Thanks Bill ~ I was scratching my head because I only know Jags up to pre XJ6. I'm a Mercedes man & general cars after that. Purging the rail of hot fuel makes sense. Fortunately Benz cars are not prone to vapor lock.

 

Hi Bill,
I have used this trick in my 1984 XJ6 for years while living in Tennesee where it gets very cold. It gets the engine started from the first crank after priming. But never had to use it when engine is hot.

Then I purchased the 1965 S type and was having the cold start problem too, so I tried priming and it definitely helped to start the engine when cold.

To me it seems as if the fuel systems become unpresurized after sitting for a while and need re-presurising. As if there isn't any fuel in the lines???

Heck I am not an engineer, so who knows what goes on after the engine is shut down.
.

 

I must have been very fortunate in not having difficulty in starting cars. I usually wait after turning the ignition on for pumps to pressurise and fuel bowls to fill (and glow plugs to warm etc). Then I push the starter and if there isn't immediate life I'll prod the throttle. Almost invariably, engines start first time (and I've owned some wrecks). The prod on the throttle is useful with Dell'Ortos and Webers when the engine is cold and on fuel injected cars, like my Series 3 Daimler DD6, when it's hot. These are for the obvious reasons of some extra mixture from the acceleration pump in the former and to clear a heated fuel rail in the latter.

I have a friend who years ago had an old Morris Minor that he sometimes couldn't get to life and he'd ask me to try. Often I'd go through a show of laying on of hands on the bonnet. Strangely, it always worked.

 

Jose and all
The 3.4/3.8 engine in MK1 to 420 cars used an Otter switch to activate the electric solenoid in the SU HD6 starting carbie.
On numbers of occasions I have been contacted by owners of these cars who have difficulty in starting particularly in cold weather. (Queensland can get to sub zero C temperatures in winter in the high country.)
Invariably I advise them to short out the Otter switch and typically the report is it starts OK. I also advise them to make sure to to get rid of the short after the engine has warmed up

These Otter switches are supposed to activate at coolant temperatures below 35C but again and again I have seen them fail.
I advise them that a new Otter switch is needed or alternatively to run a wire to a switch somewhere in the dash panel so they can exercise manual control over the starting carbie. Most opt for the latter.
I personally recommend putting a pull on/push off switch just above the bonnet release knob where it is totally unobtrusive.
One side of the switch is the wire that goes to the Otter switch and the other side is to earth.

Simple enough to do and quite effective

Bill Mac

 

... which brings us back to the obvious with Josh's 2.4: make sure the choke/enrichment mechanism is working.

 

You are right Bill about that pesky Otter switch. One of the problems is that over time the cut out temperature can change so the problem I had was not so much starting but keeping the engine running after two minutes when the choke cut out because the Otter switch thought the engine was hot enough to run on its own. Two mins out from the house and there are several sets of traffic lights one on a hill and with an Automatic I could not get the revs up high enough to pull away and sometimes and I know its hard to believe but I would stall an Automatic.
My solution was to run a permanent earth from the Otter switch to the inner wing. I had already previously set up a switch on the dash to control the power going to the Otter switch so now I have a straight forward On Off switch on the dash. I find this set up so controllable so in the winter on a cold day even a couple of miles from the house if I think the engine needs the choke to get up a hill or pull away from a standing start I can quickly pull the switch, get the old girl moving then switch the choke off again. Just got to be careful with this set up that I switch the choke off once it is not needed of the engine will run really rich. I could have bypassed the Otter switch completely but in the summer I remove the extra earth and run the choke just on the power switch so don't have to worry about it staying on as the Otter switch will cut it off when it is summer hot.
Someone on the S Type forum did discuss that you could strip the Otter switch down and by bending the Bi metal strips extend the time to which it stays closed (effectively changing the temperature setting) but I have not got around to this yet.

 

What choke set up do the Solex carbs have on the 2.4. Does it run the Enrichment devise or does it have a manual choke. Not sure.

 

Manual choke with a slider control. (butterfly's)