Morris Minor Owners Club

At high speeds (over 45 MPH), my engine has developed a slight 'cough' or misfire every couple of seconds which sends a slight vibration through the car. I know of 2 jobs which need doing (exhaust manifold to downpipe needs sealing properly and HT leads look a bit past it), but am unsure if this is the cause.

The dist. cap, condensor, points and plugs were renewed not long ago.

Any ideas?

this happened to me coming down the M6 in the outside lane.

i pulled over and stopped. the car would start and tick over, but when i pulled away, the same happened.

i changed the fuel filter and it cured it.

failing that, it is electrical. you can rule out mechanical.

OK, thanks. Deffo not fuel problem as there is one of those glass filter things fitted, and it's flowing freely.

Reading about dodgy condensors makes me think... as do the HT leads.

Is the glass filter thing on the dashboard so you can see it at speed?
Try looking at the running engine in the dark to see if sparks are going astray.

make sure the leads aren't touching some bare metal as well.

Just get rid of any filter - not necessary...... What colour are the spark plugs? May be dangerously weak........

bmcecosse wrote:Just get rid of any filter - not necessary...... What colour are the spark plugs? May be dangerously weak........

Last time I checked they were a grey-white and yes, the mixture was noticably weak then. But I adjusted the jet and it ran better with more power.... but not checked the plug colour since.

It's either loose connections - or struggling for fuel supply at high demand.

Turns out it was running too weak as I richened it and have had no trouble since. Will check plugs after its done a few miles like this.

May be best to err on the side of rich.