stu21t

just had my car on the rollers and its not getting enough fuel,
it makes 3.5bar ish fuel pressure at idle
but it doesnt rise with the boost

ian recons the pump isnt up to it but its a new 044.

spec is
044 pump with -10 inlet
sytec bullet high flow fuel filter
-6 hose and fittings throughout
4x4 fuel regulator adapted to -6 outlet
all new and with new wiring

the regulator is working as it drops when you disconnect the vacuum hose and does rise a little when it starts to make boost but then doesnt get higher when it makes more boost.

surely all this would be able to make over 3.5bar and flow for more than 400bhp shouldnt it?

any1 got any ideas?

or is it more bad luck, and i need a bigger pump and run 2 filters just to be sure.?

andy escos

iTrader: (1)

have you put a volt meter on the fuel pump when the car is running to see if you have minimum 12v but could be upto 14.5 volts you might have a dodgy alternator.make sure your pump has a good earth cos your 044 pump iswell up for 500+ hp

stu21t

i havent yet, only just got home, im going to check that tomorow.
but, alternator is new, battery is new and fully charged, wiring is all new.

thats what makes it hard to find the fault. lol

JTECH James

iTrader: (13)

could still be a faulty reg imo, can you simulate boost somehow on the vac pipe, and see if you can get it to rise 1:1?

Stu @ M Developments

iTrader: (12)

What you need to do here is load the engine up at low rpm with a fuel pressure gauge plumbed into the car and check that the fuel pressure rises linear with the boost in at least a 1:1 ratio Stu.

Alternatively, bridge the fuel pump relay and connect a bike pump to the top of the reg, teed into a boost gauge and do it that way. That way would technically be a better test as it would not use any fuel, so if it doesn't drop on that test then the problem is the fuel volume, not pressure.

stu21t

im more inclined to think its the regulator but that would be a real pain to change because its a 4x4 rail so the regulator is bolted directed to the rail so without changing to a 2wd reg that wont bolt to the 4x4 plenum cover, and then id need to get another fuel rail with -6 threaded ends on it.


cheers stu, thats a big help,
if i do this on idle with the pump constantly running and i get an extra bar of fuel pressure with a bar of boost then that means the regulator is working but the pump cant keep up at higher revs when it needs more flow, not presssure?

if i pump it up with a bike pump will it hold the boost? i wont be pumping into thin air lol

luckily a mate has a brand new 044 that i can try so will get that off him.
i might end up fitting both and 2 filters if i cant get it to work as is. it should tho.

cheers

GARETH T

you shouldnt need to go through the expense of fitting another pump and filter
your options are
filter blocked
pump not producing the flow rate (either fucked or low voltage)
a blockage or narrowing of your supply fuel cross sectional area (bent pipe or the like)
regulator fucked
air leak to regulator
i think thats about it off the top of my head

stu21t

i checked the filer on the dyno, it can be taken apart, its got a metal high flow element, and that was spotless.
going to check the pump and voltage this afternoon but they are both new so should be fine but obviously doesnt mean its ok.
all pipes are new -6 braided and they all look fine.
regulator was run on the dyno and didnt show any probs, but could b at fault. and dont think theres an air leak but will double check.

hopefully i can sort it soon and get back on the rollers.

stu21t

i think ive found the problem.

did as stu said and got a bicycle pump connected to my boost gauge and the fuel pressure regulator, and before i even started the engine i tried to pump it up to see if it held pressure

it didnt

so i disconnected the hose of the regulator and blocked it to see if the lead was to do with the boost gauge, and it held pressure, connected it back into the fuel pressure regulator and it didnt hold.
turns out the bleed nipple on the top of the fpr is loose and leaking boost
i just pulled it out by hand.

it looks like its supposed to be glued in place so im going to carefully araldite it back in tonight and try it again tomorow.

cheers peeps, big help.

Stu @ M Developments

iTrader: (12)

A very common engine destroyer. Well found.

Anyone interested in why this affects fuelling on boost can read all about it here:

stu21t

couldnt have done it without your help m8
very much appreciated.

stu21t

update
right still not fixed lol.

the vacuum hose nipple is now fixed but i still have a leak
the air is now bleeding out from where the allen key grub screw is.
if i put my finger over the end of the hole the air cant escape but remove my finger and the air escapes and it doesnt hold boost.

question is can i fix it?
i can put a short M8 bolt into the top of it with a bit of thread sealer on it and it wont effect the pressure but will seal in the boost.
BUT
will the fact the air gets past the grub screw effect the working of the regulator?

Stu @ M Developments

iTrader: (12)

Your risking your engine with such repairs mate, its time to fit a new one im afraid.

stu21t

not a problem, dont mind fitting a new on if it cant be repaired
can you get a 4x4 regulator with a -6 fitting on the bottom for the fuel pipe?
can a std 1 be modded to carry a -6 fuel return?
or has any1 got 1?
cheers

cozmeister

iTrader: (1)

Only if you have very good eyesight

Think I'll go and check my regulator too now! Or does this only apply to 4x4 regulators?

stu21t

applies to all regulators m8.

GARETH T

i made a fitting years ago, so i could run any regulator with a 4x4 rail!

but this is nothing wrong with a 4x4 reg anyway,, so its not point in buying a posh one