1971 250 CE CUTS OUT AFTER FEW SECONDS

Hi Old Mercedes Afficionados,
My wifes 71 250CE cut out the other day and wouldn't start despite me cleaning points etc. It seems to have good spark while turning over and
will start and idle nicely every time for about two seconds and then cut out. It does this over and over, it seems like fuel to me but I know nothing about fuel injection.
I can hear the electric fuel pump whine when I turn the ignition on and the manual suggests replacing the element in the fuel filter but this car doesn't have one as indicated on the left side of the engine.
Does anybodyu have a suggestion for something to look for before I have it towed to the workshop? Its a long weekend so I have some time to kill.
Regards,
Rob Emery
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Rob
Stard under the car where the tank is and follow the fuel lines. If it starts then cuts out, it could well be a bad filter or fuel pump related.
Regards
Al

the
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What I think is happening is you lack continuity at the trigger point circuitry.What could be happening is the engine is starting off of the cold start injector and then when key is released,the cold start injector shuts off! The function of the trigger point is to provide the D jetronic with a synchronizing signal to open the injectors.This is located in the distributor and look like a set of dual ignition points.
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PS these trigger points are good for about 100,000 miles if this helps i.e. when were they changed,if ever!
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Oh yeah, I guess it would help if I told you how to test trigger points huh?Disconnect the ECU harness,and then check the resistance between the ECU harness #12 and #21 and then #12 to #22.One should show an open circuit and the other a low resistance.Now heres the fun part,turn the engine (by hand) 360 degrees and the readings of continuity should be vice versa! If not,go to the trigger points themselves and perform the same test to the letter from here.This will tell you if it is a problem with the harness itself or the trigger points! Note:do not attempt to start engine until everything is reassembled!
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Hi,
It did something similar a while ago and the mechanic checked those trigger points and said they were fine. That time it turned out to be something (a dry joint or whatever) with teh "computer". I had to smile at the thought of what sort of computer was in a 1971 car. I wonder if its that again.
I traced the fuel line from the tank and found a couple of what I think were filters, bell-shaped in line one of the way to the injectors and one on the way back. I removed one and it seemed very clear to blow through. I turned on the ignition while a hose was off and there was good fuel pressure.
I'm wondering if its the computer again... if so it counts me out for a repair.
Thanks for your consideration people.
regards,
Rob

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Reporting back... the mechanic found that the plastic cover on the trigger points had been broken and he wondered if the bits of plastic had interfered with the points. Other than than needing new plugs and the point adjusted he couldn't see anyting else wrong. he reckoned that it was out of tune and that's why it wouldn't start but it must have been something more than that because each time it cut out it was like you had turned the key off while driving along and then it wouldn't start. Also rembering it would start first turn of the key but only run for a few seconds.
Other than that he couldn't find anything but spent some time telling us how old and tired the engine was and that we should get rid of the car. "Kaput" I think is how it described it I think he may have been a bit of a perfectionist. It only burns a litre of oil between changes and starts first time everytime.
Hopefully it was the trigger points because we're now a bit nervous about using it when we have to be somewhere on time.
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Its not "Kaput" but rather than him being a perfectionist maybe he is a defeatist at this point! I still think its the trigger points or in the harness between the trigger points and D-Jet ECU,but this is just my opinion.By chance,did the thumbscrew on the ECU get turned for whatever reason(CO adjustment)
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The thumbscrew wouldn't have been turned to cause the cutting out because nothing had been done to the car for weeks when it first cut out. Klaus (what a great name for a Mercedes mechanic) may have made some adjustments to the CO while tuning it. Its been running fine for a couple of days so my wife is just beginning to trust it again but it will be a while before it reagains it former position in her esteem. She was a little offended at the mechanic's description of her precious Merc as being kaput.

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