bad starting when hot

starting from cold is good but after a good run swich off and back on it starts' after 5 mins turned off  it takes forever to fire up ..its almost stock 1800 golf GTI . k jet.

Sometimes the non return valve on the fuel pump fails, causing this problem

Maybe losing fuel pressure too quickly.
The  hot engine bay and low fuel pressure could bemaking the fuel boil in the lines.
Try priming the pump several times before cranking by switching the ignition on and off  You should hear the pump prime. if it doesn't then you may have an after market pump relay or a faulty one. The other way is just to flick the engine crank enough to make it see a signal at the dizzy. that should break the pump into life momentarily and rebuild pressure.. See if that improves it.
 

i had this problem it was the fuel accumulater 

I had a 'hot start' issue for about 5 years - on and off because it wasn't a constant problem.

It was eventually trace to the metering head. Once changed it never did it again (fingers crossed).

A lot of the parts involved can be expensive to replace (except the non-return valve). If you can, get hold of a pressure test kit and run the pressure tests as this can help to pinpoint the fault - I am going through this right now, and the test kit has enabled me to identify which parts of the system are working and which may not be, without having to buy any parts except some o-rings - so far!
Lee

if your fuel accumulator isnt too rotten there is a small screw on the back side of it, unscrew that. if fuel comes out either straight away or after car is running, your accumulator is bust

lots to try . i will start with the simplest .

thanks every one.

Is your fuel tank heat shield missing?

I had this issue and new accumulator sorted it 

It was the none return valve and a week battery . All seems good now . Thanks every one .