FYI recent auction prices for XJs from BAT:
Been a while since I posted - have fixed a few small issues - tuned it correctly (was miles out), fixed an oil leak from one of the cam covers, replaced the viscous fan hub (had a brand new one off my 1985 Range Rover which is the exact same part), replaced the faulty fuel pump and also fixed a small coolant leak.
Now it’s cooling down over here in Australia my attention has turned to the choke or cold start - whatever it’s called on these as it is a monumental bitch to start on a cold morning. There is a solenoid and wire on one of the carbs which I believe is to do with this, but not sure how it is supposed to operate as the wire was hanging off it when I bought it but connecting it does SFA as well.
Any thoughts or experience anyone has would be greatly appreciated as I don’t think my battery or starter will survive much longer without getting this sorted,
TIA - Gavin.
I threw away my AED (automatic enrichment device) which had been converted to a manual operation, I have jerry rigged the choke cable to pull down one of the jets, not an ideal situation but it does help with the starting on our colder mornings 6-7deg C 
When I get the XJR repaired and back in regular service I might look at improving the set up to operate both jets.
There are a couple of types of AED. My Series 1 XJ has the variety operated by manifold temperature - it’s actually a special SU carb to aid starting. It has no solenoid or electrical connection. Could you post a picture Gavin? There is an electrically operated variety - I have one on my Mk2 - didn’t think anyting like this would present on an XJ? Paul
1 Like
find a coupe. at least you will something worth wailing and knashing over.
What have you got ? , the cylindrical ASC (Auxilliary Starting Carb)
or rectangular AED (Auxilliary Enrichment Device)
An XJ will start very easily if they are working
The ASC is an easy fix
the AED, which I think you would have, not so much
My HS8 XJ engine has the AED removed and a manual choke, its great
1 Like
**
Tony’s question is pertinent, Gavin - it’s important to identify whether you have the AED or the ASC…
The latter is controlled by a solenoid, with an electric connection to a thermostatic switch - which senses coolant temp and vary solenoid opening. The solenoid is powered from the ign switch in ‘crank’ and ‘run’ with another wire…
The solenoid just varies the air opening - and adjustable needle controls the mixture.
If you have the CSI which the wire seem to indicate - there is no electrics on the AED…so…
Frank
xj6 85 Sov Europe (UK/NZ)
**
1 Like
Thanks for the replies - will get some pics tomorrow if I get home before dark - it looks a little like the second photo above - the ‘hisser’ - it has a wire running from it to a switch up the front of the engine which I assume grounds when cold. I haven’t checked the supply voltage yet, assume it could be why it isn’t working. How does this system actually work - can it be ‘manualised’?
FYI - it was 2 degrees C this morning so bloody hard to start without anything working,
TIA.
If it is the hisser then about the only thing you can manualise it is to use a remote switch in the cabin.
When working correctly the otter switch by the thermostat operates the hisser until it reaches a certain temp. This can be fooled into turning off by a quick flick off/on of the ignition switch.
1 Like
**
If there is power to the ‘hisser’, Gavin - you can ground that wire before cranking. This will then open the air passage and supply the required extra air and fuel for a quick start…
If this makes no difference to starting; the cause is either lack of power - or some other fault. The device is very crude - with fairly simple faults…
The ‘switch’ up front is indeed a temp variable resistor; depending on the engine temp the ‘hisser’ opening varies to meet engine criteria. As Robin says; manual override depends of the ‘hisser’ actually working properly…
The cold engine has considerable ‘drag’ and cannot idle on carbs only - hence cannot start. The ‘hisser’ is just a primitive extra carb; it adds extra air and fuel for a higher idle to overcome drag. And is set to fatten the mixture to counter initial fuel condensation and bad mixture dispersion with a cold engine…
The hisser’ needs electricity and fuel - and some adjustment…
Frank
xj6 85 Sov Europe (UK/NZ)
**
1 Like
VSo, finally got around to having a look at the cold start - a dodgy earth from the temp switch on the engine was all that was stopping the solenoid from operating, but that actually made it so it wouldn’t fire at all - I can get it to fire when disconnected but not when the solenoid is energised. Looking at it I’m guessing it’s only getting more air but no fuel - where does the fuel come from, there’s no fuel line going to this area - just the fuel to each carb and can’t work out where the fuel is supposed to go if this is to enrich the mixture - this engine has been messed about with, so I’m thinking maybe something was left off.
