Morris Minor Owners Club

I’m 3 days into a job that should have taken 10 minutes

Backstory - Nellie has been running decently but not perfect, noticed the carb was looking a bit grimy and there was a bit of a petrol seep from the float bowl. So under supervision I removed the carb a few days back, dismantled and cleaned it, reassembled. Noticed the gasket at the top of the float bowl was in two pieces so that was replaced, thought that may have been the cause of the leak.

Two days in, Nellie is running well… but still noticing seepage from the float bowl and with the carb cleaned up I could identify exactly where the leak was coming from - basically the seal where the jet tube enters the float bowl. Long story short a quick ‘I’ll just check/replace the rubber washer in the tube’ turned into having to replace the jet assembly, the jet tube and the float bowl (luckily I had a spare carb pretty much identical to mine that I took the bits off).

The leak is resolved, but Nellie is not running at all well. Initially she was cutting out while on the move (something she’s never done with me) and further adjustments seem to be making the issue worse, yesterday after adjusting the mixture again I fired her up and the engine was absolutely racing. Managed to adjust the idle screw (I think that’s what it’s called?) and got the idle back down to normal - didn’t drive her at that point as it was getting on for rush hour, plan was to test drive this morning when roads were quieter. But on start up this morning engine is absolutely racing again… something is not right??

Clearly replacing the parts has caused some sort of upset and I’m at a point when I think I should really get a professional in, because right now I feel like I’m causing more problems then I’m solving. The only thing I haven’t done is replace the gasket between the manifold and the carb, I’ll be doing that tomorrow, but my thoughts are, if she still isn’t right I should call an expert.

Just wondered what your thoughts were on this? Am I missing something really obvious here?

Advice is most welcome!

Maybe the jet underneath is not centralised, allowing the needle not to seat fully ?

Ok so you replaced the jet (which has the tube to float bowl as part of it) and the whole float bowl with lid and float or just the bowl?

A couple of things come to mind. Maybe the needle got bent when the jet was replaced and the carburettor piston is sticking. To test this, take the air filter off, look inside the hole where the air filter was and identify the piston. Lift this with your finger, let go and check the piston comes back down briskly and with a "metallic clunk". If it sticks, the needle is bent. If you disturbed the jet centring nut (which you do not have to disturb to change a jet) then sticking shows the jet is not centred. The mixture nut is the lower nut, the jet centring nut (normally never touched) is the upper nut.

If you replaced the float bowl complete with lid and float possibly the float adjustment is incorrect and the fuel level in the float bowl is wrong. You know it was OK before so just put the old lid with float attached back on.

Stephen

Thanks for the replies, I changed the whole float bowl and the lid and the reason for this was because when I tried to screw in the nut to attach the new jet tube it wouldn’t go, and looking at the hole, it appears the threads are a bit buggered.
Somebody had previously replaced the regular tube with a black rubber one with a plastic end and sort of shoved that in there… but of course there was no real seal so it has been steadily seeping out.

The needle wasn’t bent and doesn’t appear to be sticking but I agree the issue definitely stems from me changing out the jet assembly etc

Honestly right now I wish I’d left it alone, but I just didn’t like to ignore a petrol leak, even though it was small

You had a go, that’s a good attitude. A lot of jobs on a Minor can be reasonably straightforward and when they go well, you’ve saved some money.

I’m just disappointed because I really wanted to learn to take care of things myself. But with this job I’m kind of at a stage where I don’t actually know what to fix or how to fix it… and I don’t want to just keep ‘tinkering’ and hoping for the best.
Having your car cut out on you multiple times in busy traffic is absolutely not fun, I know it’s part of the learning curve but still… I have a lot to learn!