Where should I be looking chaps, I'm thinking the carb but losing the will to live with it. She fires up and idles beautifully from cold, runs and drives great or as well as a 2 ton brick with 50hp should. If I stop and switch the motor off for more than a minute or so though on restart she dies rather than idle. If I keep the revs going on the throttle and keep driving after 10 mins or so she stops refusing to idle and purrs away again at the lights? The electric choke appears at least to be correctly adjusted...... Thoughts ?
Is your stop on the cam set up right ,once hot you need to be a fag paper away on bottom step , have you adjusted carb /screws byepass etc when engine is warm.
if it corrects itself quite quickly it might be the fuel has evaporated from the carb and causing a short time of fuel starvation........
Have been through this a number of times.........haven't checked the stop hot though..... will give it a go!
It's not so quick, it can be a few miles of driving before it catches itself and idles pulling up at a junction etc
Power failure on idle shutoff solenoid or sticky ? When the engine is cold the choke holds the throttle open , and the choke flap increases the suction, fuel comes into the engine and it will idle. Once it has warmed up, the choke snaps off and the idle fuel now comes from the little idle circuit . If the solenoid is not working, there is no fuel. The other possibility is a vacuum leak. Again the choke initially holds the mixture rich even with the air leak, but then as it warms up the choke snaps off and the air leak takes over allowing the mixture to go very lean and idle dies. Once you know you have an air leak , it is possible to recognise the harsh hissing sound of air rushing into the leak - a carburettor hisses but it is muted by the metal. Try waggling the throttle spindle from front to back . You may well be greeted by a varying hiss from worn bushes on the steel on die-cast cruddy bearings in a stock carburettor.. Once the engine cools down enough for the choke to reset , it will idle.
It's kind of the opposite. It idles consistently after about 3 miles of driving following a hot start. Or idles perfectly from cold, and runs fine no issues and continues to do so until switched off for a few minutes...... then we are back to stalling at lights for 3 miles or so. I've kind of convinced myself it's something to do with the bi-metallic choke...... but it seems to operate to spec when tested?!? I rebuilt the solex in the summer and replaced the bushes with phosphor bronze ones. If its an air leak it would seem to be very temperature dependent......I.e no leak cold, no leak full operating temp.....but leak somewhere in between....
Had this on mine. Changed the empi exhaust ( which got rid of air leaks) to a standard exhaust and bingo tick over! Basically,it was air leaks causing the problem.
This could be a fair shout...... I fitted a new exhaust in the spring and I'm not fully happy with that seal achieved on the passenger side the quality of the part was poor the ports didn't line up properly and there was a lot of tension getting it all bolted in place, can't see any carbon but can hear a bit of chuffing when driving past buildings / walls etc..... will investigate over winter.
Had almost the same issue but this when I was setting up the carb from scratch in my garage. in the end it was the original brake servo leaking air. So when the choke came off when hot the engine stalled. A new servo did the trick.
The confusion for me is that it runs when fully hot and idles fine, runs when fully cold and continues to run straight through to fully warm. However will not idle on a warm start..... which suggests to me choke related as it's a simple bimetallic strip that will have wound on with a lack of voltage during the stopped period.... however this would make the mixture richer not weaker..... which then makes the air leak theory topsy turvey ? Or am I wrong? P.s I wish I had a servo.....
A weaker mixture is just as bad a richer one. mine would not idle when hot only when cold and the choke was working fine. I blanked of the inlet on the fuel manifold to prove it.
Have you an option to change the choke for known good one ? Seems a bit choke-y related to me ... To get the exhaust seated properly slacken off the heat exchangers SLIGHTLY , bolt up the exhaust and nip up the hx ...
Disable the choke by loosening the 3 screws and rotating it to 'off' position (i.e. fully open at cold). Drive - it will be a bit spluttery at first, but should warm up surprisingly quickly and be fine. Then try your hot start. If it works, then there is something up with your choke. If it doesn't then the fault lies elsewhere. This won't fix it, but will tell you if it is the choke for the sake of 3 screws and 15 minutes of your time!
Feel the manifold under the carb before restarting, it might be carb icing... The choke will mask this ,ie pouring more petrol down and ticking over cos it just might be hot enough...
The chances are you have set it up with the fault present so it runs properly, so when the choke changes things by operating properly it actually creates the appearance of a fault. As in @lost-en-france suggesting the kind of problem. I would check that the heater element in the choke has a resistance to earth all the time - my 34PICT-3 had a loose tag and I ended up carefully putting it on a hard surface and giving it a tap with a centre punch to re-rivet the connection . So you describe three conditions Cold start - OK : choke works everything cold so it pours in petrol Running - OK : after 3 miles , the automatic choke will ping off on a tap of the throttle and you will be running in no-choke mode. Hot restart - problems : This will be when the bimetallic spring in the choke will have cooled down and it has put the choke back on when it does not need it... Because that part of the carburettor cools down quicker than the engine. Just a thought - do you have a shiny bling air cleaner on top of that carburettor or the dark and ugly teapot stock air cleaner with hot air hose going in to it? If its a shiny air cleaner then the air going into the carburettor is about 30 degrees C too cold at this time of year so the carburettor will probably be set up on the ultra -rich side to compensate. So it acts up, with pools of petrol lying around and causing flooding on restart. The choke coming back on just makes it worse. If you do have the air cleaner, does it have the vacuum hoses properly connected to the hot air flap etc? These can have a double whammy effect of losing the hot air and acting as an air leak , smaller than a brake servo but enough to mess up idle unless again somebody has adjusted it with the leak present ...
