'91 Ranger, 2.9L, 5 speed, 2X4. While driving at varying speeds, including city and highway, the engine simply dies as if the key was turned off. No indication before or after that there was a problem. Then, if rolling, it restarts itself and I continue on. Of course, if the situation occurs at or near stopping, the engine must be restarated with the starter. This condition occures at random, at any temp, and at any speed. Sometimes the condition is associated with the check-engine light and sometimes it's not.

Ford dealer replaced both coils, all eight pulgs, and a host of associated modules & sensors because of a similar problem about a year ago, but this new problem does not reproduce any codes when checked. Even had the dealer install a "co-pilot" to activate and remember the condition, with no codes reproduced there either after a three-week useage.

So, seems to me it's not a module/sensor problem as much as it is something basic and simple. Therein lies the problem. Everywhere I take the vehicle, the first and only thing they want to do is check for the codes. But none are present, so the troubleshooting stops there. I'd certainly be most appreciative of any input ya'll might have. Unless there's a ghost turning my key off and on as I'm driving, this one's really got me (and the mechs) stumped!

 

have you checked into a possible fuel system related problem?

 

When it dies do the idiot lights come on? If not it's probably a bad ignition switch.

 

The idiot lights do NOT come on. The event happens pretty quick between dead and restart - especially at speed. Are you saying the switch may be opening just long enough to simulate a key-off condition, and just as quickly closing again allowing the engine to restart?

 

JUst a guess but the symptoms do seem to fit a bad ignition switch. If it was mine i'd swap the switch & cross my fingers.

 

Thanks... I'll give it a shot and see what happens.

 

Hello all... I appreciate the replys on my question, and I replaced the ignition switch (the electronic part) and still have the problem of running, dying, running, dying, etc....

The problem occurs at any temperature, in any gear, just after starting in the AM, or after running for an hour or more, with the A/C on or off, and on acceleration as well as decelaration. Generally, the engine just simply dies and then restarts (if rolling, in gear) with absolutely no indication of the problem either before or after the event. It is truly as if someone turns the key off and immediately back on again. I even bypassed the inertia switch just in case it was sending faulty signals. Any more advice?? What fuel system problems may be causing this condition? I'm Stumped!!!

 

i may be wrong but it could be a loose/bad connection or short somewhere. check all the wiring harnesses for connection and check the prongs inside to make sure there ok. also check the egr valve to see if it is clogged w/ carbon, that could kill the engine if it is.

 

How likely is it that it would stall while idling in your driveway? If it would do that you could, for one example ground the fuel pump relay & see if the pump runs. Do you have wiring diagrams for the ignition & fuel pump circuits & a VOM? Like elconquistador sez check the connectors & grounds. A clogged EGR might cause pinging, but not likely to cause stalling.

 

Have you replaced the fuel pump relay?

 

Do you get any codes from the ECU?

 

Ken, since this thing has been checked for codes numerous times & even had a "flight recorder" installed with no results. does that point in any particular direction?
Geoman, check out this link, it will tell you how to very simply ground your fuel pump relay the next time it stalls.
www.superhighoutput.com/tech_view.php?id=5 Doing this will check everything in your fuel pump circuit from the EEC power relay to the fuel pump. Try doing it now, so you are ready to go with this test the next time it stalls. When it stalls dont touch the ignition switch, just pull over & connect a jumper wire from the negative post of the battery.

 

If you don't pick up anything from the ECU then it's beyond its area of control like loss of fuel pressure & secondary ignition, I'll keep thinking for other things.

 

Thanks Ken and in that case i guess grounding the fuel pump relay would be a waste of time. Geo man disregard my last post.

 

Engineer at work had a poster in his office that said "Look For Something Simple Stupid"!!!!

So many times I found Dan.s poster to be right on target, so I'm prone to begin my troubleshooting with the most basic stuff first.

As has been suggested I too thought of the ignition switch, but as that didn't pan out, I'd begin with ground connections.

Battery, computer, Coil/pack, fuelpump, body to engine, battery to engine, (the last one is probably ok if it's cranking strongly), in short anything having to do with fuel or fire.

If you suspect one in particular, but find it difficult to test, just make a parallel portable ground wire, with clips on both ends & see if the problem stops.

I like to run one end of the portable ground all the way back to the battery.

Just some ideas from the peanut gallery.