Misfiring!

[Hillclimb1]

My 1098 morris minor 1000 has developed a misfire, I don't use it as a daily but when I take 'Ernie' for a drive he seems fine, starts up first time on cold mornings, after about 40ish miles of driving begins to pop and bang out the exhaust before jerking and becomes undriveable loosing power. Weird thing is after pulling over for around 30 seconds it will go back to normal, rev fine and drive for another mile or so before repeating.
Within 2 months ive replaced the ht leads, coil, rotor arm/points/condersor.
There's no loose connections and fuel pump is working fine, spark plugs aren't worn, any ideas?

[moggiethouable]

Is the fuel pump new?
I had one that failed after 9 miles running, then when cool a hot component cooled and it worked fine for another 9 miles.
I sent it back for repair, hey presto sorted.
Also I had a stalling problem that I nailed down to a split vac advance pipe.
In both cases there was no misfire though, just a dead stop with the first and a chugging and loss of power with the second.

[morris van]

I replaced the engine and dizzy in my MG Midget six months ago and 3 weeks ago it started misfiring I replaced fuel pump, leads etc and I took it to a garage and mine was a faulty new condensor.

[mike.perry]

Things to check
Plug gaps and tight
HT Leads Secure
Distributor Cap not cracked
Carbon brush in cap springs in and out
Points gap
Condensor
Insulators on points in correct positions
Small wire in dist. in good condition and not shorting
Dirt in float chamber bowl
Collapsing flexible fuel hose
Fuel cap vent not blocked
Probably a few others

[bmcecosse]

Sounds like vacuum in the fuel tank. Put the old coil back on - it's NEVER the coil...

[Jaywhy]

I had a similar problem last year changed everything ignition only for it to return time after time. In the end removed condenser and points and fitted electric ignition and never had problem since. I have put it down to poor quality points and condensers.

[liammonty]

Vacuum in the tank will be easy enough to check for - just loosen the cap and see if it still happens.

You've done the right thing changing the ignition components, as it quite likely is that. Trouble is, the new parts available are often far worse quality than the ones being replaced. Don't assume that just because you replaced them, you've eliminated them as being the problem. If the problem persists, get new points, condenser and so on from the 'Distributor Doctor' who manufactures his own decent quality parts. I've used them on several cars and have never been disappointed. Regarding the coil, I'm afraid it very often IS the coil these days, as the original reliable ones are upwards of 50 years old, and the new ones available are generally utter junk. It may be worth changing it for a known good one if the problems don't go away. I've had coil failures on 2 Minors and my Landcrab, and the symptoms were exactly what you are experiencing.

[ManyMinors]

I can only agree with what Liam (above) has said. As for the "never the coil" comment I'd take no notice of that. My Minor saloon developed very similar symptoms earlier this year - would always start from cold and run perfectly for the first 6 or 7 miles and then run less and less well until it would backfire, misfire and finally cut-out altogether and not re-start for some time. Going through the car one thing at a time the problem was the coil, now replaced and running as well as ever again.

It's never the coil..........until it IS

[bmcecosse]

Not if it's a good old coil! Modern coils are a complete shot in the dark.... It's a device that either works or doesn't work - it can't ' fade away' after a few miles... It can perhaps have bad/corroded connections to the terminals which maybe heat up and develop increased resistance... Well worth checking the connections.

[dalebrignall]

reliable modern coil accuspark sports coil the red one

[Hillclimb1]

Thanks for the replies chaps, I assumed it wasn't the coil but swapped it anyhow just in case.. was from an Austin a40 as we have a couple of a40s, but from what I've seen and read up, ill probably buy an electronic ignition, everything else seems tip top!

[Sandun]

Yes it NEVER the Coil -change old coil back - That u said u change All parts of Distributer, - check ur rotor arm if it bad burn ,problem of rotor arm ? Check ur points if it bad burn problem of condenser - if come bad fireing sound, problem of ur coil - i am sure problem is ur rotor arm - and rechange condenser too now, - the problem like this , some thing short in ur distributer then it hot ur coil and fail it work then misfire the coil , after that when the coil cool back ,it work again but can not run far more 4km till u found the electric short - Good Luck

[The Issigonis Kid]

OK, so you agree its unlikely to be the coil, you've consider installing an electronic ignition but what did you do to fix your stalling problem - did BMC's advice about the Vacuum Advance Pipe help - I was reading the thread looking forward to finding out what this is, where it is, how to replace it and whether it fixed your problem. Does your car still misfire, if not what did you change to fix it. Mine only misfires (and dies) when hot. Thanks

[Hillclimb1]

Hello there, I will p.m you