Intermittent Rough Running and Hesitation 400i

My first thought was water in the fuel, so I ran some E10 through to soak any up. My next thought, as it seemed to happen after about 45 mins of running, was that the Dinoplex was getting hot, and on the way out, so I installed an MSD. On my first run, it happened in a few minutes, so that wasn't it either. It feels like an ignition fault - sudden onset of very rough running, no power, won't rev, but will suddenly run perfectly with a burst of smooth running and power, before dropping back into rough running again. In the past, it sort of goes away after a few minutes.

Thoughts? I've only got coil and distributor left - I really don't want to look inside the distributor, it looks big and scary.

 

Aus delivered RHD - another problem with the new Fchat - hard to see where the poster is from!

I thought of that, but it seems to be a global problem for the whole motor. AFAIK, a fuel pump will cause loss of power, but the engine runs smoothly on one bank.

Like I said, the distributor is big and scary (and hard to look at). The only thing more scary is the fuel distributor. I'll have to bravely take off the cap and have a look with a mirror.

Duh, what's your special subject - the bleeding obvious? I've been waiting for your bus to be finished. I'm afraid it won't actually make it there now. Marc won't answer his phone.

 

Yeah, got into a texting duel with him - he reckons next week. I'm about to go and check the fuses (Occam's Razor)

 

Yeah, still thinking electrical. The coil lead is my next port of call, then the coil itself - anything to delay opening the dizzy (here be dragons).

 

Well, it appears I've been chasing up the wrong tree. I bravely took of the distributor cap, and it was like new inside. So I took it for another run, and it happened again, with a small popping from under the bonnet, which I thought was a misfire. So I pulled over and opened the bonnet, where I noticed the popping noise was a pulse in the LHS fuel circuit. I rigged up a bypass circuit for the circuit breaker, and the car runs perfectly. "Ah, a faulty breaker!", I thought, but after driving it for a few minutes, the bypass wiring started getting... effing hot!! It looks like the circuit breaker was doing its job after all, and a failing pump is the problem. I'll order one when I'm back from hols and see if I can close this bloody thread!