I have a Plymouth Horizon that is having some issues. It must have been a month or so ago that the problem started. I would be driving and the engine would just die, just like you turned off the ignition. I had to turn the damn thing over forever to get it going again. The Unplanned Shut Down (USD) seems to happen regardless of speed, have had it die at idle and at highway speed. Usually only have one USD per day, other than that the vehicle has a strong idle and good pickup. My thoughts lead me to believe that the gasoline was crap. Keep in mind the car has 120000 miles and has been utterly reliable regardless of weather. Also, no fuel sensitivity has ever been noted. I ran several bottles of Sea Foam and iso alcohol (spread across a couple of tankfuls of gasoline)through to no avail. I noticed that after it sat for four days during Thanksgiving that the remainder of the tank burned without a USD. After refueling that USD problem started right back up. This suggests to me that the gasoline may have had particulate contamination. But the particles would have to be either small enough to make it past the filter and cause trouble down stream or so big that they would jam up the filter. Regardless, that amount of contamination should make it run like crap all of the time, not just a single USD a day. I pulled the fuel filter and sprayed out the throttle body throat. The USD problem gradually decreased in frequency. I refueled the other day and the damn USD problem was back in force.

Not sure where to go with this, I am out of ideas. I am hesitant to bring it to a mechanic due to the intermittent nature of the problem. I was kind of hoping it would go full failure so the mechanics could find the problem without killing me with diagnostic fees. Any ideas would be greatly appreciated.  

back in the pleostone era, I had somewhat the same problem with a car. Seems crud in the tank would plug the line. I'd blow it clear and it'd be ok for a while. finally I just cleaned the tank and that fixed it. A major PITA on the old '63, though.

Do not put more isopropyl alcohol in the gas!

Minnesota's gas is already chock-full of ethanol, so you shouldnt have to worry about water contamination.

The scenario you have described sounds WAY more like it is ignition-related.

Check your coil. Replace it anyway.

When a car dies "suddenly" and "just like the ignition is turned off", 99.9999% of the time it IS the ignition system.

When you have bad gas or injectors go bad, the car will suffer huge power losses, but RARELY "just die" like someone turned off a switch.

Um, it's spelled Pleistocene.

Heh,heh, you and your car have been in the liberal state of Minnesota tooooo long!!  Heh, heh, heh....

When was the last time you changed the fuel filter?

Take it to a car doctor....

OK, OK, I was trying to be polite in the public venue. It would be more accurate to say that my car, as of late, is a goddamn soup sandwich. [:D]

DevilsAdvocate: going to install a new coil today. Getting dark so it will be midnight basketball repairs for me. I will keep everybody posted...

Pick up coil is bad in distributor

No spark, no bang, no go.
Weak spark, go bang, but slow.
Go spark, but no bang, no flow.

Put in the new coil last night in the dark. Sucked, had the wife hold a flashlight so I could do the job. The cutting out was really bad that day, it was really wet and rainy. More evidence of electrical problems? Anyhow, damn thing cut out on me again on the way home today. Must not be the coil. However, after it died it was much easier to get the engine restarted.
The plugs, wires, distributor, and rotor are new as of this last fall. Could it be computer problems? I guess my car has some type of Flinstones computer on board. Or perhaps it is a failing fuel pump? Back for another round of conjecture...

vapor lock

hairline crack in the cap?Wet out does it cut out more or the same?

It seems to cut out more when it is wet. It was rainy on Wednesday and we had wet snow today. Maybe it was just coincidence though.
The cap is pretty well sealed, get that hissing noise every time I open it.
I am starting to think more and more it is the fuel pump. Seems to make the most sense, operated fine, cuts out, and then a strong turnover until it jumps back to life. The more I think about it it reminds me of when I changed over the fuel filter. Had to crank the hell out of it and then it suddenly sprang back to life when the lines got filled again.

This may be it.

Here is a rare problem with fuel systems, but I had a Volvo with a "failure to feed" problem -
the interior of rubber fuel lines deteriorate, the inside surface develops little flaps of rubber, and if one opposed the direction of fuel flow it can block the line.

If you get desperate and still think you are suffering fuel starvation, this is an easy and cheap enough fix.  Be sure to replace all of the flexible line in the fuel plumbing.

Gorto, Did you change the Ignition Coil or the Pick-Up that's under the cap and rotor? Next time it cuts out, check for spark and gas if you can.

I meant the distibutor cap.Look at it real close.It doesn't take much moisture to screw thinds up.

