MAF Sensor/Fuel Trim/ Vacuum Leaks

[Marcos Beltran]

I took a break from the truck today but of course its on my mind. I have a question and maybe someone on this forum could answer this. If my fuel system has a leak in it, how is it possible for the system to hold pressure? May not hold the ideal pressure but it does hold pressure. Shouldnt it leak down to 0 psi after a few minutes?

 

[Schurkey]

Kinda depends on the nature of the leak.

A plain ol' hole in a rigid steel tube would leak down to zero pressure. A leak across a gasketed joint might leak only under higher pressure, but sort-of seal up under lower pressure. A cracked casting might only leak when heated...or cooled...or under some other stress.

 

[Marcos Beltran]

Well i dont know what the hell i did but i put if all back together and damn thing is running a lot better. No more bogging down when the gas pedal is pressed. Fuel trims are in range also. Only thing i changed was the fuel pressure regulator( which was not visibly leaking to begin with) and pcv valve.