525EFI Warm start problem - ??
 

Recently replaced the long block on one of my 525's. The motor runs great but I'm having a pesky problem with warm starting. When the engine is cold, it fires right up. When the engine's been idling for 10-15 minutes and is restarted, it fires right up. When the engine has been run for 45-60 minutes and then immediately restarted, it fires right up. However, when the engine has been run for that same amount of time, then sits for an hour or two (as in a stop for lunch); that's when the problem kicks in; the engine has cooled down somewhat, but it's still warm. It takes at least 3-4 turns of the key to get it to turn over. Pushing the throttle forward a bit seems to help it along but I shouldn't have to do that. Every other starting scenario, the engine lights up as soon as I turn the key. I've already replaced the IAC, the crank position sensor and the cam sensor and pressure tested the headers.

Any other ideas?

Almost sounds like a vapor lock issue. Next time you stop for lunch or something leave the hatch fully open so the heat doesn't stay in the engine compartment and note if the problem changes at all.

I leave my hatches open every time after running to let things cool off. Makes no difference for this problem.

Maybe use a Rinda to scan before and after the problem to pinpoint? I am looking to buy one to keep an eye on everything.

In my book, turn over means turn over ie: crank over.

Running means running.

So, just to make sure, as others are assuming you mean running, is it not cranking or not running until 3-4 turns of the key.

It is not running until 3-4 turns of the key. That is, the engine will crank normally but not start running until 3-4 turns of the key. With each successive turn of the key it seems to get better, ie: first turn of the key, the engine cranks but nothing happens. 2nd turn, you can hear a few cylinders fire as I start to hear exhaust noise but doesn't quite fire up, 3rd or 4th, she starts running. If I turn off right after the start and try to restart again, the engine will fire right up... bizarre..

your also cycling the fuel pump at the same time, maybe the system is losing pressure over a period of time and not holding adequate rail pressure

Good point. Mechanical fuel pump starting to go?

u have a fuel presure gauge on the dash?

Hmm.. interesting but I just replaced all three mechanical fuel pumps two months ago..