I got a 1992, 4.9 engine. I run the diagnostic tests and am getting power to the coil but no spark out of the coil. I changed out the coil and get the same results. This really has me scratching my head...Distributor Cap and button are less than a year old. Tried a new pick up coil and Module...still no luck. If anyone has a clue "PLEASE" let me know.

 

Starter relay?

 

Bad plug that snaps onto the coil. You should have power on both small wires with the key on. I bet you only have power on one of them.

 

That is what is confusing. I have power in both wires.

 

Hmm, I have a suggestion. If there is power to the coil it should spark. So, Does anyone think his ignition switch could be bad causing no power to the coil while in the key is in "Start" position??? A good way to try this is turn the key to "On" and jump the starter relay to see if it starts. If it does start, It's something with the ignition switch or something. Just a thought because if you have power, your coil SHOULD spark. That's what confused me..

Good luck!

*Oh one more thing. If it's a manual trans, make sure it's in neutral and someone is pushing the clutch in. Jumping the Starter Relay bypasses ALL safety switches*

 

Do you have a tachometer in the truck? If you do, does it show any RPM reading when cranking the truck? If you do not have a tach attach a meter or test light to the coil. Have someone crank the engine, does the test light blink or if using a meter does it display any voltage? Should be in the 3 to 6 volt range.

If any of those fail it could be a wiring problem. You mentioned before you replaced the PIP and TFI. So unless you got another bad one straight out of the box it is looking like a connector or wiring problem.

Another test to try is momentarily ground the negative side of the coil, see if you have spark. If you do then the problem is on the negative (trigger) side. If not perhaps that supply voltage you measured is really stray/phantom voltage from an open circuit.

 

Does the tan wire with a yellow stripe at the coil flash when it is cranked?

If it does not then unplug the Computer and see if you have spark and the tan wire with a yellow stripe at the coil flashes then.

 

I know that you changed out the PIP, but it could still be the problem...pull any stored codes yet?

 

I appreciate all the help and suggestions. I will try all of them until I get a resolution. I have a mechanic friend that is bringing his computer over and see if we can pull a code.

I'll keep you all informed on what I find...and once again "THANKS".

 

FOUND IT!!! and I never would have guessed. A wire under the fuse box was worn and shorted out. It in turn fried the computer.

Thanks again for all the suggestions and help.

 

Can you tell us more about this wire?
What color was it?
Did it have a color stripe on it?