Warms up and stalls?

[Anonymous]

My car started acting up today and had I not been only going on a short trip to the store probably would have stranded me.

Car will run fine until about 15 minutes, then it will just start dropping the rpms and die out and won't stay running unless you floor it. I can wait for 5 minutes and it's normal until about 15 minutes of run time and it dies again. Lucky me, the first time it did it was on a hill and finding out you no longer have power brakes on a steep downhill is no fun! :help:

Well, I made it back home safely and have no clue as to what it could be. Doesn't act like a vaccum leak as it doesn't idle rough, but it does feel like the ignition is backing off for some reason. Maybe a ignition part is heating up and stops working?

What could it be?

 

[MustangSix]

Is your vacuum advance routed thru a vacuum temp switch on the thermostat housing?

 

[Anonymous]

Were you driving on a straight stretch when it died?
Because, it sounds like it could be something in your gas tank (trash, plastic bag, ping pong ball, etc. etc.) - It would allow your car to run fine on short trips and stop and go, but if you drove without stopping for a few minutes, it would kill your engine (with continuous driving it rises till it block off and restricts flow, you stop, it falls and clears itself up again - being the reason why if you let it sit for a few minutes it will start back up).

Hope this helps, let me know

-Levi

 

[Anonymous]

Jack: Yes, it is.

Levi: It happens even when it's parked and idling. The tank was cleaned and sealed when I replaced the sending unit in it about two months ago. I don't thnk I dropped anything in it before it was reinstalled but I could check.

 

[63Futura]

I had the same type of problem with my Falcon and the old gas tank. The problem was that the screen filter on the pick-up would clog up, and the car would die. Give it a few minutes, and it would be fine for a little while, and then die again. I finally cut the screen off entirely, and the problem never presented itself again.
Now that I have a new tank and pickup, I don't have to worry about it.

 

[MustangSix]

Check that vacuum routing. When the engine is cold, the passages do one thing, when warmed up they do another. Could be that as you go from cold to hot the advance changes on you, causing the car to die.

 

[DaGr8Tim]

If the coil's mounted on the block, could that be a problem area?

 

[Anonymous]

Vaccum hoses are connected up the right way, at least according to my Ford manual. I'm going to try replacing the valve that Jack mentioned.

Coil has been moved to the fender as I don't like the kind of heat the block gives off

 

[BIGREDRASA]

You moved the coil, but is it new? Sometimes those electrons in the can just go stircrazy, and must be replaced with a new can (coil) of electrons.

 

[Anonymous]

Coil is almost brand new, it's only been about a month since I replaced and moved it. I've also tried swapping out my MSD Duraspark 2 box for my brother's and a regular DS2 box, which are both known good ones and no change. I've also disconnected my 6A and went to regular ignition setup and still no change.

Things I've replaced or swapped for known good parts:
Coil
DS2 box
Distributor
Plugs (have known it to happen with bad plugs)
New Vacuum hoses
New vacuum check valves
Made sure the carb is sealed, it is
Made sure I don't have any vacuum leaks, none

Today I'm going to pick up the valve that Jack mentioned as I think it is the culprit. If it's not I'm going to send it in and find out it was something cheap and easy to fix and be overcharged for it. :x

 

[BIGREDRASA]

Just for the heck of it, check your voltage at the positive terminal of the coil, before and after. Maybe you're having a problem with your ballast resistor. It does sound electronic.
Then again, there's the old mechanics' saying that if you think the problem is carburetion, it's probably ignition; and vice versa.

 

[gtm1086]

Plugged fuel filter?

 

[Lazy JW]

It sure sounds to me like it's running out of fuel. Having driven mostly old junkers all of my life, I've encountered plugged fuel lines, debris floating in the tank, inlet screens that get clogged and when the fuel pump sucks fuel it collapses the screen(VERY difficult to troubleshoot!) weak fuel pumps,etc. You can narrow this down by taking a friend along for a test drive, and when the car dies, have your friend crank the engine while CAREFULLY spraying a small amount of starting fluid in the carb. If the ignition is bad, it won't run. I'm guessing that it will run on either.
Lazy JW

 

[Anonymous]

Vacuum temp switch was bad, when the car warmed up it would change the advance and the car would die. Replaced it and I'm good to go. Thanks for all the help! I'll remember the suggestions if another of my family's cars does this.

 

[BIGREDRASA]

On the topic of VTS, your dizzy should connect to ported vac at normal temp, and manifold vac at high (overheating) temp. In other words, under normal circumstances, you should always have carb ported vac to the dizzy, not manifold vac. 8) Is that what you have?

 

[Anonymous]

ST80-
before you quit looking under the hood, check the EGR valve. I had the same problem on & off for 2 years before I finally discovered that the spring that closes the EGR valve was cracked. This would sometimes let the valve open after the engine warmed up, but then it would not close. When it won't close, the engine won't idle - I'd have to keep it nearly wide open to make it run. After shutting it off for 10 minutes, the vacuum system that runs the EGR valve goes into "cold" mode and stops working until the next time it warms up -then it would start all over again. Sometimes, though, it would work fine.

The EGR valve has a little shaft in it that you can reach with long needle-nosed pliers. Pull off the vacuum line to the EGR valve, plug it, then grab the shaft while the engine is running and push it back & forth. You'll see the engine increase in speed when it closes the valve and slow down (or die) when you open it. If it's like mine, it might not close all the way by itself.

By the way, if you have over 50,000 miles on the valve, Ford says it's shot. I have found improved performance on both of my 1979 Fords by replacing this valve at 40,000 mile intervals. It only costs about $20.

 

[Anonymous]

Hmm, good point! I'll guess I'll get a new EGR, since it looks like it hasn't been replaced at all. Thanks Mark!

BIGREDRASA: Yes, ported vacuum going to the PVS (finally found the right name for it) when cold and manifold vacuum when hot.