I have a 1968 3.4 S Type. Twin SUs with the AED automatic choke.

Yesterday I decided to give my car an engine start and warm up as it has been sitting for a couple of months now not used. The temperature is just above freezing and the car sits outside under a carport. Turned the key and listened until the fuel pumps stopped ticking, set the choke to come on via my override switch, hit the button and she started first time. Problem is she ran for 3 seconds, the revs dropped and she cut out. Hit the button again and exactly the same thing happened. Tried hitting the button and then in the 3 seconds playing with the throttle to pick up the revs but it did not help.
Went under the bonnet and visually checked everything and it all looked in place. No fuel leaks. Glass bowl was full.
From under the bonnet I hit the solenoid button and she repeated what had happened before. I could hear the solenoid on the AED jump on and off when I disconnected the power wire. Reaching down I took hold of the top of the AED needle and pulled it up and hit the solenoid starter button again and she bursts in to life and runs smoothly as long as I hold the needle fully up. If I drop the needle it stutters and stops. Once it had warmed up I heard the solenoid on the AED cut out and now when I drop the needle the car runs smoothly.

Anyone with an idea why this should be happening?

I think when the weather warms up a bit I am going to have to take the AED apart and give it a service.
Is there a service kit you can buy? SNG do an acceleration Needle for £50 and a complete solenoid assembly for £111 but is there a service kit of springs and seals you can buy?

 

You are referring to an over-ride switch, whereas the factory installation was for an automatic AED. Even during the 60s when these cars were made, people fitted over-ride switches so they could turn off the AED instead of waiting for the sensor in the coolant to do so. Please confirm yours has this modification.

 

Go direct to Burlen Fuel Systems. Most helpful. They will sell you every spare right up to a new pair of HD6 Thermo's and Otter Switch. I know you have an override fitted.

Your solenoid may be sticking. Dirt? Corrosion? Do you have alcohol in your fuel yet?

http://burlen.co.uk/?___store=default

The Worlds Sole Manufacturer of Genuine SU Parts - SU Carburetters

e.g.
H Type Thermo washers pack - SU Carburetters

 

Frazer yes I have fitted an override switch into the electrics so I can disengage the AED from the drivers seat before the otter switch kicks in but this in no way affects the function of the AED.

 

There's nothing wrong, the choke needle is simply set too lean for the outside temperature.
Physically holding the needle up proves this.
Holding the needle up makes the car run when it's cold _ you are making the automatic choke richer by doing this _ turn the adjusting nut for the needle counter clock wise one full turn to keep the needle from dropping onto the choke orifice.
Don't enrichen too much though.

This type of choke is putsy, once you set it to start outside when it's freezing, it will be too rich if moved into a heated garage.
I keep my car in a heated garage, and the choke is set to start the car from cold when it's in the garage.
If I take the car on a club meet in the fall and the car is parked out side in the cold, it will not start.
I have to enrichen the automatic choke to get it to start.

 

Thanks Jeff I will have a look at adjusting it tomorrow and try again.

 

Jeff could well be right. These things need to be adjusted for your specific ambient conditions as we have stated so often on the Register. I had to adjust mine as it was over enriching for my mild conditions. Orlando has also commented on the Register. The question you have to ask yourself Rob is was it previously OK in these type conditions or not? If it was previously OK then something has changed. e.g. solenoid not fully opening the needle. If the conditions are abnormal then readjust the needle.

 

Glad to hear you're getting it sorted out. These AED thingies were the invention of the devil. Of course here in the UK there weren't the temperature extremes you get in the northern parts of the US and Canada. Jaguar were very insouciant about problems in what was, at the time, their largest overseas market. A typical story concerns a chap in New York who complained to Sir William Lyons at the New York car show that the heaters were inadequate, to which Sir William said "young man, you should put on an overcoat! !!

 

OMG, that's such a typical British response !
Button up your woolies if you're cold !