Is It Age Creeping Up?

[WillySteve]

I've worked on stuff most of my 70 years. I know well Hydraulics and Fuel Systems BUT I have never been able to figure out the why's and reason's on the fuel rail set-up on a Merc 260!
Would SOMEBODY please explain the WHY of having the bypass hose below the regulator!
Having this hose would bypass the regulator and send fuel straight back to the tank which "in my mind" would at least partially defeat the purpose of the regulator.
I've always ran mine as it came from factory with no problems but I've really never understood the WHY?
403591

[Onetime]

It is not a full size tube, has a very small hole which allows air to bleed out when system starts up. Works really well, earlier systems without it could trap air in the line. The hole is small enough that trapped air can bleed out. The fuel pump has enough capacity that it is not a factor.

[Da Bull]

I agree with Onetime on all above plus a Merc Rep told me that they did not want pump psi sitting on the injectors and reg while engine is shut off. The tiny hole is suppose to be .014 and bleeds off psi from rail.

[WillySteve]

I guess I've never looked in the pipe for an orifice the times I've changed the hose....It certainly makes sense now!!!
Thanks Guys....it's all coming together now!!!!!

[90 5.0]

The first time i saw that I was sure someone rigged it up wrong until I figured it out too

[WillySteve]

I really don't know why I would even think about this after I've been running it for so many years! Jus popped up this morning! LOL