Running problem that feels like fuel sarvation

[guystrungout]

Hi,
I have a very frustrating problem and I can't seem to get to the bottom of it.
I'm running a standard 1098 engine and carb with electronic igniton, which has been on for about 18 months.
Since Christmas and for no apparent reason my car has been coughing and spluttering on every journey over about 5 milles, in other words, after she has warmed up. I say coughing and spluttering but in reality it feels like fuel starvation, but I don't know how else to describe it, but its as if there's not getting enough fuel through at key times.
Its as if something is occassionally blocking the the carb or fuel line and it seems to happen most dramatically on hills and when the throttle is needed in a situation like over taking, in other words when she needs more fuel.
She also conks out when I have to stop at junctions or in traffic, which is very frustrating, but other times she will be fine. She will always start again but not always straight away, sometimes it will take a few minutes until she starts again, which must be really annoying for anyone stuck behind me!
At these times I am usually under the bonnet checking that fuel is getting to the carb and that all the right wires are still attached to the relevant places. I have never found anything obviously amiss in these circumstances.
The symptoms are aslo similar to a failing condenser, of which I have had too many in recent years which is why I fitted electronic ignition. She will sometimes backfire too and cough and splutter when I'm on a straight and level bit of road but never conks out on the flat in this situation, only on hills and at junctions.
It's making driving anywhere quite stressful as I never know if she will conk out in traffic or whether I will make it up any hills without it conking out halfway up.
As far as trying to sort it out goes, so far I have checked the filter on the fuel pump which was a bit mucky, I have cleaned the float chamber and replaced the needle and seat on the carb. The fuel pump seems to be working fine and has had new points, a few years back now.
I have also replaced the coil with a new one because I have had similar experiences with those over the years, breaking down slowly, sometimes running fine for ages and then playing up randomly, and when left for a while would start working again.
The spark plugs and filters are about 4000 miles on from the last service and I am running out of ideas.
My next idea was to drain the tank and see if there is anything floating about in there, but I'm pretty sure I won't find anything. I was also going to replace the carb with a spare I have knocking about and see if that makes any difference. I've also checked the fuel cap to make sure its not causing a vacuum.
Could it be the electronic ignition? As there are no longer any points or a condenser to change I am at a loss as to how to check it is working correctly. Its made by Acuspark by the way.
Can anyone out there give me any ideas please? I have had Moggys for 30 odd years and I do all my own mechanics but I have never had a problem like this that I haven't been able to sort out and I'm really baffled and starting to get desperate! Help!

[firehor5e]

I had a faulty acuspark elctronic dizzy,the engine would run well whilst stationary,could give it plenty of revs no probs,would run ok while just driving slowly,but try to go up hill or accelerate the car would miss fire,back fire judder etc.I messed about for weeks,fuel pump,carb,manifold gaskets,plugs,leads etc etc.Put the old dizzy back on....sweet. I have since fitted another acuspark electronic dizzy and all ok.Hope this helps and good luck.

[amgrave]

Next time you are out and the car plays up try pulling the choke on progressively and see if it runs better. If it does it is a sign that the problem is a fuel related one. If not it's more likely to be spark related. Check all the connections you can find to do with ignition and make sure they are tight and clean. The problem could even be coming from a dodgy ignition switch so you will have to work through all the items to find it, it could literally be anything.

[kennatt]

have you tried checking the mixture via the lift pin when at running temp, sounds like a fuel mix problem to me.

[guystrungout]

Thanks for the advice, much appreciated.
Yes, checked the mixture early on. Tried all the simplest things first.
I could do as suggested and swap the old dizzy for the electronic one and then at least that would rule that out for definite. As you say it could be literally anything! But ticking things off and getting there slowly.
Will keep you updated on progress. Cheers.

[mogbob]

I'm thinking more fuel flow than electrical.

Going from tank to engine. Crud in the tank or main line to carb is a possibility ( leave to last , if simple fixes don't work / have been eliminated ). Rubber pipe ... pump to carb... condition ? Was there specs / flecks of black in the crud you cleaned out of the float bowl ?
If you haven't got a modern " unleaded resistant " pipe then unleaded fuel attacks original rubber. It perishes , causing the pipe to collapse under pressure ( engine calling for more fuel ) restricting fuel , leading to loss of power on the hills. Black flecks in the float bowl = disintegrating pipe.
Piston did you extract and clean this , when you did the float bowl ? Needle condition good , not bent , no ridge on contact area , secured firmly in the piston , falls sharply to the bridge when the lift pin is operated ? Oil in the damper ?

Air filter ...clean , not clogged up. If dirty , it would provide marginal supply of clean air at idle , struggling when under way , requiring more power.

Cables accelerator and choke , smooth operation throughout the range, no kinks , frayed cable , obstructions , lubricated.

