just don,t forget to open the valve or you could ruin the pump.

cant hurt to try. Will rule out any fuel bleed off etc. what kind of efi is this? Also is there a pressure relay or something on these that signal the fuel to go back to the tank via fuel line like Mike touched on? Sorry I'm not much help on the subject but trying. fuel pressure seems low however might be completely fine for your particular set up. The problem I had was more of an issue when it sat for longer periods of time. If it sat for a week or longer it was very hard starting otheripwise wasn't an issue. oxygen sensor?

It's fairly common for a Whipple rear mount throttle body setup to have to crank quite a bit longer on the first start of the day. It takes a few rotations to get the fuel through the rotors and intercooler. Once they're all saturated it will fire much faster, even after sitting for a couple hours there is still fuel suspended in the intercooler facilitating a quick start. Whoever programmed yours probably needs to add some cranking fuel at the bottom of the table to help get it going a bit quicker by the sounds of it. Not a big deal, and not fuel pressure, or pump related most likely.

when you say cold,,how cold?air out side and engine.sounds like cold weather tuning is in order.I was blessed many years ago that my boat got cold soaked and there was ice on the deck up in maine.pulled out the lab top and did some cold weather corrections.now 12yrs later,still starts in 20° weather.
seems thats always the temp when winterizing my boat.

I have Teague EFI 800's and have the same problem after sitting for a day or more. I will wait for fuel pressure to build before I crank for a few turns. Then wait a few second, turn key on again, wait to right before pump shuts down and crank again. Most time on third try it will start. Rest of day only have to tap starter and motors are running.

Mine does the same thing, just like Haxby said. Just first start of day. I had a very similar set up except with vortech, instead of whipple and it started normal all the time. Its a whipple thing.

I've tried pretty much everything. I have great oil and fuel pressure, just doesn't seem to wanna fire like I want on the first cycle lol. Maybe it is a whipplecharger or this set up. Not to sure.

Is your regulator mounted before or after the fuel rail? If it is before, you could be generating a air pocket and is hard to clear. We recommend to install the regulator after the fuel rail. This will constantly flow fuel through the rail can eliminate the air pocket. Also, do you have an adequate fuel cooler or returning the fuel to the tank/s? -Eric

Have same problem with my 500efi with whipple hard to get fuel all the way down to cylinders after it drys up from sitting. Open the throttle body and give it a shot of starter fluid it will start and suck the fuel down.

I don't think that's what the problem would be, these motors are multi port injected below the intercooler so getting fuel down there should be instantaneous upon cranking. (unless) - I think it's what Teague is saying - must be an issue with air pockets in the rail / regulator.