Howdy,

My 4.7 is having trouble starting warm, acts as if an injector is leaking, flooding the cylinder (previous thread, rough start).

The service manual says that it’s normal for a cold vehicle to have 0 fuel pressure, due to the contraction caused by the temp drop. In the Leakdown test it tells me to warm the engine, then monitor the pressure for five minutes after shutdown, and it should not drop to less than 30psi.

So while running I have 49, normal. Immediately upon shutdown I have 45. It starts dropping very slowly. At 15 minutes it’s at 41, 20 minutes it’s 33, 30 minutes it’s 21, and in about 45 minutes it’s essentially zero. This is at about 48 degF ambient.

Does this look normal? If not, my next step will be to determine if the leak is on the injector side or the fuel delivery module check valves.

 

I have a 3.9 but that pressure sounds normal to me. The check valve in my fuel pressure regulator went bad and my truck took way too long to get started after sitting only for a few hours. I tested my fuel pressure and it had about 49 psi at idle but when I turned off the engine the pressure immediately began to drop and was at 25 psi and still falling within just 3 minutes. I had to replace the fuel pump to fix it.

I think your pressure is normal and you are on the right track by checking the injectors.

 

yep thats good pressure.