brucetrentcamaro212

I started to check to see if my injectors wear leaking by lifting the fuel rail and turning the key on and no leaking. I have replaced the regulator and a new fuel pump. And still having hesitation all over my throttle. It has a check engine code. and it says the o2 sensor but I have replaced all of them. So I figured I either have put my fuel rail on and messed up the injectors or I need them cleaned and if thats the case I need to know how to clean them. If anyone one could help me out on this one....

2000GTP

What year car do you have? What is the specific code? Regardless of replacing the sensors themselve, you could have another related fault such as faulty wiring and that can very well lead to a poorly running car.

brucetrentcamaro212

Its a 96 Z28 I have replaced the o2 sensors and I have noticed hard starting after leting it sit for a bit. have to pump the gas a few times and crank it over 2 or 3 times to even get it to start. Just maybe going to try cleaning the injectors 1st to see if that helps before I spend any more money. Just wanted to know how first but It could be something else also.

2000GTP

A pressure flush would probably be the best method of cleaning. Otherwise, a fuel tank additive like Chevron Techron has had good feedback. With the problems you are describing, it sounds like the symptoms of a bad check valve in the fuel pump. If you have access to a fuel pressure gauge, you should see what it is doing.

MTL_Z28

I'm assuming a bad check valve in the pump would cause pressure to bleed off prematurely after the car is shut off? If so, how long does it normally take for fuel pressure to bleed off?

brucetrentcamaro212

I have no qlue what this bad check valve is your talking about. Where is it located at and how do i check it. also would taking my injectors out and cleaning them with fuel injector cleaner work I did try the fuel injector additive and not any better. It stubbles at all rpm ranges and if I floor it it stubbles everywhere and then about 3500 to 4000 rpms it seams to die intill i let off the peddle and then it runs still but stubbles everywhere still. It says in the manual that the injectors can be damaged when taking the rail off would that be the cause. Stuck on this one the car really messing with me now

2000GTP

The check valve is a part of the fuel pump itself. Here is a good tutorial in troubleshooting fuel related problems. http://shbox.com/1/4th_gen_tech2.htm...essure_testing

brucetrentcamaro212

Ok I say you guys are right. I pressure checked the system and found out that with the key on not running its at 20 psi and with the car running its 29psi. I didnt rev it too much b/c it dont want too to well but I did notice the psi dropped quickly. its seams too be a fuel pump problem I think but I just bought this walbro and only ran it for about 2 weeks and now this dont make sence. Could I installed it wrong or just a bum pump.

2000GTP

Did you flush the gas tank before installing? With those higher flowing pumps, it is recommended that you clean the gas tank of any old sediment before installing as the crud can lead to premature pump failures if sucked up.

brucetrentcamaro212

ok I found my problem today so i thought I would post the solution. Even though its my mistake. I pulled the pump back out and notice fuel leaking out around my fuel hose so thats were I was loosing presure. Back to normal now all the fuel presures check out fine now.only thing left is a valve adjustment, But im not doing it so it sould be done right How much power increase can happen through adjusting valves, They rattle pretty back and I havent had any low end torque sence they start to be out of wakkcool:

2000GTP

Out of adjusted valves can definitely lead to some power loss, or even worse depending how bad they are off.