Engine has to cool down before it will restart

[msanford98]

Have an '84 Vanagon Westfalia 1.9 gas engine. Replaced fuel filter, fuel pump, temperature switch-both in block & thermo switch in fluid reservoir & injectors rebuilt. Replaced fuel regulator yesterday because engine had been running rough. I took it for a test run last night & the engine seems to run & idle ok. Once I shut the engine down, it did not want to restart. After about 1 hr, it restarted (cooled down). Does anybody have any idea what the cause could be? Would appreciate any help.

UPDATE: Discovered the temperature sending switch had come unplugged. Plugged it back in, took it for the same test run as last night and all seems to be ok...for now anyway. Thanks for all the feedback. Just another day in the life of a Vanagon owner!