burning up pickup coils

Reply Subscribe

Thread Tools

Search this Thread

Apr 21, 2003 | 05:14 PM

balingwire

Thread Starter

Mountain Pass

Joined: Apr 2003

Posts: 248

Likes: 2

burning up pickup coils

I have a '78 F-150 4x4 that came with a 300 six and 4-speed. However, the 300 was replaced with a '77 351M. The truck ran perfectly for about four years, then started burning up pickup coils in the distributor. This has happened five times. Twice running on the interstate at about 3000 rpm, once on the highway at 2200 rpm, and twice on back roads at 1500-2000 rpm. The engine would be running great, then the tach needle would bobble, the truck would buck violently a couple of times, and then it would die. No fire. Once the pickup coil was replaced it might run 3 months or two weeks before happening again. During the five times that this has happened, we have replaced the everything we could think of, lastly replacing the ignition switch assemby, which (knock on wood) appears to have corrected the problem for some reason. However, I am still gun-shy when it comes to jumping in the truck for a long trip. Has anyone had this trouble and, if so, what did you do to fix it?

Apr 21, 2003 | 07:00 PM

gregdatech

Senior User

Joined: Mar 2002

Posts: 177

Likes: 0

From: Sapulpa

burning up pickup coils

Make sure the wiring is in good condition. All it takes is one tiny spot rubbed thru and it will give all appearances of a bad pickup. Have you checked for play in the distributor shaft?

Apr 21, 2003 | 07:36 PM

balingwire

Thread Starter

Mountain Pass

Joined: Apr 2003

Posts: 248

Likes: 2

burning up pickup coils

We replaced the distributor. It ran great for a while, up until it died again. We called ourselves inspecting the wiring, but it's worth a second look. Thanks.

Apr 21, 2003 | 07:37 PM

thelonerangerxlt

Posting Guru

Joined: Aug 2000

Posts: 1,984

Likes: 2

burning up pickup coils

I doubt that all 5 of the pickup coils were really bad, bailingwire.....

Check the black wire going from the ignition module to the distributor. This is the ground wire. You might try removing it and cleaning the connection. Check the connector plugs too, and the entire black wire circuit for continuity.

Apr 22, 2003 | 03:07 AM

Torque1st

Posting Legend

Joined: Sep 2001

Posts: 30,255

Likes: 37

burning up pickup coils

Check the ground wire connection to the body from the battery also.

Have you replaced the ignition module?

Is your module connected properly? Check the schematics.

Do you have the proper resistor wire in the power supply to the coil?

Apr 22, 2003 | 08:06 AM

balingwire

Thread Starter

Mountain Pass

Joined: Apr 2003

Posts: 248

Likes: 2

burning up pickup coils

We have replaced the ignition module and it is properly connected. I need to check the resistor wire in the power supply to the coil. I'm a little unclear on what exactly this is or where it is at. Could you tell me a little more about this if you get a chance. I'll check some manuals and schematics. Thanks.

Apr 22, 2003 | 09:03 AM

thelonerangerxlt

Posting Guru

Joined: Aug 2000

Posts: 1,984

Likes: 2

burning up pickup coils

Bailingwire, the resistor wire is under the dash, and is easy to see with a flashlight. It will be wired to the ignition switch, and on my 78 it is gray in color (although it might be red or pink). It is larger than the other wires, and will have writing on it.

An easy way to check it is to simply take a voltage reading from the positive coil terminal. With the key on, you should read around 7-8v.

It's purpose is to reduce current flow to the coil, allowing it to run cooler.

Last edited by thelonerangerxlt; Apr 22, 2003 at 09:08 AM.