FYI - I now have a manual but the bit on this aux starting carb isn’t really clear to me on how it operates.
Pic of my setup for reference.
Untitled by Gavin Gregory, on Flickr
**
You have verified that the solenoid is activated both with ign to ‘on’ and in ‘crank’, Gavin…?
The fuel passages are internal inside the ASC, and the mixture from the ASC is fed into the manifold by the aluminium tube shown in the picture. However, the air into the ASC is not shown - where is it?
That said; the fuel is, as Robin’s drawing shows, slaved to the carb’s float chamber. Which makes it dependent on fuel level in that carb - and of course the connection to the carb, ‘41’ shown, being open…
Basically; two banjo bolts ‘42’ and ‘45’ in the drawing provide the connection through ‘41’ - and either may be clogged…
Suggestion; unscrew the banjo bolts, either one at a time, to inspect that both the banjos without necessarily disconnecting the bracket ‘40’ or the connecting arm ‘40’. Or indeed remove both banjos to inspect the entire connection (lots of sealing washers). Either operation should be possible without disturbing the carb…?
Then reassemble and try starting. If still unsatisfactory; check carb float level - though I suspect the main problem is the interconnection being clogged…
As an aside; the carbs themselves are set up to run a hot engine - hence mixture is lean, creating cold start problems. And the extra, unfuelled, air from the ASC makes the mixture far too lean for a cold start…
Frank
xj6 85 Sov Europe (UK/NZ)
**
1 Like
the air is drawn down thru item 30…making it “hiss” loudly when operational
once you have verified it works, just by earthing it should click on & off ?
take the top off and makes sure the spring & valve is seating and not damaged…its easy to drop this part
check the needle is set ok, with the nut, using the service manual
next take out the 2 screws below the wires in your pic, remove the metal cover…look down the 2 drillings with a light…there should be fuel, (which is one reason I dont like them)
my first XJ6 was very hard to start till I figured out the ASC was not working, they start easily once fixed, and are a very simple device
1 Like
Thanks as always for the prompt replies. Yes it does operate both on crank and with ignition. Just seems to be no fuel - Frank - that’s the conclusion I came to as well, more air, no extra fuel so gives me somewhere to go. I’ll do a few one other checks next time I have a moment and let you all know. 
1 Like
Interesting reading about the senders - the gauge on my right tank reads full for about 2 minutes after driving away from the gas station, then starts flitting and soon drops to E where it remains solidly until next fill up. It has done this consistently for 2 years and 10k miles. Changeover works fine and gauge on left tank works well enough.
I’ll have to have a look in there some day.
**
So any timer during the misbehaviour on the ‘right’, Martin - when you switch to ‘left’ it always show the correct level…?
The ‘right’ sensor is ‘of course’ faulty - reading correct at top-up. Level dropping; the resistor reads ‘break’ for the rest of the sweep. You could fill ‘right’ and drive on ‘left’ - checking ‘right’ occasionally, for the fun of it - though it is unlikely to bring more enlightenment…
Frank
xj6 85 Sov Europe (UK/NZ)
**
Your sender is kaput Martin and makes contact only in the full position.
If it’s a series 2 or 3 you can access the senders very easily, they are behind the tail lights.
The tanks have to be less than a third full though.
You can take he sender apart and you might be lucky and it could be repairable.
Otherwise putting a new one in is a 10mn job.
Aristides
Some S11 (my one) have the sender accessed from the rear wheel well.
Could the float be punctured such that when the tank is empty the float drains and as the tank is filled up so the float slowly fills and sinks to its lowest level (rinse and repeat?)