10 replies to this topic

[roverlander]

I have a 1275 mini which is running on a 45 weber carburettor and electronic ignition. It has just started to go down to firing on cylinders 2 and 3. I have checked leads, plugs, cap, valve gaps, timing. If I clean the plugs then it will fire up on four cylinders but only run for a short while before dropping down to 2 and 3 again. The plugs look OK when they are removed and if I put the plugs from the faulty cylinders into the good ones they run ok and likewise if I put the good plugs into the faulty cylinders they do not fire. If I pull the leads of the non firing cylinders and hold them close to the top of the plugs they seem to have a good spark. The car will tick over quiet well on only two cylinders. If it is a fuelling fault I do not understand why one cylinder being fed by one barrel of the carb is firing and the other cylinder does not fire. I have good compression in all four cylinders. Any Ideas please.

[nicklouse]

leads on in the correct order?

[nicklouse]

webers often over fuel on the two outer cylinders so may be have a set up session.

[roverlander]

Yes. I can remove 1 and 4 with no difference to it ticking over or running. If I pull either of the other two it cuts out. If I try lead 1 on cylinder 4 it backfires and the same happens if I put lead 4 on cylinder 1.

[roverlander]

It does not seem to smell of fuel at all. When I pull the two non firing plugs out they seem pretty dry considering they are not firing but do not understand why no fuel when inner two cylinders appear to be working fine.

[Dusky]

Show some pics of the plugs.
What plugs are you using?
If it gets worse when braking you should check the choke barrels.

[roverlander]

plugs are BP9ES. I have tried altering jets and richening mixture up to see if it will fire up but still nothing on 1 and 4 cylinders. Plugs look really clean but very dry on outer two cylinders. Thinking maybe take the head off just to have a look but symptoms don't suggest there would be anything wrong.

[midridge2]

Have you done a compression check to see what 1 and 4 read.

[Dusky]

Bp9 is way way too cold. Try bp6.

[Cooperman]

Yes, try a BP6ES or BP7ES.

 

Increase the tick-over speed to between 1000 and 1100 rpm

[gazza82]

Yes. I can remove 1 and 4 with no difference to it ticking over or running.

We had an MG Midget that did that ... burnt out valves on two cylinders!