Been trying to figure this out for awhile, haven't found anything that actually helps and for some reason garages swear it never happens to them with my car. But we'll just take today, I'm leaving at ~7am to go to the store, it's a 5 min drive. I'll be there for 20-30 mins, and when I leave it can be hard to start the car back up. Now, I've got a small work around where I put the key to run for 20 seconds or so and then try to start it, and it will generally start then, but I do have to give it gas to start and to keep it from stalling then. Basically hold the idle at 1000 rpm or so for like 10 seconds and then it won't drop down to under the 600 it idles at. It starts fine when it's cold, and even warm, but only if it sits for 3-4 hours between startups.

So I've been leaving it run while filling up gas, and avoiding doing things where I'd have to deal with it as it has taken me 15 minutes to get it started before. There's been a lot of recent work, nothing has helped, it even got worse recently until I got the vacuum pump leak fixed.

One suggestion a mechanic said was take it to a dealer and get them to hook it up to the computer system and check if the idle is set proper and if the settings are right for it starting up, but then said it could cost around $4000 to do that so I have no desire to try if it that's expensive.

 

Is this a legitimate mechanic telling you this?

No dealer is going to charge you $4k for diagnostic, and especially not without OKing it first.

Certainly it will be expensive for them to diagnose, they usually run about $100 or so an hour, but no real shop is going to spend more than half a day figuring this out.

 

Fuel pressure regulator.

Cheap part, easy install,

We had hard second starts, replaced this and problem was gone.

 

So the mechanic who told me that is a neighbor. He works for a BMW dealer though.

But as for the pressure regulator, I'll look into that this week. Seems like a nice fast fix if it works, just gotta order it and wait for it to arrive to see if it helps.

Thank you

 

That certainly sounds like a lack of fuel volume getting into the rail. Once hot it will vapour lock, it’s basically boiling off in the fuel rail before it fills to make pressure.
Fuel regulator, fuel filter, fuel pump or a leaky or linked line are all suspects.