I have a 1979 F150 4x4 400 that has a strange electrical problem that just frustrates the you know what out of me. The truck will run fine for a good while and then just cut off mid run and then it won't restart. When I turn my key to the "start" position and try to start the truck, it will turn over repeatedly without starting and then when I release the key back to the "run" position it will try to fire briefly. Then I can turn the key back and forth from "off" to "run" and each time it turns over and acts like it wants to start! This goes on for a while and eventually stops and then I get into a whole flooding problem and eventually give up. I have checked and rechecked the timing and ALL connections that pertain to the ignition and starting systems. Can this be as simple as a new ignition switch? Does anyone have any tips or suggestions? If not, does anyone need a new truck?

Thanks

CE Webb
1979 F150 4x4 (unless this problem won't go away)

 

You have an ignition problem. Probably your stator inside the distrubtor is bad. When it heats up, it fails, when cool, it works. This is common with these. Every time you turn the ignition on and off you turn off the primary winding of the coil. These indices a voltage into the secondary side which causes a fire. This is basically what your primary ignition system does, turns on and off. You could have a problem with the ignition box too, mounted on your inner fender, but I would guess the ststor first.

 

CE until you can find your problem, push the foot feed to the floor until the engine starts. You wont flood it that way and it should start quicker.



John
jowilker

66 F100s
In the still cool hours of the night, you can hear chevys rusting away.

 

Thanks for all the info guys. I surely would have never figured out the stator unless I just got a wild hair and started replacing every part that I thought it could be. I will try both of your suggestions as soon as I can and let you guys know how it turns out.

CE Webb

 

When it wont start did you check to see that it had spark? I had a similar problem and it was the ignition module, I have had bad luck with the Ford replacement ones, so I got a NAPA Echlin unit and it has work a lot better, but I dont know why. I would check the all the wires, not just the connections look and see if they are cracked or look suspicious.

Dave

http://www.davesmonsterpit.com

 

I had almost the same problem with my truck last year. It would only run with the key in the start position. So I was kind of stranded (at the DMV no less). So what I did, was have my friend turn the key and hold it in the start position, and I simply removed the "Start" wire on the solenoid once the engine had started to disengage the starter. Then I took some electrical tape, and taped the ignition switch in the start position, and drove it home! Well I also had a situation with the shifter, because the column won't allow the shifter to move out of park when the switch is in that position. So I had to disconnect the linkage and do it by hand (with my friends foot on the brake). Kind of a cluster.... but it got me home. Anyway... it turned out to be the ignition module. They are pretty cheap so there is no harm in trying one. Good luck!!!

Steve

 

The problem is most likely in your ignition module. If not, it's in the ignition switch (key). But thats only about a 5% chance.

The ignition moduel has two wires that supply power to the ignition system. One is red and the other is white. The red supplies power while the engine is cranking, the white supplies power when it's running.

It's easy to check. Unplug the conector to the ignition moduel. (The one with two wires, red and white). Use a volt meter on the female conector that comes through the firewall (not the moduel side) and test each circut with the key in the on position, then cranking. White should have power while cranking and none when the key is just on. Red should be just the reverse (power when the key is on but none when the engine is cranking). If both are correct, the switch is fine and the moduel is the problem.

Pull one (or two) off a junk car from pick a part or buy a new one. Just make sure it's 82 or older! Don't worry if it's a Duraspark 1 or 2. (1's were a california only module for a few years but eventualy replaced the 2's. 1's had a hotter spark).

I keep a known good module around for ease of testing purposes. If I or a friend has a problem I just plug it in (they don't need to be grounded) and if the problems cured, I unplug it and replace the bad module with another one (not my test module). If the problem persits, then you need to start testing.

In closing, the moduels are prone to overheating. Make sure it's in a location that gets plenty of airflow. I'm willing to bet that you have headers! That's usually the kiss of death for the moduel. You can mount it on the outside of the radiator support by splicing in (soldering) wire extensions. If there kept cool, they never go bad.

