engine rebore and fuel pressure regulator

[upontheriversky]

hi,

i recently rebored from 72mm to 74mm piston, this increase in displacement would i need adjustable fuel pressure regulator? and still using stock fuel pump

and if i do, do i have to custom a return line? whats return line for is anyway?

thanks

 

[SkYwAlKeR]

need or not depends on ur AF mixture... get a wideband sensor to check..
all fuel line has a return line... if not, ur fuel injectors will receive maximum pressure from the fuel pump.... fuel pressure regulator is there to regulate the amount of fuel going back into the return line, hence increasing or decreasing the fuel pressure in ur fuel rail....

 

[upontheriversky]

thanks, but how do i go and do wideband sensor test? any tips on interpreting the reading?

 

[Izso]

A Wideband sensor will tell you if you are running rich or lean. If rich then you gotta lessen the fuel intake and if lean you gotta increase. Quite straightforward la.

 

[upontheriversky]

ah ok and use fpr to regulate for rich or lean condition..i get it.

my mechanic modded my fuel line, he added an extra fuel filter near 5" to the fuel rail, he said its good coz fuel pump produce carbon in the long run and its not being filtered by filter underneath it in the tank. he said the pressure wont drop by extra filter, i just wonder if its true

do you know any place can do wideband test? i want to do compression test too..both wet and dry to see if i have broken in the engine properly

 

[Izso]

There's no real "wideband test" I think. You need to buy a AFR wideband meter and see it real time.

Putting anything in the way of the fuel pump to the injectors will change the pressure la. What car do you drive? How come your car doesn't originally have a fuel filter?

Compression test you need to do at those workshops with the tools. Most Sunway performance shops have this or alternatively check with your mech

 

[upontheriversky]

is the wideband meter comes together when u buy fpr? i saw on the marketplace, it comes with the gauge and adaptor, is that it?

i drive kelisa, initially it already has fuel filter. it sited before fuel pump. so my mech installed another one after the pump before fuel rail in engine bay

sunway got? then ill drive and ask around for price

 

[Izso]

Uh... why the heck did you mech add another fuel filter right after the pump? That's just unnecessary imho.

The wideband AFR (air fuel ratio) meter is separate from the AFPR (adjustable fuel pressure regulator). Two totally different non-related items here.

 

[nyantong]

need or not depends on ur AF mixture... get a wideband sensor to check..
all fuel line has a return line... if not, ur fuel injectors will receive maximum pressure from the fuel pump.... fuel pressure regulator is there to regulate the amount of fuel going back into the return line, hence increasing or decreasing the fuel pressure in ur fuel rail....

Actually not all engines have return line. More advanced engines deploy variable fuel pump rate to regulate pressure.

 

[upontheriversky]

i know myvi doesnt have return line so usually have to custom right? if want to install fuel regulator

 

[Izso]

i know myvi doesnt have return line so usually have to custom right? if want to install fuel regulator

So this is a Myvi we're talking about? You need to mod the fuel line to include a return hose. I personally don't find a need to do this for my super stock car. Otherwise I'd post a DIY

 

[upontheriversky]

its actually kelisa :D im not sure got return line or not but i dont see any line going out from the fuel rail.

some ppl recommend me check a/f ratio after rebore, so after check then see if i need to install or not. i also think its not necessary but no harm checking

 

[alieamin]

my myvi i just changed the fuel pump to walbro 255lph, and sard fuel regulator, i noticed this 2 parts is imitation/taiwan made but claimed by accs shop this is original.

Anyhow i dont create any fuel return on my fuel rail, i can modi the fuel rail,but the return hose im not sure where to put it :p

most mech will dig a hole at tank? lol.

btw by changing this 2 parts,i noticed my car went lighter and more pickup. No need to press even half pedal.

 

[me2kimi]

I think myvi fuel regulator located inside fuel tank. Fuel are regulated inside fuel tank, therefore no fuel return line at fuel rail