I have a 2000 ZR2. Yes I have searched the forum and spent lots of time reading on the issue. Here is what I got:

It began when I first purchased the car and on the highway (70mph) after an hour or so of driving the car would begin to hesitate or surge. This was worse under load ie pulling a trailer. I have a trouble code the comes on and off and isn't always on when the problem presents itself. I can't recall the code number but it was catalytic deficiency on bank 1 S1-4 or miss fires. Recently I started having trouble with starting and really bad hesitation and loss of power at low speeds after the car had sat for a while.

I just changed the cat today so we will see what that does. My fuel pressure is 60psi when the ignition is on, motor is off, and the pump is running. At idle 55psi and quick flips of the throttle provided 55-60psi. The kicker is when I turn the car off I have 0 pressure within 30 seconds.

My questions are where should I start? Is the leak more likely in the fuel regulator or check valve on the fuel pump? Does it sound like the cat could fix my hesitation problems and that the fuel leak is a separate unlinked issue? I don't understand how the two would be linked why would losing pressure when the pump is off cause lean function or hesitation when driving? Thanks for your help and what will a leak do to the car if I let it go for a little bit?

 

A test of the fuel pressure at the fuel filter will isolate the pump and tell you whether it is the check valve in the tank or the FPR.

If the leak is at the FPR, you could end up with fuel in the oil, decreasing it's ability to properly lubricate your engine.

If the fuel pressure fluctuates during operation, it could cause a lean condition, but that would not come across as a catalyst efficiency issue. There are separate codes for that.

 

The two are not related. The fuel pressure leakdown is a problem, it must remain above 55psi for at least 10 minutes after the pump shuts off. The only way to determine if the leak is in the plenum or in the tank, (without actually taking it apart) is to isolate the fuel pump from the system immediately after it pressurizes the system.

 

thanks swartlkk for the quick response.

I saw that listed on the fuel test sticky what is the name of that tool and where can I get one. I guess it can be jerry rigged but Id prefer not to.

Would the FPG leak leave a noticeable scent in the oil because I've tried smelling it and it doesn't smell any different from regular oil?

Yea that's why I was confused because I seem to have good pressure when running and I kept the rpm's raised for a short period and didn't see any fluctuation. I'm hoping that the catalytic was responsible for the hesitation. The code I received from Autozone did mention misfires as well.

thanks captain hook it's good to know I didn't spend time and money on something that won't fix any of my problems. Also it doesn't seem difficult to take the upper intake apart I've had it most of the way apart. As I mention above I have no clue what part they are referring to in the fuel system diagnostic sticky.

 

You can make a shut off valve tool that goes inline at the fuel filter quick disconnect fitting. Cost is about $35 to make it. Plug it in, pressurize the system, shut the valve... if pressure drops, the leak is in the plenum. If it doesn't drop, the leak is in the tank.

I added a gauge to mine so I can check maximum pump output pressure too.

http://i561.photobucket.com/albums/s.../DSC_00022.jpg

 

Can I get some more details on this? Is there a specific name for this type of quick disconnect? Where did you get it? That looks like a regular ball valve and hose correct.

 

The quick connect fittings and the "fuel injection rated" hose is available at any auto parts store. The ball valve, brass adapters and gauge are available at any good hardware or plumbing store. Compression fittings are rated at 170psi, the valve is rated at 600psi, the rubber hose is rated for 150psi. Maximum fuel pump output pressure is only 108psi.

If you build it like this one, it will check regulated fuel pressure, maximum fuel pump output pressure, check for leakdown and determine where the leakdown is coming from, all by installing it at the fuel filter. Fuel pump leakdown will be indicated on this gauge, (not the pressure tester under the hood) when the valve is closed.

 

Thanks for everyone's help and thank you for the testing device captain hook.