Sometimes I just ignore these long threads thinking that with so much advise there can't be much to offer. Well this one sure ruins that idea. What a bad bunch of advise. Wrong numbers for OVP relays. Characterised auto diagnosis. Repair advise based upon the "blue car theory". That theory states that if it was a blue car the ...... must be the problem (fill in the blank).
Parts that go bad either do or don't do something. As a diagnostic technician I cringe at any diagnosis that isn't based upon testing. AND testing is based upon hypothesis. A bad OVP relay can do one thing only. It can reduce or eliminate power to control units it suppies. Do any of these control units have anything to do with hot starting. Actually NO!. Idle will be raised when hot by not powering the idle valve through the KE controller. The fuel enrichment starting will be gone but plays ever so much less of a part than it does cold.
The OVP can also just reduce voltage (acting like a resistance to the circuit). When doing this the idle can drop and cause stalling and poor idle. If this was the hypothesis, I would disconnect the idle valve and see if it made a difference to the problem. In other words draw an hypothesis based upon knowing the system and pick the easiest way to evaluate the hypothesis.
The NUMBER ONE, all time answer, for hard hot starting on any K, K-Jet w/Lambda, or KE system is fuel pressure leak down caused vapor locking. This leakdown doesn't matter to cold starting as pressure builds almost instantly. On a hot motor if you release the pressure the fuel boils in the injectors and lines. This messes with fuel delivery.
Here is where diagnostics gets complicated. I can give you many simple ways to evaluate whether OVP could be the problem (other than parts replacement; which is one way), but I can not tell you any way to view the simple problem of fuel pressure leak down except to put a gauge to it.
I would never use the "blue car" diagnostics to suggest that fuel pressure could be the problem. But, I will always promote diagnostic concept.
Bosch Master, ASE Master, L1
33 years MB technician