Hot starting problems on '85 500 SEL

[Ben12345]

Hi

I'm having some hot start problems on my 85 W126 500 SEL Euro version, I'm getting what I believe to be vapour lock in the fuel lines, and hence fuel starvation causing excessive cranking under hot starting, and sometimes on cold starting if i've been on a long journey where the engine has fully warmed.
Once eventually started, I can hear bubbling in the fuel tank as if the vapour is getting purged from the lines.
Should my fuel pump run for a few seconds upon turning the ignition on? If not, is there a certain relay I can splice in to make this happen?
How do I know if my fuel accumulator is shot?

Kind Regards