Hey yall, i belong in the 80-86 section but a buddy in NC has this truck. Driving home it shut off on him, no restart. He tried a icm but that wasnt it. He tells me when grounding a plug it gets no spark but he gets a single shock felt at the very end of being cranked. I was thinking maybe pickup coil/stator but he cant throw money around. I found something called a ignition suppression resistor in a 90 wiring diagram but nothing on autozone.com for a replacement or part number. Any ideas here?

 

First make sure it has power to the coil, through one of the small wires that hooks onto the coil, with the ignition switch turned ON. If that is good I would try to get the coil tested. Then I would replace the distributor with a NEW aftermarket distributor from a place like Oreilly Auto Parts. We have determined most rebuilt distributors are junk.

 

Pull the cap and make sure the dizzy is actually spinning. The 300 is known for shearing the roll pin that holds the gear to the distributor.

 

Probably the ignition module. You can remove it and have it tested at most parts stores.

 

Hey thanks yall. Module was tested good 5 times at advance, 3 times at oreileys. Same part number for his 90 and my 86, mine passed 5 times testing but was still bad, weird but ok, it fixed mine last year .

Dizzy is rotating. He is getting power on red/lt green. Connections are tight and cleaned. The tan/yellow wire is what has the resistor. Its between the coil/module connection and the ecm. He is in NC and im 90 miles away in VA. I cant get hands on, trying to work him through the steps of finding and fixing. I just aint up to date on the efi 300s operating system.

I do appreciate yalls info, ideas, and help.

 

The ignition suppressor resistor is only there to act as a current limiting device to feed the IDM signal to the computer (PCM). I seriously doubt that is causing your no spark issue. The IDM signal tells the computer the coil is firing, that's it.

Since you have power to the coil I suggest you test the coil, it can be measured with a DVM for resistance on the primary and secondary circuits. Not sure of the values, too lazy to look it up.

You can also remove the connector to the computer (PCM) then try cranking the engine again. If you get spark, then you have a bad computer.

If there is still no spark you have a stator issue (PIP) or a wire problem.

 

Hey thanks man. He tried a new coil a couple days ago he said.

I found online you could test a orange and purple wire for 400-700 ohms of resistance. And 0 for orange or purple and black. Only he says he cant locate these wires at the dizzy.

 

HOW TO TEST AN IGNITION COIL
WARNING: Never pull off a plug wire or the coil's high voltage output wire to test for a spark. Besides risking a severe shock, an open plug wire or coil wire will increase the voltage demands on the coil to the point where it may damage the coil. The only safe way to test for spark is to use a spark plug tester tool.
If a coil problem is suspected, measure the coil's primary and secondary resistance with an ohmmeter. If either is out of specifications, the coil needs to be replaced.
A coil can be easily bench tested with a digital 10 megaohm impedance ohmmeter. Refer to the vehicle manufacturers service information for the coil test specifications because the values can vary depending on the application.




To test the ignition coil connect the ohmmeter's two test leads to the coils primary terminals (+ and -). Most coils should read between 0.4 and 2 ohms. Ford = 0.3 to 1.0 Ohms. Zero resistance would indicate a shorted coil while a high resistance reading would indicate an open coil.
Secondary resistance is measured between the positive (+) terminal and high voltage output terminal. Newer coils with segmented core construction typically read 6,000 to 8,000 ohms, while others can may read as high as 15,000 ohms. Ford = 6000 to 15,000 ohms.

On coils that are not a can style, the primary terminals may be located in a connector or even under the coil. Refer to the vehicle manufacturer's service information for the terminal locations and ignition coil test procedures.

Cut from this URL: http://www.aa1car.com/library/ignition_coils.htm