w116 350 SE Engine start but immediately dies

Hi I´m new here, my name is David and lives in Sweden.
First, what a amazing work that you have done, Volker, thanks!!

I have bought a W116 350 SE 1974 with D-Jetronic. Some weeks ago.
The engine start up but would immediately dies. The owner before, showed me that he could get it running, if someone, at the same time, flap:es (quick pusches on the micro breaker) on the fuel relay or the main relay, I don´t know which.
Where to start? Is there a obvious start? Obvious problem that I shall start with?
ECU, Trigger conacts, MAP?

I have done a quick test on the MAP, as showed in the video here, and it seems ok.
Now, I´m looking at all wirings and rubber hoses.

I have the ECU 0280 002 007, and I have 2 spare in the trunk (I think that they have not tried them yet). Shall I start there?

Anyway, I will get through all the chapters here, and hopefully, I will be a little more lettered about the D-Jetronic
Again, many thanks for all this

Regards /David

Tjena David,

welcome on jetronic.org from Dr-DJet !

I do not quite understand what you mean by quick pushes in the micro breaker. If you can, please make a phot of what the previous owner did.

When a car des not start, we have three basic things to check:

1. Do we have a strong spark while cranking engine?
2. Do we have fuel pressure? Can you hear the hissing sound of fuel pump for 2 seconds after IGNITION ON? How high is fuel pressure?
3. Do we have injection. Try to touch injectors while cranking and feel if they vibrate. If you cannot feel, use Norbert's tool.

After that we can continue to search.

Well known trouble points:

• Worn trigger points. -> No injection
• Loose plus pole screw on battery -> everything works but injection
• Broken green cable from ignition distributor to ignition module -> no spark
• Kept ignition ON for too long -> Burnt coil, ignition module or resistors -> No spark or weak spark

Hi Volker and thanks, this is outstanding, I think, your website/blogg
With the blipping on the relay, I mean if you take away the cap of the relay and then pushing the breaker.

But, now we have looked a little more in detail and to answer on your questions:

1.Do we have a strong spark while cranking engine?
We have spark, the engine start with the cool start valve, I think we have.

2.Do we have fuel pressure? Can you hear the hissing sound of fuel pump for 2 seconds after IGNITION ON? How high is fuel pressure?
I think it is ok, we haven't measure the pressure, the fuel pump is working

3.Do we have injection.
We have no injection AND the trigger points are worn out, 1.9 mm at the best for all four cams. They don't touch the axle. Complete dry, no grease, what so ever. But how can the cams be that bad, the car must have gone really bad at the end. It is more than 10 years, I think, the last time the engine was running.
So, can I buy new cams from you or shall I buy repair set from BOSCH? What do you think? What grease shall I have, I think you have written that somewhere.

But is this the only problem? Because when we measure the contact to the "Trigger contacts" we can see 5 to 6 Voltage on 2 pins, number 6 and number 1 when we have the ignition on. Shall it be 2 pins or only one, and if so, do we have a problem with the ECU or a "short cut" in the wirings?

Many thanks and regards
/David

Hi David,

1.9 mm is indeed very little and explains the symptoms you describe. The relay you press is most probably the one for cold start relay. Engine will start shortly and die immediately without trigger contacts. Why? ECU will inject during starting the engine. When the engine is cold, cold start valve will additionally inject once.

ADVICE on newly bought cars: Check Bosch nos. on all installed components and compare with list in Appendix A. .

Regarding trigger points you have several options:

1. Buy from Bosch for 400+ Euro
2. Buy new cams from user althase here in forum
3. Buy measuring gauge form user nordfisch here in forum and readjust trigger points. That will let you use them a bit longer.

For option 2 and 3, contact nordfisch or althase via Private Message.

Whatever you decide, you should buy option 3 anyhow. It lets you measure wear and adjust even new trigger points. Believe it or not, we have seen misaligned new ones from Bosch.

Thanks, I will do so, I will contact them.

And the last question I wrote:

"But is this the only problem? Because when we measure the contact to the "Trigger contacts" we can see 5 to 6 Voltage on 2 pins, number 6 and number 1 when we have the ignition on. Shall it be 2 pins or only one, and if so, do we have a problem with the ECU or a "short cut" in the wirings?"

Thanks/David

Hi David,

there is a pull up resistor in ECU for each T.C. ECU only triggers on closing contact (negative edge) of signal when contact connects to ground (pin 12 from ECU). So yes, can be, no reason to worry.