Starting problems hot engine

[peteatreat]

Hi.
Went to start my series MM sidevalve today after 2 months of standing and she fired up on the 2nd turn. Went for a spin and stopped to get fuel after about a 5 mile run. In the time it took to fill up and pay, upon my return, she would turn over fine but just wouldn't start. Fuel pump clicking as it should but no luck. After letting her cool down for about 10 mins she started. After a couple of minutes she got a little lumpy and lost power I struggled on for a while it cleared and was fine from there on.

I think it might be fuel starvation/evaporation?

Please could I have your thoughts and ideas of how to cure or prevent it happening again.

Thank you
Pete

[Trickydicky]

Your describing a classic ignition problem, either the condenser or the rotor arm failing.

[bmcecosse]

If the fuel pump was ticking - could be the carb is flooding over. If it happens again - hold the throttle full open and crank it. DON'T touch the 'choke' !

[DAVIDMCCULLOUGH]

Is it an early MM with the carb bowl beside the exhaust? Mine used to suffer from this problem, its a May 1950 and the carb was going to need rebuilding anyway so I changed it to a slightly later one with the carb to the front and it cured the issue, Morris also did this in about 1951? Another change I made was to re locate the fuel pipe as its only about an 1' from the exhaust, it now runs accross the gearbox, up from above the starter and along below the battery box and then up to the pump.

[mike.perry]

The USHM3 engines were fitted with a bakalite spacer between the carb and manifold which also helped

[peteatreat]

Thank you for your replies.
I will check and probably change the rotor and condenser as it is due for a service anyway.
David, it is a Feb 1950 and believe the float bowl is close to the manifold. Based on what you have suggested and from other posts, it is probably down to fuel vaporisation. There seems to be various things I can try ie fitting a heat shield, insulating the bowl and of course the suggestions mentioned here.
I shall experiment to see what works.
Thank you all again for your help.
Cheers
Pete

[mike.perry]

Fuel vapourisation is one of the options but is more likely in hot weather, the clue will be rapid fuel pump ticking