I have a 96 blazer, 4x4, with 4.3 vortec. About a month ago I replaced the fuel pressure regulator because of hard starting and rough idle, the mechanic said that's what it was. Ran fine for 4 days then died on me while driving, sat for a month and then I had the fuel pump replaced with a Delphi. Got it back and ever since, I have a hesitation taking off from a stop, under driving conditions it seems fine. I notice a vacuum leak coming from the brake booster hose to the top of my intake manifold. What is that part that fits into the top of the intake manifold and could this be the problem? That is where it is leaking from, around the base where it fits into the intake manifold cover. I will try to fix it tomorrow but I don't even know what that is and just wanted to know. Thanks

 

That is just a plastic 1/4 turn fitting with an o-ring seal. It is possible that the o-ring has been cut somehow... It is likely that the mechanic who did the FPR replacement messed it up.

 

That is exactly what happened. Thanks

 

Did you replace the o-ring? Did it cure your hesitation issue?

I am just trying to get the full resolution so that anyone who may be experiencing the same problem later on may find this thread useful.

 

When I got under the hood I could hear the hissing and went straight to that elbow fitting. It looks like the oring may have been stretched out or flipped and the elbow pinched the oring causing the elbow to not seat properly from what I saw. I did replace the oring, $1.13 from dealer. The hesitation went away immediately but now I have the dreaded P0440. Came out of nowhere, giving me other stuff to check.

 

Reset the code and see if it comes back.

In the mean time, read up on the code:
P0440 - Evaporative Emission Control System

 

Will do. I do smell some fuel under truck by tank but I just had pump replaced, I hope they didn't break a hose or valve. But resetting the code will be my first recourse for sure. Thanks and if I find anything useful I will post it.

 

96 blazer, 4x4, with 4.3 vortec with new fuel pump and P0400 code. Well, cleared the code and it stayed off for about a week. It seems to have come on around the same time as before, about a 1/16 less than half of a tank. I haven't noticed any broken lines under there or at evap canister. Is the purge valve on the fuel pump towards the front of the tank? If anyone can narrow this down for me a bit I'd appreciate the help. Thanks