Unable to start between cold & warm

V

V8P6B

Member
After the trilas & tribulations of getting my car through its MOT, I went to the garage to fill up with fuel last night. It wasn't especially low, and I hadn't pulled the reserve. After I filled up, the engine wouldn't start, wouldn't even fire. The garage is about 2 miles from my house, and although I had pushed the choke in, it wasn't overly warm, about 1/3 of the way up on the temp gauge. Anyway, I eventually had to push the car off the pump, and flattened the battery trying to start it. When the other half turned up with the jump leads, we eventually got it running but only after a long crank with my foot hard on the accelerator. The symptoms are as follows:
1: Starts ok cold with choke, and starts ok warm without choke, although it usually requires a bit of cranking when warm.
2: When the car is in between Cold & Warm, it will not always restart after being switched off
3: Not overly smelling of petrol when this happens, and was running fine before being switched off

Car is a 10.5:1 engine, with HS6's, pertronix ignitor II and Flamethrower II coil.
I do have a HIF6 manifold & carbs at home. Is it worth refurbing this and fitting it? Do HIFs suffer less with vapourlock, as this has been an issue on HS6's in extremely hot weather.

Car could probably use a tune up, so will be looking at plugs etc in the next couple of days.

Anything obvious? It does sound like its getting flooded.
 
I had a similar problem. Was a stuck choke. Look at the bottom of the carbs and push the bit that sticks out down below by hand in towards the main body.

Clean and lube the linkages.
 
If it will only start in these circumstances with prolonged use of full throttle, it definitely points to overrich mixture and probably to flooding . Needle valves ? Punctured float(s)? Float level(s) set too high ? Fuel pump pressure much too high ? Or just plain rich mixture on the mixture screws ? As Peter has suggested, first check for sticking choke mechanism. Incidentally, I have always thought that HIF were really nasty things ! I always have had better results with the earlier types such as HS and HD which didn't have all the nasty emission control stuff on them - bi-metal strips etc
 
yup check the linkage then check the carbs over and start dismantling. It's not a long winded job... few hours maybe,
 
Cheers guys. I'll check the choke linkage especially when I have also noticed that if the car is left ticking over it runs slower & slower until it stops. Also points to rich mixture at tick over. I'll also have a look at the thread on setting g up the carbs cos apart from cleaning the dash pots and pistons I've not ever touched them.
 
V8P6B said:
I have also noticed that if the car is left ticking over it runs slower & slower until it stops. Also points to rich mixture at tick over. I'll also have a look at the thread on setting g up the carbs cos apart from cleaning the dash pots and pistons I've not ever touched them.
Click to expand...

That sounds as though we're getting closer. It goes rather against the idea of a sticking choke or punctured float , ( where the effects relatively speaking would be constant ) and more in favour of the fuel level slowly rising
in the float chambers under low fuel usage conditions . That points towards needle valves and/or excess fuel pressure. No more than 3lbs/sq.in ( 0.2 bar ) is needed for SUs
 
That makes sense. I've checked the choke linkage, and it doesn't seem to be sticking, the jets return to the correct position when the choke is pushed in. The fuel pump is the original mechanical type, although it was rebuilt a couple of years ago, but wouldn't have thought it would cause too much fuel pressure at tickover at least. I think I'll get a service kit and strip and rebuild the carbs one weekend. The jury's still out on whether I rebuild the HS6s, or plump for the the HIFs though. The HS6's would be a quicker job, with no manifold change, but I've also heard say that the HIFs don't seem to drift off tune as much as the HS6's
 
This is going against the flow, but before you start to pull things down check the fuel tank breather and make sure it is clear. It looks like your car is a later model but the fuel cap seals very well and a blocked breather will flood the engine as the vapour expands. The fuel gets hot on its round trip across the engine and back and if you have just filled the tank there is nowhere for the fuel to go so it pressurises the carbs. The later cars with vapour control systems have the pipe running up under the roof gutter and down the driver's side pillar where it can get squished, particualrly if you also have a sunroof as it shares the gutter with the roof drain plus any gunk coming off the roof.
 
I should mention the quick way to check for flooding is to remove the bells and pistons and watch the fuel come out of the hole where the needle goes. This is best done on flat ground but it is worth trying it on a downhill as well.
 
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