88 4.0 Misfiring?

[cromanyak]

I have an 88 Comanche with the 4.0 and its not firing on one cylinder. At first I thought it wasn't getting spark so I did new plugs wires and dist. cap but now it is getting spark but still no firing. When I pull the plug it smells faintly of gas but shouldn't it be wet if it was getting fuel. I'm thinking injector? What else could it be?

[Pete M]

It's possible that the injector is clogged or that it's receiving a weak signal (or no signal at all) :dunno:

[cromanyak]

Do you know of any way to test for either of those? :mad:

[Pete M]

I'm sure there are official ways of doing that, but I don't know what they are. I'd probably swap it with its neighbor and see if the missing moves. :dunno:

[cromanyak]

I swapped around injectors. Still no fuel on the same cylinder. So I'm guessing its not getting a signal. I tried swapping the injector plugs also but no change. Any advice on what to do from here?

[mvusse]

Check the wiring going to that injector.

[Oizarod115]

try a 3 or 5watt tag bulb from any parts store.

fold the little metal tabs down off the base of the bulb, plug them into the injector harness from that cylinder and start the truck, you should see the bulb flicker on-off

 

if the bulb doesnt light (it may be very faint/hard to see in bright daylight) check and make sure it has good connection at the plug and that the bulb works when given 12v... if you determine the injector harness is not giving signal then check to see whats going on with wiring

[dfreeman616]

if you have a voltage meter/multi meter/ test light, one terminal on the injector harness should have constant voltage key-on, and the other should pulse the ground signal as the engine is running. if that all checks out, next thing to do is check compression. if you don't have a gauge, you can rent them from somewhere like autozone, o'riley's or advance auto for a deposit fee.