches, and then goes back to normal once I am past the airport and at work. I have no idea why it does this, but it does it every time I pass the airport. Anyone have a clue why it would do this? Link to comment Share on other sites More sharing options...
87MJTIM Posted January 10, 2018 Share Posted January 10, 2018 Can you give us some more info about your truck? Yr, engine, trans. These are always the first place to start. Also, you listed what you've done. How about a description of the problems. I don't think driving past the airport really could effect the truck. Link to comment Share on other sites More sharing options...
Eye Behold Posted January 10, 2018 Author Share Posted January 10, 2018 Yes, 1987 Jeep Comanche 4.0 Automatic 4x4 Right now it will crank but not turn over. I am trying to attach a video from my phone but the attachment restrictions are too low to upload it so, I'll try to post it somewhere and copy the URL. As for the airport, I was kinda joking but I record video with my phone showing that it does it when i pass the runway, coworkers find it strange but funny Link to comment Share on other sites More sharing options...
87MJTIM Posted January 10, 2018 Share Posted January 10, 2018 Check out Cruisers Renix Tips before you throw more parts at it. www.Cruiser54.com Link to comment Share on other sites More sharing options...
Eagle Posted January 11, 2018 Share Posted January 11, 2018 2 hours ago, Eye Behold said: Today, won't turn over. Battery seemed a little low so I put the trickle charger on and got it back up, still will not start. Just cranks. Before (after getting it from the shop) it would turn over, sputter, almost die if you revved it, and eventually die after 10 seconds or so. Now it does not start at all. Cranking is "turning over." Please be more clear in trying to explain the problem. Does it crank but not fire, or not crank at all? How old is the CPS? Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 11, 2018 Share Posted January 11, 2018 I would check cps.^^^^ dirty, loose bolted or bad cps could be the issue. Link to comment Share on other sites More sharing options...
Eye Behold Posted January 11, 2018 Author Share Posted January 11, 2018 3 hours ago, Eagle said: Cranking is "turning over." Please be more clear in trying to explain the problem. Does it crank but not fire, or not crank at all? How old is the CPS? 31 minutes ago, Noriyori_Kudo said: I would check cps.^^^^ dirty, loose bolted or bad cps could be the issue. CPS is about one year old. This very well could be the problem. Now that I think back, I did change the original last year after it gave me similar issues. I'll give that a look tomorrow and see if thats my problem. Knew I had to be over thinking it and you guys would point me in the right direction. Link to comment Share on other sites More sharing options...
mjeff87 Posted January 11, 2018 Share Posted January 11, 2018 My vote would be O2 or MAP sensor. You can unplug the O2 and see if it makes any difference. About the airport thing.......I came across this very interesting problem-solving methodology awhile back: http://www.kepner-tregoe.com/blog/help-my-car-is-allergic-to-vanilla-ice-cream-a-study-in-problem-solving-part-i/ It's a pretty interesting read, and solution. Read the first part and try to figure it out. If you can't, click and read part 2 for the solution. We need to think "out of the box" sometimes..... Jeff Link to comment Share on other sites More sharing options...
Marine1Texas Posted January 11, 2018 Share Posted January 11, 2018 02 would only cause it to run rich/ lean or Map Sensor would not would not interfere with firing on start. If you turn over (crank) and nothing in a Renix I would go 1.) CPS 2.) spark plugs/wires/cap .... If you have spark most likely you can move on 3.) fuel pressure 31/39 .... fuel pump working even with 20 psi it should fire 4.) coil I have has 2 cps die in 30 years on my 87. the key is good product and keeping it clean. about 7 years ago we had the coil go out. At that time it was a Saturday morning and nothing open till the new year, soo we put in a old 4.2L HEI Dizzy with built in coil that does not require computer or cps to fire. We timed it and it been sitting in since. The nice thing about the HEI it fires on first next cylinder, no waiting for full rotation. We never switched it back because not one failure making us do so. Link to comment Share on other sites More sharing options...
Ωhm Posted January 11, 2018 Share Posted January 11, 2018 Airport issue: I'll assume your running with a working Knock Sensor (KS). The circuit between the KS and the ECU is a shielded circuit. This circuit if not grounded properly is subject to induced ElectroMotive Forces (EMF), hence the reason for the shield. The KS is designed to retard any advance timing during a engine knock condition. Could what your seeing during your airport span be that the timing is just being retarded way more than normal due to airport EMF's? Link to comment Share on other sites More sharing options...
mjeff87 Posted January 12, 2018 Share Posted January 12, 2018 ^^^awesome deductive reasonong Link to comment Share on other sites More sharing options...
cruiser54 Posted January 12, 2018 Share Posted January 12, 2018 Do Tips 1 through 5 at www.cruiser54.com before anything else. Link to comment Share on other sites More sharing options...
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