'93 300 SE hard hot-start >>> HELP?
 

My bro's '93 300SE with ~ 140k has developed a hard hot(ish) start issue, hoping someone out here can point me in right direction.

Basically, here's what it's doing:

- 1st start in a.m. is fine
-5 minute to 4 hour or so sitting, starts fine
-7-9 hour sitting, car cranks and cranks, finally starts, runs fine
-12-24 hours, starts fine

Any insight greatly appreciated. Of course, car starts acting up as bro is over in da Desert and his wife is left with car that suddenly wants to misbehave! Typical.

Thanks!

A quick guess...OVP...if the current one is original!

Could also be a fuel pressure regulator.

Do a search on "hot starts"

G-Benz-

Thanks! OVP, that's the Over Voltage Protection relay or something, right? I know my 2.3-16 had one, up near the battery box.

Now, in da Big S, where would she be hiding? Any secrets to replacement? Best source / approx. price? DIY? I'm sure it's original.

I'll do the search now, though.

Thanks again.

I would expect a fuel pressure drop ( internal fuel leak ) may be causing the problem. If you don't have a fuel pressure gauge to attach, the most common problem is the fuel accumulator. If you get the engine to running temperature, pinch off the small hose on the accumulator & let it sit for the amount of time needed for the problem to happen, then try to start the engine. If it starts up right away thats your problem. The accumulator is located near the fuel pumps.

Thanks WRM-

Uh, where are the pumps in these cars? This isn't mine, so...

Also, "pinch off the small hose on the accumulator"... best way to go about that?

Thanks, remember, not my car, so yous gots to treats me likes the moron I AM!

I meant to refer to the "accumulator" not the regulator...sorry.

And I believe the fuel pump(s) and accumulator would reside just in front of the right rear wheel...a plastic cover protects the setup from damage, so get out your 10mm socket wrench to gain access...

you also might want to do a quick check on the fuel pressure regulator located on the back end of the fuel rail. pull off the vacuum line & check if there is moisture ( fuel ) there.