starting probs w/ new check valve

I had the typical slow starting (10seconds or so) and cold stumbling XJ problem on my '99, concluded it was the check valve and fuel drain-back, and installed the BMW check valve kit back near the tank - I figured as close the the stock check valve as possible was best - so it's just past the tank, in the first few inches of hard line. (This is a closed system - regulator at the tank, no return line.)

Works great - fires right up when cold immediately after hitting the starter, and no stumble - no matter how long it's been sitting. BUT, when it's been running a while and is fully warmed up, and I shut if off for just a few minutes (to get gas, run into a store quick, etc.), it doesn't want to even pop - not with several attempts to crank it over. Doesn't happen when it's cold, or when I just shut it down and IMMEDIATELY fire it up again - only when it sits for 5-10 minutes. The first time it happened, I just wanted to make sure it still had fuel - so I depressed the relief/test valve on the fuel rail - sprayed big time - lots of pressure...and then it IMMEDIATELY started. Happened again last night (I put the new check valve in on last Sunday) - so, after cranking a few times, I hop out and try my new trick - fires right up after I relieve some pressure.

Because it's a closed system with no return line, is it sitting and heat soaking - the fuel expanding, and the pressure rising beyond what the regulator would keep it at (the check valve is now in front of the regulator, so any excess pressure is retained by the check valve)?? And this excess pressure is preventing the injectors from operating correctly?? It's the only thing I can think of that makes any sense...but I wouldn't think it would be that sensitive to a little excess pressure.

Any other ideas?? Anyone else with this check-valve fix run into the same problem??

Thanks,

Huck

Run a search: there's something about protecting the injectors from overheating in these contidions.
Specifically about injectors 3 & 4.
Probably when you squirt the fuel from the rail, you're also letting the vapors out.

Thanks for the advice, but I don't think that's my problem...never had an issue with that before...and it runs fine when hot...it just doesn't want to start when it sits hot for a few minutes. Once I get it to start, by bleeding off a little pressure, it runs fine. And otherwise, its working fine under all circumstances.

Anyone else got any thoughts, had a similar issue w/ respect to an added check valve? I suppose it could just be coincidence that it started just after installing the check valve...and it could be coincidence that it fired right up just after I bled some of the pressure...but I really doubt it. How do the injectors work?? Can excess pressure "lock them up"?

Buehler??? Anyone??

Anyone?? No mechanics here familiar with injectors?