UK Car Repair: Renault 19 8v RT 1.4i ENERGY ENGINE, fuel pressure regulator, evaporation problem

Question
QUESTION: Hi there i am having trouble starting when the engine is hot.

when the engine is cold it starts up. Have you got any  ideas what this could be? thank you from mitch

ANSWER: Hello, this is fairly common on many cars, it is usually caused by a fault in the emmisions system or a loss of fuel pressure.  First look for a vacuum hose disconnected anywhere, other than that there are two things you can try;  First, when it is hot, with the car in gear,(make sure the car cannot start in gear by first trying it with your foot on the brake pedal) turn the key to the start position 2 or 3 times, now in nuetral, try starting it and see if it is any better. If it does it is caused by an internal fuel pressure leak! If it made no difference, press the accelarator pedal to the floor and try staring the engine, if it starts better it is an evaporation problem.  Let me know.

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QUESTION: Hi there thanks for your fist advice, i tried what you said about starting in gear and it made a dramatic improvement. I replaced the fuel filter and noticed there was no pressure in the fuel line, i have bridged the fuel pump relay and found the pump to be working ok. I have a single port GM type throttle housing fitted, and on that is a fuel pressure regulator basically a diaphram and spring set up, would a fault in this cause loss of pressure to the whole system? I am losing pressure after approx 3 minutes, also is this replacable as a single unit or do i need to replace the whole throttle housing...Many thanks for your help. Mitch

Answer
first you need to connect a fuel gauge into the system between the pump and the regulator. There are four ways it can lose pressure; an external leak, a faulty one way valve in the fuel pump, a faulty (stuck open) pressure regulator and leaking injectors. No 1 is out, no 4 you can check by smelling the engine oil to see if it is contaminated, press reg, you can check by temporarily blocking the return line, (be careful with temporary blocks as the fuel pump can build up enough pressure to destroy itsself).