I'm putting the finishing touches on my LT1 swap. when I'm starting it either first thing in the morning or after its been sitting longer than 10 minutes or so it literally takes 15 to 20 seconds for it to fire up. But, once its running and I shut it off then crank it, it fires right up. most everything on the engine is new: opti, coil, plugs+wires, fuel pump, injectors.

thoughts and or ideas? Thanks in advance!

 

Fuel pressure regulator is bypassing.

Or fuel injector is leaking.

 

Agreed as the #1 possibility.

Get a fuel pressure gauge on it, and see what fuel pressure it is at idle and driving around. It should be about 43-47psi like a thirdgen. It should NOT drop below that. If it does, you have either a weak pump, or a voltage issue at the pump.

After you drive it around, park it and shut the car off. The car should hold above 40psi for quite a while. If it doesn't hold, either a injector is leaking, or the regulator is bad.

 

My pump seems ok, I get around 44psi at koeo. and when i start it up it bumps to 46psi and when i rev the throttle i get just over 50psi. when i shut it down it will hold at around 40psi for 10 minutes then drops maybe 1psi every few minutes until until its at zero... over an hour later.

 

mine acts the same way- during that long crank i usually just tap the gas and she wakes right up.

~Steven

 

Do you have any issues once the car is running. because mine will bog down if i try and do a brake stand or if i just dump it from a stand still. I was playing with the throttle a bit when i was testing the fuel pump i can say whether it made a difference though. I'm thinking i may have the wrong type of oil pressure sender... maybe. at least for the long cranking.

 

when i was running with open headers i had backfires if i tried an engine stand or even coasting sometimes above second gear.

now that i have pipes and a muffler i havent noticed it as much, but yes i know what you're talking about.

~Steven