I joined this site for the sole purpose of finding help for my truck problem. if you guys can coach me, i will be eternally in debt.
2 days ago on the way home, my 1976 f-150 just died on the road as if the key had been turned off. since then, it will crank and start as long as i have the key in the crank position. as soon as i release the key it dies. i replaced the soleniod yesterday and it still won't stay running after i start it and release the key. today i replaced the ignition switch. still the same. somebody please help me figure this out. i have to work in the morning and i need my truck! it is not the battery, it cranks and starts just fine. it just won't stay running after the key returns to the on position. it looses all spark.

 

Welcome to the site

In my eyes you have started off great just by putting the topic in the title.

You need to get a multi-meter or test light and attach it to the + post of the coil top test for power in different key positions.

If you have power..how much with key in RUN ?




You replaced the Ignition switch..did you also replace the key tumbler?

These problems are usually a Key Positional thing.




Do the power to coil test ..then report back.


Here's your ignition system.

 

Hey Dennis, thanks for answering so fast... let me print your response out and give this a try. No, i did not replace the key tumbler, just the casing with all the contacts. i never would have dreamed the non-electric tumbler assembly could possibly be the problem.
I'll report back after i try your suggestions
Jack

 

There is a little tab/nub at the end of the tumbler that changes the position of the internals of the switch.
shown here.

http://info.rockauto.com/SMP/SMPDetail3.html?US23L.html


If that is worn out, it won't work properly.

 

Hey Dennis, I put a test light on the top coil post and it has juice in the run position. In fact, it has juice in all positions except the off position.
I never installed the key tumbler assemby in the new ignition. I am sticking a screwdriver in the new ignition switch and operating it like that.
Any thoughts?
Jack

 

It should be on the + terminal of the coil.

That secondary circuit (coil wire to dist) pumps out 15,000 volts

Can you take a picture of the end of the key tumbler to show me how worn it is?

Also, does the tumbler click the switch like the screwdriver does ?

You must have seen "Gone in 60 Seconds" ?

 

lol! In fact I did see it, however I'm not that good if can't get a '76 truck started.
The nub at the end of the tumbler is pristine. looks like it just came from the factory. I don't have a way to take a pic of it, but believe me, it's like new, just like the photo you sent. I'm stymied on this... haven't got a clue what the problem is.

 

So it won't start when you use the screwdriver either ?

 

Yes it starts just fine, it just won't stay running when i release the ignition and it falls back to the "run" position. As long as I leave it in "start", which makes the starter bendix grind while it's running, it runs just fine. It's only when I let the spring-loaded mechanism in the ignition switch go back to the "run" position is when it dies like the key has been turned off. Weird, huh?

 

Well that is a positional thing.
Perhaps that new switch is faulty.

what is the part number of that switch ?

I have the prove-out (ignition Fault) test for an 78 but not a 76.

Here it is.

http://www.clubfte.com/users/mil1ion...nFaulttest.JPG

 

Hey Dennis, please don't tell me you gave up. I'm in a pile of crap here and I really need expert advise. If you are as perplexed as I am, perhaps you can refer me to someone?? My cell number is 972-898-1918. Actually, this is a friend's number who is here now trying to help me with this. I'm too broke to have a phone.. that's why I drive a '76 truck that won't run now.

 

Holy Moly, I think I found the problem. Let me run this by you and let me know what you think... the prove out diagram you sent says that the ignition switch casing should be grounded. I don't have it grounded, I have it just swinging free under the dash because it is so hard to take in and out of its mounting spot on the dash. perhaps if I ground the switch it might work. What do you think?

 

neutral safty switch

 

Armstrong....

The starter cranks okay..that rules the NSS out.

sailor, I haven't left you.

If you have power to the + terminal of the coil using the key, the circuitry is fine.

Try putting a jumper wire from the + post of the battery to the + terminal of the coil..and start the engine.

Don't run it too long like this though.

 

just got back inside from another frustrating failure with the truck. that didn't do it. I'm going back out to try this new suggestion... stay tuned!