help with fuelling question (engine gurus/mechanics look here!!)

[geesus69]

can someone in the know just clear this up for me regarding fuel pressure regulators? basically how they work

on the clio for instance, they sit at the opposite side of the fuel rail to the feed, fuel pump pushes fuel into rail at whatever pressure, vacuum connected to regulator allows different levels of movement of the diaphragm dependant on throttle position (load)

so if the vehicle is at idle the vacuum is weak and therefore the diaphragm is 'released' (if you get what i mean by that lol) that reduces the pressure in the rail, therefore pushing less fuel through the injectors

in the same way if the engine is under load (ie throttle fully open) then the vacuum is strong, the diaphragm is held 'closed' and the pressure in the rail is high, meaning that when the injectors are opened more fuel is pushed through

am i right so far? lmao

if i am i think i understand how to rig up my regulator, you see i was originally under the impression that fuel would have to pass through the regulator before it got to the rail and that is how it sorted the pressure out (ie input in one side, output on the other, simple as!), whereas looking at the standard setup this is not the case as the regulator is at the other end of the rail and adjusts pressure by 'blocking' or 'unblocking' the return

god i hope im right as its been doing my nut in :S

 

[Dan@SJM]

Right, your kinda there. there is a high vacuum on idle as the throttle butterfly is closed, engine is then sucking creating a vacuum... so the diaphragm is pulled up against the spring releasing the pressure to about 0.7bar iirc. at full throttle there is little to no vacuum, so then the regulator spring is pushing the diaphragm back making the fuel pressure usually 3.5bar.

Correct on it restricting the return, but if you dont have a fuel rail that supported a fuel reg from the factory it will be sealed, so you can either drill it out and fit a regualtor or fit one inline.

 

[geesus69]

i thought you might reply to this one dan my saviour lol

right well the other day im sure found the fuel return pipe (it has the same connection as the fuel feed pipe), and it fits the return outlet so maybe mine did have a regulator and for some reason it got taken out? :S

also where the regulator fits is this groove, is this some sort of sign that there was never a regulator there?

so dan if i get my gob round the return outlet and give it a blow, is this gonna be the best way of knowing what rail it is?

if it is blocked its either....

a) drill it out and take out that groove so i can fit the dummy regulator

or

b) put it inline like wayne has done (trouble is i dont know where to get another connection for the regulator :S )

i thought the bloody wiring was gonna test my patience, but this is royally doing my nut in! lmao

 

[Dan@SJM]

do it the other way round, blow down the supply.(with the injectors fitted) if its free flowing your missing the regulator, and ive got one if you need it.

 

[geesus69]

do it the other way round, blow down the supply.(with the injectors fitted) if its free flowing your missing the regulator, and ive got one if you need it.

will do, cheers dan (again) i think we should cut out the middle man and you come and finish this engine off for me lol

 

[Dan@SJM]

lol, i can do for a small fee.

 

[geesus69]

lol, i can do for a small fee.

depends how small lmao

a bacon butty and as many brews as you can drink? :rasp:

 

[Dan@SJM]

LOL, well it'd cost me a bit to drive up there!

 

[geesus69]

LOL, well it'd cost me a bit to drive up there!

im gonna persevere (sp?) for now, but if i get royally stuck then i may be enlisting your help

 

[Dan@SJM]

lol fair enough mate, youve got my number yea? feel free to give me a ring.

 

[geesus69]

no i dont think i have mate

pm me it and i can annoy you by phone aswell as on here :evil:

all was going great while the nights were light and the weather was ok, now its getting dark at 4 and pi$$ing it down its cheesing me off lol