Dude, remove the fuel filter, throw away the car and get a new one.
Problem solved.

You mean the gas cap right?  Next time is dies on you try loosening the gas cap then trying to start it again.  Just a cheap shot in the dark..

I'm having a Bill Mauldin flashback...

I changed out the ignition coil, not the pickup.

Could be a weak battery.
I had my car die on middle
of the intersection.
I had a real bad battery.
Its matter of cleaning
the terminals and
getting a new battery.

It was pretty strange, removing that cap in this cold weather and getting such a hiss. At low temperatures like we have up here the fuel would have to have a monstrous vapor pressure, higher than something like than ether. I can try to find my original filler cap and reinstall it. Currently I have an aftermarket cap mounted on the car. Had it for several years now with no problems.

Will keep everybody posted.

A good test for ignition related problems is to fill a spray bottle with water, and in complete darkness with the engine runnning, mist all ignition components. Look for arcing.
Don't discount the parts you changed recently. I've seen plenty that were defective out of the box or that failed very prematurely.

Save the radiator cap, throw car away, screw new car onto radiator cap.

Gorto:

I'm not sure how the Horizon is built, but I had an almost identical problem with another vehicle involving the electric fuel pump located in the gas tank. It would just cut out, then if I waited a couple of minutes, everything would be fine. I recall there was a bit of a whining sound coming from the fuel tank in the final weeks before the problem started... My guess is the fuel system is the source of the problem.

I suggest finding a Plymouth dealer that will let you talk directly to a senior mechanic. Even an experienced guy working at the parts counter can probably point you in the right direction. If you're having this problem, odds are a few other people have had it as well.

I ran the car today, drove about 50 miles or so with no problems whatsoever. I couldn't find the original filler cap. I refueled and am going to try to "burp" the tank before I drive to see if insufficient ventilation is the problem.

I am having the car looked at by a mechanic on the 2nd. I just had the passenger side door handle break off today. The drivers side has been gone for at least a year. Not good.

Plinker: I am suspicious that it is a bad fuel pump. Seems to make sense. I will see if I can talk to a Chrysler mechanic before I bring it to the other guy.

1 spark

2 fuel

3 air

Check for spark when the car stops.

Hook up $34.00 fuel pressure gauge and leave on fuel rail. check specs for pressure.

Sound like ignition but this is the internet and I have been drinking so this advise it not to be trusted hic up

As a former Chrysler mechanic it has been my experience that the pickup under the distributor is the weak link on that system. Even today in a private shop I see a large number of bad pickups each year, however what usually happens after a while is that the car will eventually not start at all. I can't rule out the fuel pump because that is the second largest cause of such behaivor on those cars. The hissing from the fuel tank when you open the cap is quite normal especially when you are very low on fuel. Any mechanic will tell you that in order to check it, the car has to experience the problem while at the shop or they won't be able to diagnose it. Good luck Gorto, keep us posted.

When my Reliant was just conking out going down the road it was the pickup coil.

Would not be so bad but you loose the power steering/brakes.

Dennis Jenkins

Had to go for a short trip today and the car crapped out numerous times, usually in the worst places like the middle of intersections. I topped off the tank last night so this isn't a great surprise.
I am going to take a look in the Chitlin car book to see exactly how to remove this pickup coil from the car. Hopefully I can get a new one in there before I visit the mechanic.

Gorto, The pickup is very simple to remove. First you should disconnect the battery and remove the distributor cap and the rotor. The pickup is right there under the rotor, just lift it out of the distributor housing and unplug the connector wire. The two screws from the cap actually hold it in place. That's all you need to do. One thing to note is the position of the pickup, the magnetic pickup itself is usually on the right side, but note the position of yours before you remove. I am pretty sure thay can only go in one way due to the shape of the ends where the screws go in, but just in case eyeball it before you remove it. Keep us posted.

Just got the "hall effect pick-up assembly" installed in the car, the hardest part was getting the part from the store. Thankfully I got it before the sun went down. I have to go out of town with the wife here so I wont be able to do any real road time for a couple of days. Hopefully this will be it.

the K cars are death traps in a collision.  With 128,000 on it, I would suggest you drive it to the junkyard.  I darn near killed two teenage girls in a K car when they ran a stop sign.  Folded up like a beer can.  I would walk before I got into one.

Been on a couple of short trips with the car and have had no failures of any type. I think the problem is solved. I will call it good if I can go a week without a failure.

One or more of the sensors is toast.

Hopefully it was the pickup coil. If the problems return, check the fuel pressure.