May have posted this before...but havent found a mechanic that has been able to diagnose the problem yet...98% of the time the Tahoe starts up fine justs like it should. Once a day (and not every day) and usually on the second crank...it takes about 3-4 attempts for it to start. Just turns over and over and---- well you get the idea. Pressing the gas pedal helps a little, but doesnt immediately make it start. Rest of the time it's "fine"... any ideas?

 

IF your mechanic is worth his salt one would assume he has checked the obvious....fuel pump,regulator,filter,plugs etc...

Could be as simple as dirty fuel injectors or bad gasoline since you say it is fine 98% of the time.

 

I've had two different ones check the fuel pump and both have come back saying that it's fine... this model doesn't have a fuel filter like normal...think there is only the sock filter in the tank....and yeah...you can drive it for several days and it won't do it...then whammo....it will take 3-4 attempts to start it.

 

I would want to see what the fuel pressure looks like in Key On Ignition off and Key Off positions... needs to be 55+ PSI running and steady and should not bleed down too quick once turned off...
Next up would be having the injection system professionally cleaned...
Might check the Cam and Crank position sensor connections...

 

The check valve in the fuel pump could be going bad. It sounds like at times your check valve is letting the fuel bleed back into the tank. My truck was doing this and I added an inline check valve and the problem went away.