Hello to all, 1984 380SE, recently the car stalls once in a while, and gets more frequent. From once few days to once few minutes, and now the car cranks, but will not start.

I have replaced the following:

Fuel pump, fuel filter, fuel accumulator and ignition coil. Ignition/spark plug wires checked ok (~1.1k ohms), and all spark plugs checked out normal. The car still cranks but won't start!
(Started a couple of times, but would either stall by itself, or immediately after touching the accelerator)

Pump is working properly, and fuel delivery rate is good.
Distributor and rotor were replaced by dealer 5 months ago.

Also I connected one plug to HT lead and earthed with a jumper lead, cranked the engine and there is blue spark, although sometimes none can be seen.

Jack 5 of diagnosis socket showed battery voltage, and voltage difference between 4 and 5 is 0 volts.

What could be wrong?
Could it be the igniion switching unit(002 545 26 32)?
Can anybody help me narrow down the problem or give me some additional diagnostic help? Thanks.

I don't know if your model has an OVP, or OverVoltage Protection relay. But it is the source of hot start problems. Do a search on "OVP" and you will find a wealth of information on the $50 relay that causes a ton of elusive problems.

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

Thanks G-Benz,
The model has an OVP, and after reading the search on that, looks like the OVP might be the cause. However she will not start no matter what (engine cold).
I will replace OVP first thing tomorrow and see if this fixes the starting problem.

Replaced the OVP today, and she still cranks but won't start...

Any help would be appreciated...
Thanks in advance.

You did not mention about the fuel pump relay. How did you test the fuel pump? Bypassing the relay? It may be the relay. The only way I know how to test the relay is to wait until the problem occurs and then bypass it or replace it with a loaner.

David

Hi be459,
I have bypassed the relay (by bridging jacks 7 & 8 in the relay socket), the pump worked, also delivery rate is checked at this time. I also have a new relay which I have tried as well, but result is the same. Pump is heard when cranking engine and for a short while after cranking.
Also after a few attempts, the spark plug tend to be wet with fuel, (is this normal?)

One other thing, there is spark from coil to distributor, but no spark at the cylinders (tested with HT leads and earthed spark plug) I don't know how old the leads are, but all have around 1.1k ohms, and connectors looks fine. The distributor and rotor are fairly new as well, are clean with no cracks. Is there anything I may have overlooked?

I don't recall if the spark plug wires have resistor caps at the spark plug end, but if they go out, then NO spark. The thing is, they usually don't burn out all at once, just a wire here or there. It sure sounds like the ignition coil though...

__________________
2009 ML350 (106K) - Family vehicle
2001 CLK430 Cabriolet (80K) - Wife's car
2005 BMW 645CI (138K) - My daily driver
2016 Mustang (32K) - Daughter's car

bill, you have identified the problem yourself. Spark to distributor, but no spark at plugs. It is either the cap or the rotor or the distributor end of the coil wire is broken. Or as a remote possibility the drive for the rotor is sheared or broken.

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.

*If* you own prior observation is correct (spark to cap, no spark to plugs) it is exactly as Jeffsr stated. If not however, one other possibility is the electronic ignition box itself. I am not sure if they were still in use on your model in 1984, but it seems very likely that they were.

They are usually very reliable, but I did come across one that was intermittent, and the symptoms are pretty much as you described. Also check the green wire from the distributor leading to the ignition box for continuity & good contact on each end. This wire should be kept away from the high-tension leads as well, just in case someone re-routed it. (Even though the wire is shielded, the high voltage wires theoretically can cause an induction current that would foul up the signal. This will *not* be your primary problem though.)

Yet another possibility lies with the ballast resistors. It is possible, yet very rare, that the resistance coil has fractured. This will allow voltage to pass when they are *just* touching, yet any vibration, or the heat that is generated, can cause it to shift, thereby opening the circuit. The other (not so) long shot is the coil in the hall-effect unit itself, located inside the distributor.

Please let us know what the problem was when you find out.

Good Luck
RTH

[Edited by RunningTooHot on 07-20-2001 at 06:27 PM]

Fiddled around a bit today, and cleaned up the poles in the inside of distributor cap. Tried a few times, and got the engine to start!! However stalls pretty soon after, usually it's hard to start again. Sometimes you can rev the engine all the way to red line, but sometimes it would stall upon attempting to revving it to keep the engine going. Battery got low from all that cranking before the engine really warmed up.

Two observations today:

1. Some black solids, from sand sized to say 3mmx2mm, came out of the exhaust pipe, now this doesn't look good...

2. The distributor end of the green wire (to ignition module) is cracked, I cracked it open while removing for inspection. However all connections seems still OK.

I will replace the green wire tomorrow, and see how it goes. Meanwhile any suggestions are welcome and appreciated.

Thank you all for your help and support.

Greetings,

I got a second hand ignition module today, plugged it in and the car started straight away. Haven't replaced the green wire yet. Drove around the block a few times, then I noticed the RPM would drop very low (but didn't stall) when idle in gear or A/C swtiched on, which wasn't there before. But at least she's now drivable!

Thank you all again for your help, deeply appreciated.

Best Regards,

Bill

Bill you car is blowing a bunch of accumulated crap out of the muffler. Unless it's metal, don't worry. We all produce solids at one time or another. I still think you're going to have problems with your ignition system. If the high voltage produced by the coil is weak, you will have trouble with rough idle and hard starts. The ignition control module manages dwell, timing and the like. The coil, distributor (cap), rotor and wires manage getting the spark to where it has to go. If the module is sending low voltage pulses to the coil according the ECU inputs, etc., then the coil HT voltage will be proportional to the input voltage. For your peace of mind, find a tech you feel comfortable with and get the engine scoped and see what you are actually getting from the ignition system.

__________________
Jeff Lawrence
1989 300e
2000 Dodge Grand Caravan SE
No matter what you fix, there will always be something else to fix..
"Warranty" is just another way of postponing the inevitable.