Morris Minor Owners Club

hi guys i know its not a moggie but,its still a A series engine,today the car was running perfect,then i parked it up and went to have dinner,i came back to the car about 1 hour later and it wouldnt start,i kept cranking the engine over and it finally started,its firing on 3 and back firing,i just changed all the spark plugs.any ideas? please

thanks
john

Back firing is too much unburnt fuel isn't it.. I guess it's not a fuel problem but a spark problem on one cylinder. Check to find which one isn't firing start with the plug swap them (could be dodgy plug), then work back through the leads (swap one around and see if it still isn't firing), check dizzy cap.

ive changed all the spark plugs and leads and they are working and getting spark, im confused :S

Is it a strong spark? Does it spark every time it is suppose to? The reason I ask is for it to back fire there must be ignition in the cylinder eventually. Maybe not everytime or weak... are the leads firmly connected and getting a good connection into the top of the dizzy?

No-one jokingly has swapped the leads around have they while it was parked up?

yeah i checked all the leads and replaced them.im going away on holiday on saturday so i gotta get it running before then otherwise no holiday

How was it running before the leads and plugs were replaced...?

i replaced the plugs and leads after it started playing up.it was running perfect earlyer,then it suddenly started playing up.

An A-series in a Robin? Are you sure? They normally have Reliants own little engine that runs very well. They go like a bullet when set up nice. As the others have said, go through everything again, plugs, points, condenser etc. My old Robin used to suffer from fuel vaporisation on a hot day, those engines do get hot in that little bay. It does seem odd that it was running well then suddenly gave trouble.

sounds like the condenser as packed in to me

Stuck open valve ? Check the valve gaps - and do a compression test. As earlier - never heard of an A series in a Robin! Doesn't mean we won't help - but are you sure it's an A series ??

748 OHV light alloy according to the Reliant site

Check the points gap hasnt closed up. Or try a different coil they can fail if you,ve left the ignition on for a long while recently without having the engine running.

If the distributor cap is damaged it can divert the spark to the wrong cylinder, hence the backfire. It took me ages to track that fault. I couldn't work out why the engine speeded up when I removed an HT lead.

My first venture in to motor mechanic was nearly 40 years ago. I changed the plugs and leads on my Reliant and it wouldn't start afterwards!!

I'd put the leads back the wrong way round - it mis fired and wouldn't run. Funny, I've never forgotten the embarrassment of making a simple mistake.

thanks for all your help guys,i found the problem 2 of my tapets have come lose,but the threads have gone,i tightened them and it ran fine for about 30 seconds and started playing up again,and found out they had come lose again,so will need to re thread them.

thanks again
John

I'm not so sure that you will find that the tappets are the problem, they would have to be a very long way out to cause the problem you described.

Did you do anything else to the engine??

And you haven't confirmed whether it is definately an A series engine?

Moved to off topic - Roger