using a stock & adjustable fuel press reg in series? Confusing results are now in...

[Wildsupra]

hahahha

ok.. idle is 40psi - manifold pressure = less than 40... for a start.
say you have 50kpa manifold pressure at idle.. thats about 7psi-ish.. so stock pressure is what? 33psi? 50psi is 17 up on that.. so at 15psi, you are running 40+15+17... = 72.. = danger territory for fuel pump duh...
you could adjust it up say.. 5psi at a time.. and see if you get a peak (trough) in the AFR's.. if you do, then you are killing the pump.

maybe you are adjusting it backwards?

what size are your injectors? how many of them? what is duty cycle at full noise.
which fuel pump? 315 or 341?

oh.. what fuel pressure reg is it? malpassi? is it rising rate? or 1:1?
gto any misfiring or poor combustion to affect the AFR's?

more info needed


ps, if it is a Malpassi, you have got the best results you can hope for

Ok so what base fuel pressure would you expect it to run at idle with vacuum line connected? about 33psi?

By the sounds of it i prolly did up pressure too much and max out the pump or something like that, for some reason i had ~42psi base rate in my head as stock, maybe thats about right with vac line disconnected?!?

Definantly not adjusting it backwards because i also installed a gauge directly to the new adj reg, i can see it go up and down as i go, and even if i was it shouldnt get leaner than the stock reg would allow. (if i was lowering the fuel press in the adj reg that is)

The reg is a sard 1:1 probably should have gone a rising rate but oh well. Thats why im limited to adjusting base pressures, its obviously gunna get rich down low once its working properly, but im willing to live with that.

Its not missing or anything on full noise, or at all for that matter, runs sweet as.

Injectors are stock 1j injectors 390cc or something? 6 of em and not sure which model walbro pump it is. EDIT: i think its the 341. As for duty cycle im assuming they are pretty dam close to 100% but thats also another thing im trying to find out by upping the boost a little at a time to see where the ratio's get crazy. that should pin point max boost i can run on the mines ecu.

[Wildsupra]

ok took the car for another run. Geeze its good being the only person on the road at this time of night.
This time i left home with a base pressure of 25psi (which surely must be lower than stock, so shouldnt have any effects yet)
Then i ran the car and pulled over a number of times upping the press by 2 psi at a time, it appears to be having no effect whatsoever on the ratios until i get up to pressures around the 46psi where it starts to lean out like crazy.
Now im starting to wornder if there is a restriction somewhere else in the fuel system? maybe the fuel filter? I think i'l install a new filter and then go for a few more runs starting from scratch again.
It also seems that anything over ~6psi of boost yields the same afr's which to me would indicate a restriction . Surely at 6psi it shouldnt go anywhere near lean?!?

Matty

[thechuckster]

fwiw: i have a sard, i set the pressure with the engine off - 38psi is my base pressure.

[Wildsupra]

That would be the same as setting it with the vac line disconnected, but yeah i've tried various pressures anyways now, its fuel filterreplacement time.

Matty

[The Real Roadrunner]

pics? sure you didnt install it in the feed line? coz there the symptoms your discribing and yes ive seen it b4.

always set the pressure on prime not with the engine running id shoot for 45psi base and the highest i would go is 55psi depending on the injector and pump/s

cheers
linden

[Wildsupra]

cant take photo right now, but this is the reg im using, i ran the fuel in from the rail to the side fitting and the fuel out (return to tank) from the bottom fitting.

[Hibba]

i say ditch the standard reg, just run the sardie by its self. set the pressure at idle with the motor running at 32psi. and bob's ya auntine.