Electrical Ignition Problem - Just stops ?

[sawdrl]

After 3 months of trouble free ownership my 1995 4.0 Chim has taken a turn for the worst. First of all I got intermittent stopping of the engine for no apparent reason. It would just stop while driving along, but it would start up again either by just bumping it or on the key. Its got more and more frequent to the point whwre I now don't dare take it out. When I start it from cold it fires up no problem, it will then tickover fine and even respond normally to throttle blips, but after about 2 minutes it just stops............no stuttering, no misfiring, it just stops stone dead as if the ignition is suddenly swithched off. It will start up again on the key though, but the problem just keeps on happening. Holding it at 2 or 3000rpm for a while gets the same result. Revs can beheld steady at say 3k, then as the power is cut the needle just drops to zero instantaneously. Any ideas fellas ?..........don't much like the idea of paying £75 per hour to have the main dealer investigate if without checking for obvious things that the mechanically able out there would know about.

Steve W

[Li'l Pugs]

Usually, running probs always gets the same response:

Stepper motor.

Have you cleaned yours recently ?

Apart from that I'm afraid I'm a repair numpty.........

Sorry

Paul

[chimtvr]

sounds like you are loosing power to the coil check the connections to the coil are good (not loose) look at the coil carefully on one side it has a little + sign get a meter or test light and check it has 12v all the time the engine is running email me with what happens and ill talk you through what to do next
Dave

[poorpeet]

Sounds very like a problem I had with my 93 4 litre.
Should be easy to find out if its the same.
Take out the bottom of the passenger footwell so you can see the fuses.
You should see a couple of fuse holders just hanging from their wires. Check both fuses. Mine were ok but when i checked the condition of the fuse holder contacts one set was black with corrosion. I cut it out & put in a replacement from halfords. This cured it for me.
I think these loose fuse holders pick up damp from the carpet & corrode.
At least it's an easy one to check.
Best of luck

Pete

[GreenV8S]

The first thing to check is whether it is a fuel or ignition problem. From the symptoms I would *guess* fuel, but you need to be sure. Each time you switch the ignition on you should be able to hear the pump running for a couple of seconds. If you don't hear this, you have a straight forward trouble shooting job in the power supply to the fuel pump. Find any convenient 12v supply (cigar lighter socket, battery +ve post etc) and run a fused 12v supply straight to the 12v side of the pump. Most likely the pump will now run continuously and the problem will go away. (If not, you have a bad earth to the pump or a knackered pump.) Next you need to isolate the fault in the pump supply. The most likely candidates imo is the relay. This is a metal cased Bosch relay on a flying lead close to the ECU. When these fail they produce exactly the symptoms you are seeing. The easiest way to test for an intermittant failing relay is by substitution, but check that the socket connections are clean and fit properly as contact resistance here will overheat the relay and make the new one fail too. If it isn't the relay then check the fuse holder too. If these don't cure the problem, check the inertia cut-off switch. These can corrode and become unreliable.

Assuming that your hotwiring test does show that it is a fuel pump supply problem, you now have a fix that you can rely on to get you home.

If the pump is running OK then it is more likely to be an ignition system fault. Troubleshooting this system is slightly more difficult and you may just want to give it an ignition service and replace all the usual consumables plus the ignition module, otherwise time to call in the experts.

[chimtvr]

if the rev counter drops straight down dead it is ignition as the rev counter is driven by the ignition coil if its a fuel problem the rev counter will drop with the engine revs check that first it will save you a load of time
Dave

[deeen]

Thanks G-V8S and Chimtvr i am literally sitting here making notes off this thread!

[sawdrl]

Thanks for the advice so far guys..........plenty for me to be checking out next weekend. The rev counter needle does definitely drop like a stone a split second before the engine dies...........thats what leads me to think it is more likely to be an electrical problem too. Cleaned the stepper motor out last week...........made no difference at all !

[pebbledash]

My griff had this fault, took ages to track it down, in the end I found it was the main relay (the one in the pasanges footwell on the loom) it had a nasty habit of droping out (not physicaly but electricaly ) and efectivly killing the car.. it was not loose but just a dogy connection, so I closed all the spade connectors in its plug slightly, and used swich cleaner ont the contacts, not had a problem since, it also cured my intermittent missfire and other Weired running issues..