I have a 96 dakota with the 3.9L v6 (only 112,000 miles on truck) and it seems to run good. It has a misfire though, and no check engine light. It has been getting worse over the last few days. I changed, plugs, wires, distributor cap, and rotor. It seems to just be getting worse. The engine cuts out when I try and drive down the road. At idle, the misfire happens every so slightly at random intervals. Had a friend look into it, and he said it does not seem to be getting enough gas. Could this be my fuel pump? Was going to run some seafoam through gas to clean out the carb to see if it gets any better. Also got to pick up a fuel pressure gauge and test that before I go tearing stuff apart. A little concerned that this could be the timing chain, since I have read those like to go out on these trucks.

 

well take the plug that goes into the injector and undo it while the truck is running. it wont hurt anything. and if the truck changes pitch you know that cylinder is firing and move on but if it doesnt change at all then you may very well have a bad injector on your hands. which a junkyard injector with a o-ring kit should be the fix. also look into a fuel pressure regulator and definately look into some seafoam to run through it. and does it have any vaccum leaks. could also be a IAC or TPS just depends on wut happens when u start unpluging stuff one at a time really.

 

I'd check for CEL codes even though your not getting a CEL. Not all codes trigger the light. Good luck

 

Well, I hooked up my obd2 got a cylinder 4 misfire. Changed the plug wire and it still misfires. Checked the injector, and that is working fine. Now I am thinking it might be a bad spark plug.

 

How do you know the injector is working? Since you know which cylinder it is, remove that injector and swap it for another say number 1. Clear the codes and see if it comes back up on number 4 or number 1. If number now has the miss the injector is bad, if not and it is still number 4 then you have a wiring problem. Since your at it go ahead and toss in a new spark plug on number 4.

 

if you have already replaced plugs, wires, cap & rotor, I would check compression for cylinder #4 and the other cylinders while you're at it. The specs are minimum of 100 psi. You could have a bad head gasket or burnt valve. Also, double check you're checking the right cylinder.

 

Well I decided to start from scratch and remove the new distributor cap and rotor and disconnect all of my wires. I found something interesting underneath the cap. I have attached a picture of what I have found (hopefully it worked). Seems like cylinder #4 is not getting as much spark as the rest of the cylinders. I am going to exchange the cap and rotor tomorrow morning, thankfully I got a warrenty with them. Hopefully that will fix it. I got to pick up a new plug for that cylinder as well, even though they were just changed 2 months ago.

 

Well I got it fixed earlier this morning. Turns out my new distributor cap and rotor were bad. I exchanged them for another set of new ones and it fired right up with no issues. Lesson learned, don't always trust the parts u buy.

 

So true! One of the three new sensors I bought is bad, I just have to figure out which one lol. Glad you got it fixed man