optichris

I like the color. I'm trying to get the nerve up to paint my truck. Did you pull back the bed so you could paint the back of the cab? How much paint did you use? By the way, I'm also planning a turbo install on my 2.5L. I'd be interested to know some more about your experiences...

Matt, You may also want to check out the ignition coil. You can check the internet for more information, but generally this is how you check it: Take the coil out of the truck. Check for continuity on the primary and secondary sides of the coil. Do this by taking a ohm meter and putting one lead on the + pin and one lead on the - pin. You may have to unscrew the coil from the base (module). If the tester says infinite resistance, you have an open circuit in the coil and it is bad. If you have zero resistance, you are ok and can move to step two. Step two is a similar procedure, but this time have the one lead on the - pin and one lead on where the spark plug wire connects. Same test here, if zero resistance you are ok. This is a quick test that you can do that is free. It could be that your crank position sensor is fine, but your coil is bad. My advice: Check everything you can check before you throw any more parts at it...

is 89 a TBI or with a fuel rail? I just replaced the fuel pressure regulator on my TBI 86 and it was a piece of cake. You do have to pull the throttle body from the truck. Once you do that, no problem.

you need three things for the engine to run...spark, fuel, and air. Check these and you will probably find one of them missing. Usually, it isn't the air. You can check the spark by pulling a spark plug wire slightly off of the plug and see if you have spark. If you suspect fuel, you can put a couple of drops in the intake and see if it starts. There are a couple of ways to diagnose a no-start, these are just suggestions.

I don't have a 4.0L, but I know that a bad/foulded/disconnected crank position sensor will cause a no-spark condition. The ECU waits for the crank position sensor to tell it where the motor is, and then fires at the appropriate time...no crank position sensor, no fire. Just an idea.

I second the teamcherokee website. I got mine there too. I also purchased the window wipers for both sides which were all cracked and broken.

I searched high and low recently checking all the not-so-obvious things that would cause a rough, surging idle. When I got done checking all the sensors, all the wires, the grounds, the pumps, the injector, etc. I started checking the basics. Low and behold, I had low fuel pressure and needed to replace the fuel pressure regulator. Lesson learned: Check the basics first. Good luck.

Well, two different test drives and it seems to be fixed... I changed the spark plugs to OE Champions and adjusted the timing. Keep your fingers crossed! Thanks everyone for your help.

About the O2 Sensor - I am just out of college and also have just gotten married so I have little money and little time. I did some research and found out that O2 sensors modulate voltage between 0 volts and 1 volt. 1 volt being A/F rich, 0 volts being lean. What is different is whether or not the o2 has a heater. As far I as I know, the signals are the same, but the heater and plug are different. This truck is a bit of a patchwork - little of this and a little of that. I am trying to get it running the best I can with as little money as possible. Thanks for everyone's help. You guys have given me some great suggestions.

Here's the deal. After I did the 4WD conversion and rebuilt the motor, I put it all back together including the TBI. Immediately, I started having trouble with the truck surging and not idling. At the time, I took the half @$$ way out and installed a weber style carb along with a duraspark ignition module and different distributor. After some time with the truck running with the carb, I still wasn't happy. The truck ran fine, but the fuel economy wasn't good. Also the idle was a little rough. I knew that the only right thing to do (that was in my budget) was to put the truck back to the original TBI. So, here I am... UPDATE: I took the connectors apart for the ignition module and cleaned them all out. It looks like the module/connector is fine. I also took the advice to check the timing. It looks like I may have had the distributor off by one tooth. I won't call the problem fixed because I didn't have time to test drive it. Now, I'm watching the Bucs football game... GO BUCS!

here's an update.... Yesterday I followed the troubleshooting flow chart found in the FSM. Even though I was missing a few pages, I am fairly confident that the fuel injection system is working correctly. All of the sensors and circuits to the ECU check out fine with the exception of the MAP sensor. The manual says I should have less than 1.0V with 20" Hg. I have 1.2V. I will hold off replacing the MAP until I check everything else out - like the wires to the coil. I know that the connector to the coil is melted, so it is definitely suspect. I also know that I have non champion spark plugs. I will change those out too, just in case. One interesting thing that I found out through the troubleshooting is that the motor is running very cold...I think. Typically, it runs about 165-180 deg F. What is the proper operating temp for the 2.5? I will post back with another update today after some more checking. Thanks for your help.

My A/C doesn't blow very hard. As a check, I pulled the blower motor to make sure everything looked ok. While I was there, I reached inside and felt the evap core. It was covered with dirt, dust, hair, etc. I pulled off what I could and the blower started to work better. Now, I guess I have to bite the bullet and pull the housing and clean it out for real. The manual says there are about six nuts on the engine side of the firewall to take off. Once that is done, it should pull out. I can't believe it is that easy. Any tips? Thanks for your help.

Back when this truck was carburated, I replaced the original 3 wire sensor with a 1 wire sensor so I could see if the truck was running rich or lean. I never switched back to the 3 wire sensor. Instead, I wired the signal wire to the proper wire on the ECU harness. Is it worth spending the money for the 3 wire sensor?

Hi All. I have a 1986 Comanche with 2.5L 4x4 4spd manual trans. This truck started life as 2wd and I converted it over to a 4x4. I had the motor rebuilt and did most of the work myself. I am having trouble with the fuel injection system. The truck runs fine at idle (misses once in a while), but when driving and with throttle about 25 to 30 percent open, it looses power (does not quit) and acts like it is backfiring or coughing. If I go ahead and press the throttle further the engine returns to normal and speeds up. Here's what I have done: replaced crank sensor replaced TPS replaced fuel pressure regulator (fixed a prior surging problem) new fuel filter new fuel pump swapped coil/module with another used one I had swapped MAP sensor with another used one I had I have the factory fuel injection booklet. I checked the remaining sensors according to the manual and they check out fine. Not sure if it effects it or not, but I have removed the EGR valve and replaced it with a blank off plate. The charcoal cannister has been removed also. The PCV valve was removed and the hole plugged. I ran the vacuum hose to the rear valve cover filter breather from the throttle body. At this point, I don't know what else to try to fix the problem. The truck runs great otherwise. Any ideas? Thanks in advance. Your forums are a wealth of information. :bowdown: