Andy A

Went to pick up the passenger side fuel rail to install it and noticed that the cap on the fuel pulsation damper was off and a screw was sitting loose inside of it.

Did some searching and it looks like a common problem. What I did not find searching was does the screw just go in tight or is there some kind of adjustment/setting that it needs?? What about a little bit of locktite on it to keep from backing out again?

thook

It's not adjustable, and it does need to be able to move. Read this on pg.19:

http://www.autoshop101.com/forms/h42.pdf

Andy A

Thanks good read, so basically screw it back in till tight and go.... What about a small dab of locktite to keep it from backing out again???

Wonder what they mean exactly when they write "calibrated at the factory"

"The screw mounted at the top of the damper provides an easy check for fuel pressure. When the screw is up it means the fuel rail is pressurized. Under most conditions, the check is adequate. The screw is nonadjustable and it is used to calibrate the damper at the factory."

thook

What that means is it's set to function properly and then no longer requires any adjustment afterward nor are you able to....... no "field adjustment" possible. For example, FSM is typically referred to as factory service manual, but it's also known as the "field" service manual.

Read this.....
https://www.yotatech.com/forums/f120...damper-150625/

myyota

You could probably put the screw back in place, but not knowing how its calibrated might cause a problem. See if you can find a used one for cheap and go from there.

MudHippy

Yeah, screw it back in till tight, loctite if you want. But, if yours still has the cap then it would catch the screw if it backed out again anyway. About a year ago I retightened mine, after looking under the cap and finding it so loose it had just about fallen out like yours.

It doesn't really serve any purpose under normal conditions, other than being a quick check for fuel pressure. Since there always is pressure in the system, the screw is always out. If pressure in the system is lost somehow, the screw would keep the diaphram from over-extending due to the rebounding of the dampening spring. So it might need to be there in case of that happening.

How they "calibrate" it?

Don't know, don't care. Just as long as it works!

thook

Actually, it does serve a purpose, MudHippy. It helps even out the fluctuations in fuel pressure created by injector pulsation. Minute drops in rail pressure occur everytime the injectors pulse. It's also a quick check too, though.