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940 (1994 Bosch) no-start diagnosis 900 1994

posted by  someone claiming to be franje on  Tue Jun 17 12:03 CST 2014 [RELATED]

Hi folks, can I ask for a little help diagnosing my beloved 940?

I turns over, but does not start. The rpm tach, with rare exceptions where it jumps a little, does not move. I can't see a single spark at the plugs.

-I have tried jumpering pin 30 and 87 of the RSR (I have always heard the pumps though and get a fuel shower when I open the check valve at the rail)

-I have tried two other Ignition amplifiers from the junkyard, all three have nearly the same ohm readings between the pins (is there a right way to ohm-test them?)

-I have replaced my CPS which had no continuity on one outer pin with a used one that has 170 ohms between center and both outer and 1 ohm between the two outer pins.
The plug where the CPS gets connected to, has about 3V to ground on one of the pins when the ignition is on. The other two have 0V.

-The coil resistances are within the specs. I have 12V at the blue wire which drops down to 10-11V when turning over.

-I have NOT yet replaced the spark wires or looked into the distributor. I can't imagine these parts to fail so completely that there is no spark whatsover. But I might be wrong?


Any opinion is appreciated! I have read through many related posts, but I feel stuck now.

[The whole thing started with rough idling and hesitation at acceleration under 2000 rpm, and some misfires above that. At some point, it wouldn't start anymore. Somewhere in between I got it to start and it ran on 2 or 3 cylinders for a while and then died. Since then it is the above scenario.]

One thing I'd like to do is testing for spark right after the coil. What's the best procedure to do that without much equipment?

Thanks,
Franje





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