Engine Dying (Petrol)

2 ¼ Petrol Series III. I took it out and after about 5 miles it started popping and banging, back firing through both the exhaust and carb, and no power. Managed to get it home (about 8 15 on a Sunday morning, I doubt I was popular)
Decided the symptoms fitted failed condenser, so changed that. I eventually coaxed it into life on one cylinder.
Reset the points, (I thought I’d managed not to disturb them, but I obviously had) and took it for a spin round the block, pulled like a train.
Took it out for a longer run today and after a couple of miles started to missfire again, but without the popping and banging, until it eventually died. Did a bit of fiddling with points etc, and eventually it restarted, however it appears it was just a waiting of waiting, anything between 30 secs and a couple of minutes, and it would restart and run for another 10 yards to ½ mile.
I’m pretty sure my initial diagnoses was correct as this is a subtly different problem,
Initially it would pop and bang but kept going, though with little power, now it just starts missing and dies if the speed drops, and then struggles to restart

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Davec said:

2 ¼ Petrol Series III. I took it out and after about 5 miles it started popping and banging, back firing through both the exhaust and carb, and no power. Managed to get it home (about 8 15 on a Sunday morning, I doubt I was popular)
Decided the symptoms fitted failed condenser, so changed that. I eventually coaxed it into life on one cylinder.
Reset the points, (I thought I’d managed not to disturb them, but I obviously had) and took it for a spin round the block, pulled like a train.
Took it out for a longer run today and after a couple of miles started to missfire again, but without the popping and banging, until it eventually died. Did a bit of fiddling with points etc, and eventually it restarted, however it appears it was just a waiting of waiting, anything between 30 secs and a couple of minutes, and it would restart and run for another 10 yards to ½ mile.
I’m pretty sure my initial diagnoses was correct as this is a subtly different problem,
Initially it would pop and bang but kept going, though with little power, now it just starts missing and dies if the speed drops, and then struggles to restart

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Look for cracks in the cap or around the top of the coil, pull all the leads out and make sure the contacts in the cap and coil aint corroded. Good time to try it when its dark and see if you can hear or see where it's tracking across from.

I had a similar problem with my 109. I replaced the coil,points, condenser, dissy cap, plugs and leads. The problem persisted intermitently. Eventually I replaced the fuel pump and now the motor pulls like a train, again.

Thanks for the prompt advice. Within the last year it has had:
New fuel pump
New Coil,
New distributor, including new leads.

I know that doesn't necessarily mean they are not the problem, but you can see why I am getting frustrated.

I had a Transit Minibus doing the same sort of thing. Turned out to be a faulty coil. It was only about 2 months old,( the coil, not the bus). Took it back to supplier who gave me a new one. Fitted it and 't job's a good 'un.

Always nice when you get the answer you want, I've got a coil on order (although it was new last year it was old stock and had been on the shelf for years until found during a stock check)
I'm still open to other suggestion though, if anyone has any ideas

yep sounds like the coil to me too.

General Wallace said:

I had a similar problem with my 109. I replaced the coil,points, condenser, dissy cap, plugs and leads. The problem persisted intermitently. Eventually I replaced the fuel pump and now the motor pulls like a train, again.

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Took me about 10 years to get round to replacing the fuel pump last year, it did cure lots of niggling little annoyances I'd been living with for years.

The description is a classic fuel supply failure.
As the fuel supply fails to keep up with the demand the fuel level in the carb drops and the mixture goes very LEAN, and the popping and banging results from that. It is bad for the engine and risks setting the carb on fire.

Chase the fuel supply system all the way through from the tank, because fiddling around might just cause you a lot of grief.

I think it less than likely it's ignition, and you do yourself down too much!

CharlesY

Thanks CharlesY, I had problems with the fuel pump last summer, and the symptoms, although sounding similar on paper, were subtlety different. I hadn't thought about something floating round in the tank blocking the pick up, or water in the fuel, but I did look at the glass bowl on the pump, and that was full, so I don't think I'll put fuel to the top of the list yet. I won't discount it though.

You may also wish to keep CARB ICING up inside at the venturi very much in mind.
This is just the weather for it. Cold and damp.

All petrol engines should draw their inlet air over the hot exhaust manifold.

But as you tell it, the problem happens so soon I fear icing would not have time to form.

Fuel flow problems ... put a TEE-PIECE in the fuel line just before the carb and put a hose on it leading to a gallon can.

If the fuel supply (lift pump etc) is in good nick the engine will run fine on a fast tickover and it will pump half a gallon of petrol into the can in under a minute.

Well, it would if all was well.

CharlesY

Lot of experience of icing over the years, it's often me who suggests it, although it hadn'y crossed mt mind this time. Shows the value of gettingothers to think about you problems, but pretty sure that's not it on this occasion.

Davec said:

Lot of experience of icing over the years, it's often me who suggests it, although it hadn'y crossed mt mind this time. Shows the value of gettingothers to think about you problems, but pretty sure that's not it on this occasion.

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I share your view ..... but ...... !

Do the fuel supply check and after that the carb itself (but what?) and then it looks like the black art of coil ignition.

I have experienced a coil that broke a winding wire. When it was cold the broken ends met up and it worked. As soon as it warmed up the ends moved apart and that was that. But it always took 4 to 5 minutes to do it.

Yours sounds as if it gets a float-chamber of fuel at the start but not nearly enough coming in after that.

CharlesY

Unfortunately as it is dark by the time I get home I won't get a chance to do anything until Saturday, but I've certainly got some ideas!

What carb is fitted? if it's a Weber, then check the fuel inline filter at the carb, this will cause similar symptoms.

JMCT said:

What carb is fitted? if it's a Weber, then check the fuel inline filter at the carb, this will cause similar symptoms.

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You bet!

ALWAYS check if a carb has a last ditch brass gauze filter, and sometimes they hide them inside banjo unions.

CharlesY

Just to close the thread off, most things replaced and now going fine. The last problem I had stating was the choke flap jamming. Never come across that before, but someone else reported it on LZ the same week!
Thanks for all the advise.
Now all I have to do is change the front diff!

Never assume that because you bought a new part that its a good new part !!! there's a lot of after market crap out there (brakes are the worse and springs come a close second in my book) check it all again, make sure the part is 100% before you re fit it, it sounds to me like you have the problem, but the part has let you down