[nabit]

This maybe the dumbest question ever asked but I need clarification please..

diagram 1..On a regular fuel system for carb application the regulator goes before the carb to adjust the fuel pressure to around 7psi thus keeping the fuel pump from pushing to much psi and blowing fuel pass the needle and seats..

diagram2..ok so how is the fuel pressure regulated in a bypass/return style regulator system when the regulator is mounted after the fuel enters the carb thus no regulation before the carb thus high psi pushing fuel pass the needle and seat?

diagrams
http://www.docstoc.com/docs/4294501/barry-grant

thanks..

 

[bowtie0069]

It just lets the fuel blow right on thru at the correct amount of pressure--it doesn't deadhead, so it doesn't build up pressure at the carb.

 

[nabit]

So if the pump is running 20psi and the regulator is set at 7psi doesn't it back up at the regulator and cause it to back up into the carb?

An analogy would be trying to regulate the water over a damn at the bottom instead of at the top..It doesn't do any good once it goes down the damn...

I know I am looking at this in a weird way but I can't quite catch the idea of it.

 

[D-Man]

Simply put, a regular (dead-head) style fuel pressure regulator controls fuel pressure on the OUT PUT side of the regulator which causes the excess fuel pressure to build up on the INLET side.

A By-pass style regulator works just the opposite. It controls the pressure on the INLET side (or line pressure) and bleeds of the excess off through the return line. Even if the pump is capable of putting out 80 PSI, if the regulator is set to 7 PSI, no part of the fuel system (even the pump) will ever see it.

 

[nabit]

thanks I appreciate it!!

 

[SlickVic107]

In simple man's terms:

Once the fuel gets above 7psi, the regulator opens allowing more fuel to be returned to the fuel cell, dropping the pressure to 7 psi. Just like most mechanical fuel injection systems use a jet in the return line. The bigger the jet, the leaner the system because it allows more fuel to go directly back to the fuel cell.