Hello, I found this forum today and I was hoping somone on here could help me find the problem with my 86 4cyl 5spd. The problem is this: After the car is nice and warm (usually after driving 20 miles or so on the interstate) the engine will cut out. Not instantly, it kinda diesels and sputters a little. Does not respond to the throttle at all. Turn the key off, count to 2, and it cranks right back up and your off again after only dropping 10 mph or so. INCREDIBLY annoying in heavy traffic! What makes this really interesting is that it WILL NOT cut out under a mid to heavy load. Only at light to mid throttle. It also cuts out pretty religiously every 3 minutes (unless your climbing a hill, in which case it will wait til you let out of the gas coming down the other side). It is also MUCH less likely to cut out if its dark, or during the winter when the outside temps are below 75 or so. I have tried everything I can think of to fix this problem: Fuel pressure is good, new TPS, new ignition modul (improved briefly, then went right back to it), new distributor, new O2, new MAP, new IAC (chasing a different problem). The only code it ever throws is O2 rich, and thats at idle (I also have a 100 rpm surge at idle, that may be due to the mild performance cam though). The symptoms would indicate an electrical problem (seems to be heat related), but why does it only cut out under a light load? It also occasionally acts up when I start it up warm, it refuses to idle until I drive a short distance (even 20-30 ft clears it up, but no amount of revving the engine in place will do it). This problem also seems to be load related. I'm at my wits end with this thing, can anybody help me?

First off, welcome to the forum and need I say the madness.

A couple of years ago I had a similar problem. Drove me nuts in trying to sort out. In the ended up being the fuel filter. Replaced it, everything was back to normal.

You may or may not have the same problem. Only a suggestion as you did not indicate whether or not you had replaced the fuel filter.

Welcome !! My money's on the fuel filter or a pump on its way out the door. Start with the filter.

I forgot to say I replaced the filter. It was dirty, but the problem didnt go away. I suppose it could be the fuel pump, but I've been having this problem a year and a half now. I would think it would have just quit by now. However, the fuel pump is probably the only electrical component that I haven't changed, so I dunno.

Yeah maybe vacuum ?? I'm assuming the injector checks out right ?

For a quick check, cover up your distributer with aluminum foil or saran wrap and get a water hose and run it over the engine WHEN IT IS COOL and listen for slurping noise. if you can pinpoint a slurping noise when you are running water all over the lines then you have found your leak.

Fuel Injector is new also. I checked for vacuum leaks awhile back using the "can of carb cleaner" method :-) and didnt find any. I did that to try to find the cause of my idle surge. I didnt think a vacuum leak would cause the cutting out, since it seems to be heat related, and the car always starts right back up.

What about the coil ? I bet you already thought of that. Man you just gotta chase this gremlin down.

Hmmm, hadn't thought about the coil. Maybe I'll change it out. I've changed everything but that.

Ok, I changed the coil this afternoon, and drove the car back home to Shreveport from Jackson. It still shut off on me, although not quite as frequently (maybe because it was a little cooler today). I would try replacing the fuel pump, but I really dont think its a fuel problem, it seems to be loosing fire, not fuel.

The only way to see if it's a fuel pump problem is with a pressure tester hooked up and taped to the windshield until the problem occurs. Their is a big difference in pressure and volume, You can have pressure with out volume and volume with out the correct amount of pressure.

[This message has been edited by Kekipi (edited 10-16-2007).]

The thing is, I dont believe its a fuel pressure problem. When it cuts out, its instant. No warning, its just off. With a fuel problem, I would think it would run bad for a short time (as the pressure went down) and THEN shut off. I probably will replace the pump though, just because its the only thing I HAVENT replaced. BTW, I forgot to mention I also swapped out the ECU awhile back with one I got on ebay, it didnt help either.

The Dukes have a known issue of the rubber fuel hose between the pump and the hard metal line failing with either a hole or an outright split. Before you buy the pump you might want to take a look first.

If it's not fuel related then you might try WINaldl. It's free software that allows you to see what your engine sensors are reporting to the ECM. It works on 84-86 Dukes but not on the 87-88 with DIS. There are some issues lately with Win Vista but if you have an old serial port laptop running XP then you are in business. An ALDL cable can be built for a couple bucks or bought from srat110 here or bought online.