burning up coils

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Oct 7, 2001 | 10:37 PM

ajv45

Thread Starter

New User

Joined: Oct 2001

Posts: 1

Likes: 0

burning up coils

I have a 79 f150 w/400. It burnt 2 coils up before I put an
inline resistor on the main power lead. this reduced power from
12.4 volts to about 9 volts. Now it doesn't burn up coils but it
only runs for about 15min and goes dead. voltage at coil goes
from 9volts to about 5.5 volts. After it sits ther for about 15 min
it will restart.
Have replaced:
coil
ignition module
voltage regulator
ignition switch
What else should I try???

Oct 7, 2001 | 10:52 PM

Franklin2

Moderator

Joined: Jan 2001

Posts: 56,997

Likes: 2,743

From: Virginia

burning up coils

What happened to the original resistance wire in the harness? Did you take it out? Or is it still in there causing you trouble. The resistance should be 1.05 to 1.15 ohms. If you put the other resistor in the circuit, it should be placed back in the harness where the original was, to give the "full voltage when starting" feature that is built in to the system.

Oct 10, 2001 | 11:57 AM

CougarJohn

Fleet Mechanic

Joined: May 2001

Posts: 1,396

Likes: 4

From: Cupertino

burning up coils

You replaced everything but the dropping resistor, which is likely the problem. It looks to me like this thing is getting hot, increasing resistance, and dropping too much voltage. Try replacing the resistor. Make sure that it has the proper power rating.