I Have An 84 F150 That Will Not Fire Until I Stop Cranking. I Replaced The Ignition Switch But Problem Still Exists. I Could Crank Forever But It Only Starts When I Let Up On The Key. Starts Fine With Key On And Jumping The Solonoid. Any Help Is Appreciated

Gary

 

Sounds Ignition switch plug may be bad.

What Ignition System do you have?

 

It is a Duraspark II ignition

 

I don't know duraspark but I had a similar problem and it is an easy fix if you have the TFI ignition module that is attached to the distributor.

On the TFI module, there are separate run circuits for cranking/Start and normal/Run. On mine, it would run in start but not normal. Sounds like you have the exact opposite. Change that module and your problem should be solved. The power to the ignition is not getting there when cranking but once it switches to normal/Run mode, it is getting the required juice.

Maybe someone that knows Duraspark will chime in and if you don't have the distributor mounted TFI, will know what takes it's place in a duraspark.

Lee

 

The Duraspark module has the same type of start and run wires, as the TFI. I suspect the start wire to the duraspark is either suspect or the module itself. Have the module tested, and/or Replace the module.

The same start wire hooks to the starter solenoid so you do have power going through it from the ignition switch.

I always keep a spare in the truck, cause when the duraspark does go wrong it can cause strange things to happen.

 

There is not much that can cause this, the Ignition Switch, its Plug, Module, and the wiring to them.
Check the white wire circuit.
Here is a diagram of the DS II System.

 

I've had that problem and replacing the module usually fixes it.
On the same note, I have a weird one going on with my truck. 83 F250 4x4, 460, everything stock. Just quits on me the other day so I changed the module. It ran for about 20 miles and quit again. Friend of mine says the stator will cause the module to go out. Anyway, I have vacuum problems so I just changed the whole distributor with factory remanufactured, changed the module again, she started and ran great for about 20 minutes this time. I drove it about 2 miles, shut it off for a minute, then when it started it sounded like it was missing, sorta duh duh duh instead of brum brum brum at idle. I suspect the module again but don't know what's causing them to go out.
One possibility could be the fact that I am trading these modules in at Autozone for new ones cause it's got a lifetime warranty. They could be bad as any I guess.
Tell me ladies and gentlemen, what do you think?

 

Put a test light on the "I" terminal of the solenoid while cranking. No light, bad solenoid.

 

Chief, We had a similar problem in an '82 E350. It turned out to be a bare wire that was shorting and causing the modules to burn up.

 

I suspect it causes problems as it reaches full operating temperature.....expansion.
Now what "it" is, I haven't a clue.

 

pfogle, what wire did you find bare? Was it one from the distributor, coil, module area or another?
I remembered today that about two years ago I worked on one just like this for two weeks. It would crank and get a little fire, evidently not enough though, start for a couple of seconds and then die. Believe it or not it turned out to be the starter selenoid that time. After studying the scematics for a Duraspark II for quite some time I think I finally understood why. It does more than just pass 12V to the starter. It has to pass the start voltage to the module, etc...
Could be my problem again. I have three or four old ones but not sure if they are good either so, I'm just gonna wait till tomorrow, take the module back to you know who and have it tested as well as go across town and get a new noid....
Best thing would be to do the troubleshooting and quit changing parts but, the noid and coil are all I have left, lest I forget wiring....
What do you fellas think??????

 

It sounds like the solenoid is not delivering the current to the I terminal to supply power to the ignition. Since it starts, after the key is released the ignition switch is then supplying the voltage to the ignition and the momentum of the engine from cranking carrys on long enough for it to start.

To test this, just put a small jumper between the S and I terminals of the solenoid so that when cranking, the start signal will also supply juice to the ignition. Try it, you'll like it.