Quote: "Another cause, may be something to do with the idle jet on the car getting stuck/blocked. im not too clued up on this, but alexGS - he's your man to ask "
You're very kind, luke!
Actually I was reluctant to offer quick advice because I didn't feel certain about the cause. It's really a case of working through things in order. Plus, I'm not clear: does the engine ever idle correctly? Is this just a transitional or occasional problem, or all the time? (e.g. if 'transitional' problem, and goes away when engine is fully warm, idle speed is probably set too low!)
OK, so a few things:
- You haven't mentioned if the choke makes any difference? That would surely be the first thing - just pull that a little to stop the engine stalling (the first 'click' only increases the speed, it does not put more petrol into the mix). So I'm guessing that you don't have a choke - which makes me think it must be fuel-injected (SPi). I don't know much about those, Monty Mort is the choice there
Assuming a carburettor, we continue...
-If there is a choke, but it makes no difference, I think Luke's onto a winner. Unfortunately, finding the idle jet varies between different carburettors, so I can't tell you where to find it. Usually, you take off the air cleaner, and there are several brass 'screws' visible in the top of the carburettor - they are the jets. They are delicate things - even the hole in the top is important - so use a nice big screwdriver and be careful. But the garage should have eliminated this problem for you and they should have blown out the carburettor with compressed air to remove any dirt, etc.
- Fuel cutoff solenoid. Not sure if your Uno has this, but if it does, and the connection's broken, the engine won't idle. The cutoff solenoid is screwed into the carburettor near the bottom, with a single wire (usually red) hanging out of it. Check, with a multimeter, that this wire gets 12V when the engine is supposed to be idling. If not, wire it permanently to the red/orange wires on the ignition coil.
- Vacuum advance/air leaks. Air leaks can lean out the mixture and should be stopped-up as already described - but note below:
- Ignition timing. The vacuum advance on a FIRE advances the ignition timing even when the engine is idling. Advanced timing = higher engine speed. So it follows that without the correct advance, the engine may stall. So, you could replace the vacuum advance unit, or possibly just turn the distributor body a little (slacken 2x 10mm nuts first) to see if you hear the engine speed increase. If you do, then it's probably worth getting someone's help to set the timing properly (otherwise, just return it to the marks you made - you did remember to mark the position before disturbing the distributor, didn't you?
)
Idle speed screw - well this is so simple I almost didn't bother mentioning it! but just in case... There's a slothead screw with a spring under it, that bears on the throttle cam (carburettor, where accelerator cable attaches). Turn it clockwise ('do it up') to increase engine idle speed.
You see, I can't figure out what circumstances the problem occurs under. When you say 'engine is warm', do you mean 'after you push the choke in'? I am getting the impression that by 'blipping' the accelerator you can keep the engine going, is this correct? If so, I think it's most likely to be a blocked idle jet or the fuel-cutoff solenoid. If you only have to hold the accelerator slightly down, then it's the ignition timing/vacuum advance, or the idle speed setting. Just my guesses of course, no great guarantees!
On the other hand, if the engine dies altogether no-matter-what, maybe it is the ignition module on the distributor (overheating, etc.) in which case you need to try a replacement for it. It's quite easy to swap with the distributor remaining on the engine.
But, as you can tell, I'm clutching at straws because I can't get a good mental image of the problem.
It is quite possible that it was a blocked jet, and it has merely blocked again because the carburettor wasn't cleaned properly or the fuel filter wasn't replaced. I find, with blocked jets, you have to do a thorough job to prevent it happening again! So, keep going back to that garage you paid, until they can absolutely assure you that it's not that at fault - in which case, they shouldn't have charged you the money...
By the way, sorry if this post is offensively 'basic' to you, I'm just trying to start from the beginning rather than jumping to any conclusions!
Good luck!
-Alex
