H4Inf

Basically my fuel flows like this:

Fuel Tank -> Prepump -> Surge Tank -> EFI Pump -> Secondary Rail -> Pressure Regulator -> Primary Rail -> Pressure Regulator -> Overflow line returns to Surge Tank. (Surge tank overflow returns to the fuel tank).

I'm wondering if anyone can figure out why it's been setup like this. I thought the fuel was meant to go thru a Pulsation Dampener, then primary rail, then secondary rail then pressure regulator.

Cheers,

H4Inf

BUMP


heres a picture that may help those finding it difficult to understand from my description.

I'm just wondering if anyone knows why there are 2 pressure regulators, and the pro's and con's of this setup?

Thanks!!

SS124A

in this application you would need 2, because each are at the end of 2 rails...
if you think about it, you have fuel exiting the secondary rail first, so it must be regulated at the end before going to the next one. IF the pressure going into either rail is too high, the regulator(s) can "bleed" and excess through the system, back to the tank. (this would be something you would expect at idle to 3800 rpm on a stock FC set-up.... the RPM would vary in this application based on how the fuel map is set.... assuming this is on a standalone) IF the pressue is too low, the FPR(s) will "clamp" pressure within the rail to assure there is enough volume/pressure for the injectors to pulse, again based on their settings...

I don't know why they plumbed them in series like that, unless the second rail can operate at a lower volume than the first. which makes sence I guess, because the seconadary injectors should flow more, therefore they should be first on the food chain.

82streetracer

iTrader: (1)

your pressure regulator setup is a bit funky, I would switch it to a parrallel system.

the rest looks great though

H4Inf

Thanks for the description SS124A, I might have a go at hosing it up in parallel (because I'm having a problem where I think my primaries are not getting enough fuel) - described below:

This problem is on and off. Basically what happens is it feels like the car accelerates slower, and in the primary section of the accelerator (primary butterflies opening only), with any load on the engine, it doesnt respond at all. Say I have clutch in and push on accel slowly taking it up, the engine revs slowly go up, but if I say take the revs up to 2500 (below the secondary injectors threshold) and let the clutch out, the engine suddenly drops revs and it stalls if I don't push the clutch in again. If I'm over about 3000 (secondaries threshold) when I let the clutch out, its ok and keeps going fine. I experience these problems to varying degrees at different times.

Its night, I'm driving with the lights on. Push on the accelerator and it doesnt accelerate as fast as usual, and its a bit jumpy bringing the revs up. Once the revs get past about 3000, it runs a lot smoother. I pretty much have to have the accelerator to the point where the secondary butterflies start to open for the car to actually respond.
eg. Cruising at 60km/h with foot on the accelerator a bit. Say I lift off, it decelerates a little, but when i push it back on (just a little) it backfires then the revs pickup, but slower than usual. Sluggish.

Any ideas would be great guys, cheers!

jasrx

it is tuned right.? because to me it sounds more like a tuning issue [ either too rich or too lean] where in melbourne are u .? if u have msn my username is jasrsjasrx@hotmail.com

H4Inf

That's a big ask. I don't believe it's tuned even close to perfect, but this problem often happens to varying degrees... quite intermittent... so I'm not sure its entirely tuning.

Just to elaborate a bit.

Thinking back, say I'm decelerating, then want to accelerate, I push my foot down on the pedal (opening primary butterflies alone), then just as the secondaries start to open and it backfires, the TPS reaches it's end.

Perhaps my ECU is setup to tell the secondary injectors to start injecting when the TPS hits the end? Problem is I can't check. I'd need a very old microtech handset. Local rotary place can't even get anything out of it.

H4Inf

As well as my fuel setup, I think my fuel pump isnt getting enough power at all times.

On quite hot days i'm guessing the alternator isn't running as efficiently as usual, and not providing as much current as usual, and at night when I have the lights on, they are drawing a lot.

I think rewiring the fuel pump with decent copper direct from the battery, and clean up all the connections in between will help when the lights are on, because the headlights draw so much current that the fuel pressure seems to drop and the primary rail empties and refills causing the revs to jump up and down, backfiring, back up and down... unless the secondary injectors are active.

So I'm going to rewire the fuel pump when I next get the chance, probably in a few weeks, might get new hose and rehose everything, get a little plug for the end of the secondary rail so I can hook it directly to the primary rail instead of going through a regulator first, and may have to look at the regulator in the alternator, as it doesnt seem to be charging as well as it should.

I'll let you all know how it goes, in the meantime if you have any thoughts, let me know cheers.