Nuts tight on carb body to manifold and manifold to engine ...no air being sucked in , where it shouldn't.
Good hunting.
Bob

[myoldjalopy]

If a car starts playing up without you having fiddled/replaced anything, its often a component failure - and it would appear not to be anything you have since replaced. So, in this case, I would suspect the electonic dizzy. However, Bob's suggestions of checking the fuel delivery system would be a quick first on my list, to which I would add see if the pump is pumping properly with the pipe removed from the carb float - I think people say a pint in two minutes is optimum. And, yes, beware fire risks here! If there is an in-line fuel filter between the pump and the carb, then that has been known to cause problems. You can try blowing down the fuel line back to the tank in case of a partial blockage in the pipe.

Check all HT and cable connections in the ignition system.

If all those checks don't find the solution, fit your old dizzy (good points, set up correctly etc. and a good condensor from Distibutor Doc ) and see if she goes then.............

[guystrungout]

Hello again and thank you all for your suggestions and ideas they have been very helpful.
Judging from the first posting I have a sneaking suspicion that it may well be the electronic ignition so I will do as suggested and swap the dizzy back to the original before I start draining the tank and all that palava.
Funnily enough I have been wondering if it might be that because if it was fuel starvation why would it randomly backfire? Surely a backfire is an accumulation of unburnt fuel that suddenly gets ignited, and if that's the case then it means the spark must have failed to allow that to happen? Which has happened to me in the past when the condenser has started to break down too. Or do backfires happen for other reasons too and I'm way off the mark?
You don't have to answer that it was just a random thought I had today!
Anyway, I will do that first and if it turns out to make no difference then I will still have to go through all the other options too but at least I will know for sure.
Oh and just so you know, the fuel pipe from the pump to the carb is a nice shiney new braided one that has been on for about 12 months so its not that falling apart internally. And the muck in the pump filter was mostly tiny rust flakes and tiny bits of black grit that didn't amount to more than a little finger nails worth. The sort of thing I would expect to find in the fuel tank of a car this old anyway!
Thanks again, I'll let you now how I get on.

[guystrungout]

Hello again,
well this morning I swapped the electronic dizzy for the old 'trusty' points and condenser version again and lo and behold the problem seems to have cleared up. I took her for a run that included several hills, one very steep and no problems so far.
So I will now email Acuspark and see if they can offer me any advice.
One other problem this has highlighted though, which I wasn't aware of until today, was when I took the Acuspark dizzy off the advance and retard unit had petrol in it. How on earth can that be happening? I thought the advance retard was activated by the vacuum caused by the carb drawing air so how petrol has managed to migrate back the other way has got me baffled .
Any ideas on that one anyone?
Thank you all again for helping me on this one, its been quite an interesting(and frustrating!) problem, especially as it felt so much like fuel starvation.
It just goes to show that things aren't always quite what they seem sometimes, and if in doubt ask the forum. Don't suffer in silence.

[myoldjalopy]

Great! Glad to hear its sorted. These electronic gadgets are not infallable. If you stay with the old dizzy, fit a RED rotor arm and good points AND condensor from the Distributor Doc - and service the dizzy as required. I have had sudden failure on the road previously due to poor quality rotors, but not with the red one fitted. And setting the points is quite a satisfying job, especially when car goes noticeably better afterwards!
But I can't explain petrol in the vacume!

[amgrave]

Have you still got the bulb fitted in line on the vac tube? It's purpose is to stop any fuel getting as far as the vac bellows and should be fitted carb side down.

[firehor5e]

Glad you are all sorted now.I even replaced my twin carbs for a HIF44 while i was going through the same problems as you.The fuel in the vac is prob due to the backfires (caused by the dizzy)forcing fuel down the advance/retard pipe.Now the Moggie is running well this should not happen again.The early vac system(the metal pipe type)had a non return valve fitted i believe

[guystrungout]

Excellent, thanks for your responses to the fuel in the vac unit issue. I have a 'modern' black plastic vac tube so no longer have the non return unit fitted to the old metal tube. I always wondered what that bit was for, so thanks for enlightening me on that one.
And I'm glad to hear I'm not the only one who has suffered in a similar way. I only hope that all this will be helpful to others who may have a similar situation and read it in the future.
Best of luck to everyone.

[David W.]

I put accuspark components into my dizzy. It ran great for about 15 miles. Then it ran no more. I had to be towed home. I put the points back in and haven't had a problem.

[myoldjalopy]

The old ways are the best ways!

[guystrungout]

Indeed, and as some wise old sage said, probably on this thread in fact, at least you can replace the points and condenser at the side of the road if you are sensible enough to carry spare ones, (which I have also done numerous times) whereas what do you do when the electronic ignition fails? Apart from replace the whole distributor with the original one, which funnily enough I have just had to do. Was hoping to avoid all that in the future by 'up grading' to electronic ignition, ho hum....someone else also said 'the road to hell is paved with good intentions!'
Forward into the past!