- Joined
- Aug 7, 2007
- Messages
- 1,842
- Points
- 3,101
- City
- Costa Mesa, CA
- State - Country
- CA - USA
- Other
- 2004 Bronco Badlands
- Vehicle Year
- 2002
- Vehicle
- Ford Ranger
- Drive
- 4WD
- Engine
- 4.0 V6
- Transmission
- Manual
- Total Lift
- 1.5"
- Tire Size
- 33"
I had a post about a problem I was having when travelling long distances on Interstates. Nothing was resolved and I didn't do any diagnostics because it is running very well on shorter trips.
I decide today to check out a few things to see if I could find any issues. I decided to start with fuel pressure. I found a Shrader valve on the rear of the right fuel rail. Its part of what is called the fuel pressure relieve valve in my Ford Service Manual. I attach my fuel pressure tester to it and turned the ignition switch to 'on' without starting it. The pressure would go up to about 50 psi and immediately drop to 0. I checked for leaks and tightened the connection more to make sure it was not leaking. I still got the same results. I cycled it several times with the same results. Then I started the engine and it ran very bad with misfiring. I then removed the fuel pressure tester and fired it up again. It immediately fired up and ran perfectly.
I don't know what this fuel pressure relief valve is supposed to do. It looks like it is just there to relieve pressure by pressing in on the Shader valve when work is to be done on the fuel system. I see no way for it to release fuel pressure any other way. There is no return line like there would be on a fuel pressure regulator. I am baffled why it ran so bad when I had the fuel pressure tester on it. I forgot to look at the pressure when it was misfiring at idle. I was so startled that I forgot the important part of the diagnostic. If I have time later, I may try that again.
I am seeking any information as to why it would do that.
I decide today to check out a few things to see if I could find any issues. I decided to start with fuel pressure. I found a Shrader valve on the rear of the right fuel rail. Its part of what is called the fuel pressure relieve valve in my Ford Service Manual. I attach my fuel pressure tester to it and turned the ignition switch to 'on' without starting it. The pressure would go up to about 50 psi and immediately drop to 0. I checked for leaks and tightened the connection more to make sure it was not leaking. I still got the same results. I cycled it several times with the same results. Then I started the engine and it ran very bad with misfiring. I then removed the fuel pressure tester and fired it up again. It immediately fired up and ran perfectly.
I don't know what this fuel pressure relief valve is supposed to do. It looks like it is just there to relieve pressure by pressing in on the Shader valve when work is to be done on the fuel system. I see no way for it to release fuel pressure any other way. There is no return line like there would be on a fuel pressure regulator. I am baffled why it ran so bad when I had the fuel pressure tester on it. I forgot to look at the pressure when it was misfiring at idle. I was so startled that I forgot the important part of the diagnostic. If I have time later, I may try that again.
I am seeking any information as to why it would do that.
