My BX14 RE- Sold.

[Fumbler]

I wince each time you guys say BOOM!

He he he. Got you there!

Replaced the jets. The old carburettor's jets and emulsion tube had bigger diameter bores than the ones originally fitted to the new carb. Wazzed them in and put the thing back on the car. Started it up and it certainly idles better than when the old jets were in it. I've got the sizes noted down so I can look at a handy PDF someone gabve me a while back and see what engine those jets were meant for.

[panky]

I'm down with the kids you know

[Fumbler]

Bloody thing is just as hard to start as it always has been. The original jets have made it run better, though. I'm thoroughly confused- the only two things that haven't been looked at are the fuel pump and ignition timing. The pump is definitely pumping a good quantity of fuel. The initial timing may be off for the new carburettor but I justr have zero clue at this point. I cannot consistently replicate the poor starting- some times it's fine, others its not. It shouldn't be like this.

[white exec]

Have you checked out each item in the ignition system? Can be significantly affected by temperature, if there is a fault.
Haynes has a good section on it, including a helpful schematic.

How good is the spark? Is each plug lead delivering a good fat spark to Gnd (at least 6mm) and consistently?
Are the plug leads good? If they're elderly carbon/fibre suppressor type, renew them.
Are the plugs the correct ones, and new?
PSA ignition modules often go faulty.
Good few measurements/resistance checks listed in Haynes.

Electrical Grounding can be an issue with BX, particularly the petrols, so worth checking the associated Ground points.
Also check out any intermediate connectors, as these can go resistive, too.

[Fumbler]

Distributor cap, rotor, HT leads and ignition module are all new. Coils typically break down in the heat, no idea if they can the other way round. I re-did the main engine earth with a nice fat 32mm^2 cable and we've had no issues there thus far. It's a good old headscratcher, this. It's never been a problem up until I fitted the new carburettor. I have a multimeter so I'll set to checking the components I've not touched against the specs to see if there's anything obviously missing.

I proofmarked the distributor and twiddled it to this position:

16252562837762743304210409233115.thumb.jpg.a2483e08004cf565564f0fff100a39de.jpg

Idle speed increased to an acceptable level as well as being more responsive to throttle. It started well, too, but 1 time out of 4 it does this, so there's no telling as to whether I've done anything good.

[white exec]

Check the spark quality, and also the earthing of the individual ignition components.
You've done the main battery connections and obvious parts, but that might not be the end of the story.
Our son had a 1990 GTi 8v that was plagued with starting (and cutting-out issues), all of which was down to poor multiple grounding arrangements, done with indifferent (and often body-painted) connections.

Also set the ignition timing (dynamically) to the correct figure, rather than by trial-and-error.
Buy a timing light, if you haven't got one - they're not expensive - and use it with a TippEx mark on the flywheel and pointer.
The xenon/neon HT ones can also be used on each plug lead to detect weak or missing sparks.

Forgive me, but it's been decades since I've had to do anything on a car petrol engine, as I gave them up back in the early '90s.

[Fumbler]

Check the spark quality, and also the earthing of the individual ignition components.
You've done the main battery connections and obvious parts, but that might not be the end of the story.
Our son had a 1990 GTi 8v that was plagued with starting (and cutting-out issues), all of which was down to poor multiple grounding arrangements, done with indifferent (and often body-painted) connections.

Also set the ignition timing (dynamically) to the correct figure, rather than by trial-and-error.
Buy a timing light, if you haven't got one - they're not expensive - and use it with a TippEx mark on the flywheel and pointer.
The xenon/neon HT ones can also be used on each plug lead to detect weak or missing sparks.

Forgive me, but it's been decades since I've had to do anything on a car petrol engine, as I gave them up back in the early '90s.

The ignition timing was a last ditch effort. I know this isn't the best situation because I really need a timing light to do it properly, but in my mind there's no harm in trying knowing I can revert it to where it originally was.
I'm in this quasi situation where I've solved one problem but have simultaneously caused another equally annoying one. I replaced the original carburettor because it had no idle circuit and was full of gunk. I have no access to ultrasonic cleaning or anything of the sort so I replaced it with the only affordable replacement that'll fit the manifold. In doing this, the car idles but now won't start easily, if at all. I wonder what's really going on there.

[Fumbler]

Recorded a typical cold start. It begins with around 20 seconds of ranking with no life whatsoever. Then, this happens:


After it's started you can restart it without issue, even if you let the float bowl run dry and re-plumb it in. It re-starts with no problems at all. Is this electrical?

[panky]

That's very typical of an air leak, exactly how my Camper acted before I sorted the leak. But since you've discounted that I'm a but stumped, are there any open ports anywhere on the carb body or manifold?
Try a dribble of fuel down the carb throat, about an egg cup full, if it starts straight away then it's a fuel/air mixture issue.

[Fumbler]

That's very typical of an air leak, exactly how my Camper acted before I sorted the leak. But since you've discounted that I'm a but stumped, are there any open ports anywhere on the carb body or manifold?
Try a dribble of fuel down the carb throat, about an egg cup full, if it starts straight away then it's a fuel/air mixture issue.

It certainly looks like I'm chasing an air leak now. I've tightened up the top of the carb so it's now sealing. I wonder if I haven't tightened it down onto the manifold enough. I definitely didn't want to overtighten things, but I may have left it too slack.

[panky]

It's possible you haven't tightened it down evenly or possibly an piece old gasket stuck on one of the surfaces, only one way to find out

[Fumbler]

Indeed, the gasket was clean and had no rips. The mating surface oin the carb was clean too. Off I go to twiddle some bolts. I might as well revert the timing as well given that wasn't the issue.

[Fumbler]

...Tightening up the carb did help, there was a slight leak at the back. Whether it's helped with starting, I don't know.

[rutter123]

What about the inlet manifold gasket where it seats on the head or the vacuum pipe, if u have leaks here starting will be an issue.
I had a Dyane years ago which was always a pig to start regardless of hot or cold, even after changing g everything leads, plugs, coil, caps, pump, gaskets, points, condenser, etc it was only marginally better, it would always start just needed a lot of cranking.

[Fumbler]

I rectified a vacuum leak at the manifold.carb gasket and I rectified the leak on the emission control system.
Starting is definitely better, but it's done this before. To clear is throat a bit, I gave it a spirited drive to the petrol station. Started up fine at the forecourt and off again I went. Putting the original jets in has improved the torque somewhat, so I'm happy with that. I think at this point it's just seeing if it starts better tomorrow morning, and whether I can trace any other vacuum leaks. There are only two vacuum hoses- the vac advance on the distributor looks ok and is pliable, the emissions vacuum pipe was perished so I replaced it, I sealed up a union on that pipe system and I tightened down the carburettor. There aren't many other places air can enter when it shouldn't.