You can replace your switch with a 74 or earlier unit, then the module only needs one wire conected (red or white), as the (points type) switch supplies power in the run or start position.

 

The problem is most likely in your ignition module. If not, it's in the ignition switch (key). But thats only about a 5% chance.

The ignition moduel has two wires that supply power to the ignition system. One is red and the other is white. The red supplies power while the engine is cranking, the white supplies power when it's running.

It's easy to check. Unplug the conector to the ignition moduel. (The one with two wires, red and white). Use a volt meter on the female conector that comes through the firewall (not the moduel side) and test each circut with the key in the on position, then cranking. White should have power while cranking and none when the key is just on. Red should be just the reverse (power when the key is on but none when the engine is cranking). If both are correct, the switch is fine and the moduel is the problem.

Pull one (or two) off a junk car from pick a part or buy a new one. Just make sure it's 82 or older! Don't worry if it's a Duraspark 1 or 2. (1's were a california only module for a few years but eventualy replaced the 2's. 1's had a hotter spark).

I keep a known good module around for ease of testing purposes. If I or a friend has a problem I just plug it in (they don't need to be grounded) and if the problems cured, I unplug it and replace the bad module with another one (not my test module). If the problem persits, then you need to start testing.

In closing, the moduels are prone to overheating. Make sure it's in a location that gets plenty of airflow. I'm willing to bet that you have headers! That's usually the kiss of death for the moduel. You can mount it on the outside of the radiator support by splicing in (soldering) wire extensions. If there kept cool, they never go bad.

You can replace your switch with a 74 or earlier unit, then the module only needs one wire conected (red or white), as the (points type) switch supplies power in the run or start position.

 

That is some great info Omni. I will admit that my next step was to replace the module(actually everything that I thought might be connected to the problem), but thanks to you I can check it instead. Unfortunately work and family obligations will keep me from trying anything or working on the truck for about a week or so. But I will let all know what happens.

As for what you asked before, I don't have headers and my module is mounted on the driver's side fender wall(above the tire jack mount). Is this not where it should be?

Thanks
CE Webb

 

The reason I thought you had headers is that is usually what knocks em out. A lot of my friends put on headers and suddenly have starter and ignition problems.

Yes, that's the stock location for the module. Should work fine there. You can put a few washers or even 1/2 inch nuts between the moduel and the fender wall so that it stands off just a little. That increases airflow arond the unit.

 

I am having the EXACT problem right now! I also have headers and had to replace the module a few years ago because it was acting up. I figured stator or module and in the process I just fried my starter today! Please let me know what you have found!
thanx

 

 

This may sound crazy but take along a bag of ice, or a 44oz fountain drink. when the truck starts to act up set the ice on the duraspark module for about 5 minutes. This should cool it down enough to fire. Duraspark uses two circuits to fire your coil, one is for cranking only and supplies a full 12-14 volts from the relay to the module, the other is "hot" from the run side of your switch which is at a lower voltage. when you release your key to the run from start position you will create a spark just for a second as the circuitry goes from start to run inside the module. This will cause the truck to "cough" as one cylinder will get a spark. I have used the above described fix to get my truck out of the woods on a couple of occasions, but when the ice melts your your s.o.l. Just trying to help....Bill

 

Im in agreeance with everyone else..I would bet that it is/was the module.I have had module problems in the past and this sounds like what i was experiancing.One thing though,for only $20 or so dollars a piece for good insurance..buy 2 and bolt them both to the fenderwell!...if you have problems..just change the connections and away you go!

49 F-1 (soon to be 460 powered streetrod)
50 F-1
83 F-150
94 Explorer
95 Mustang


If you listen on a quiet night..you can hear a Chevy rust...F-1s FOREVER

 

I had the same problem a couple of months ago with my 77 400, I finally replaced the coil and the problem went away. Never did get the coil to test bad though. Hope this helps.

BJ 1977 F150 4x4 400/C6