1990 E30 M40 hot start problem

I have an 1990 318i that is hard to start when the engine is hot but start with no problems when the engine is cold (in the morning). When the engine is hot, if I turned it off and started it again almost
immediately, the start is good. But if started it, let's say after 15 minutes or more, I have to start it at least 4 times before the engine will be running.
I recently change the fuel pump and fuel pump relay (Feb 2006), so the cause is not in the fuel pump. I take it to the local bmw shop, and the mechanic suspect a failure in the FPR, coil, coldstard, fuel filter or spark plug might cause those kind of problem.
Has anyone experience similar with my problem? Any advice will be highly appreciated.
Thanks in advance.
Riyandi '90 318i
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snipped-for-privacy@gmail.com wrote:

hmmm.... might be an idea to check the fuel pressure regulator too.. it's at the end of the fuel rail.
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I read in John Burns about how to check your FPR:
<quote> Probable cause is fuel pressure bleeding away. The FPR holds pressure at one end of the fuel rail and the fuel pump non return valve the other. Clamp each fuel line in turn after you stop the engine and leave for an 30-60 minutes. If it starts you may have found the problem. </end quote>
Has anyone ever try this procedure ? How to clamp each fuel line in turn ?
keith wrote:

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Places such as Halfords (UK) sell fuel line clamps.
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