Engine stumbles/cuts out over bumps :(

[bloodsnot]

What I would guess would be a likely thing to check out, is a shorting fuel pump. My guess is there is an exposed fuel pump wire, and just through movement it might be shorting to ground then the pump stops.

I do think that it has something to do with the fuel pump connections because of the temporary fix attained by simply re-seating the boots. The problem came back a bit later during a string of rainy days and perhaps the moisture exacerbated things? I've since fumbled around with the pump connections and it's been trouble free so far. We're still on probation, though..

Another Euro-victim here, '86 M20B20, LE Jetronic and Telefunken ignition. OP, is your car the same? Does it have an actual distributor and a water heated idle valve, and have you realized that the Bentley manual doesn't cover our cars?

Mine's an '85 M20B23 with LE Jetronic though I've never heard of Telefunken ignition before. It does have the actual distributor and the "Additional air slide valve" that closes as the coolant temp rises (see my first few posts). The Bentley covers quite a lot of things common to all E30's but I do have to refer to a UK edition of the Haynes manual for wiring diagrams and what not. It's a shite manual but at least it's specific to the Euro model.

If your car is anything like mine, that CPS up front has nothing to do with engine management, it's just for shop diagnostics.

Hey that's good to know. I was curious about why the CPS was hard-wired right into the bottom of that diagnostics connector. Was thinking perhaps it was just wired through it and as such was going to be a pain to change.

I'd be looking for a loose connection or bad ground in the ECU circuits, the ignition system and lastly the fuel pump. .
When and if the car is running, start pushing wires around trying to make it stumble. I think the 323 had a socket just above the left mounting bracket, under the intake manifold, maybe start there.

I did try to induce this problem by jiggling wires all around under the hood and haven't been able to do so. I haven't tried to induce it by knocking around the fuel pump or by opening the glovebox and bouncing the DME around. I don't recall specifically targeting the stuff right under that diagnostics connector/socket by distributor and manifold... I'll give that a shot.

Thanks everyone for your advice! So far she's been behaving but without a clear resolution.. I'll update this thread if I can induce the problem again and determine a more specific solution :-/