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Old 02-13-2019, 01:10 PM   #1
TXwrxWagon
Scooby Specialist
 
Member#: 191557
Join Date: Oct 2008
Chapter/Region: TXIC
Location: Rockwall-East DFW
Vehicle:
2004 WRX Wagon
WRB not so minty fresh

Default Parallel Fuel systems: what is your idle PSI and what does it drop too?

Ok,

I had 2 fairly significant leaks at the brazed connections of the OE metal lines under my intake. So, since I am doing upgrades this year anyway, I figured if I am spending $$ on fuel replacement parts, I'd do Parallel set up.

Please don't chime in "what's your goal?" "You don't need that stock lines are good to 400whp" etc. I know. and thanks.

I did this for 2 main reasons:

1, I was spending $150-200 to do OE crap anyway, so why not spend another 25% and do it once and if my stroker or 2.5 hybrid happens, I am totally ready

2. I am about to do injectors, VF48, and bacsically stage 2-3+ before end of spring. so replacing the injectors will be a snap after all this was done.

Bonus reason: yeah it looks cool. shoot me.

Anyway. I'd like to know:

1. what idle psi's everyone is seeing (yes I know should be 34-38psi with vac and 42-46psi with it off) I want to know what people are really seeing.

2. more importantly: if you start the car and let it idle, then shut off the car, to what psi does your gauge show and how quickly does it bleed off?

I have a mechanical fuel psi gauge on my return distribution block and its showing proper idle psi (36-38psi) and when I turn the key off, it immediately starts to slowly drop off and rest at almost exactly 22psi.

I'm using the OE FPR on my return distribuation block.

Car is running great. I'm just curious now that I can have a visual of what is happening, if anyone else can share what they are seeing.

Thanks

~Rob
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Old 02-13-2019, 04:23 PM   #2
rtv900
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Member#: 428511
Join Date: Aug 2015
Location: philadelphia
Vehicle:
2016 STI

Default

if somebody sees a lower drop or a different hold point or no hold point at all what exactly are you going to do next?
Try and match it?

Your numbers are fine and any pressurized system is going to bleed down at some rate, so who really cares if it bleeds down when it's off?
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Old 02-13-2019, 09:19 PM   #3
TXwrxWagon
Scooby Specialist
 
Member#: 191557
Join Date: Oct 2008
Chapter/Region: TXIC
Location: Rockwall-East DFW
Vehicle:
2004 WRX Wagon
WRB not so minty fresh

Default

well.. yeah not exactly... it DOES matter... to me, LOL

Here is the back story.

I got everything installed and pressurized the system for the first time. Took 2 cycles of the key, wasn't trying to start it. This was 10pm on Last Tuesday. I didn't make it back over to the shop where the car was until almost 24 hours later. system was still holding 35-36 psi so, minimal drop.

I did the rest of my work and buttoned up everything. Went back to the hotel. Following night, still holding over 30psi. I finally try to start it, had missed a couple grounds, finally got it started and it ran chuggy and all wrong. Turned out I had a coil pack loose. Not before I thought maybe I had a feed/return flipped, so undid 1 return line. Found the coil, hooked everything up, and after that line was removed and resinstalled, the system would only maintain pressure while running. Shut if off, it would drop immediately to zero. Car ran ok, but was obviously struggling for fuel.

Finally found a connection that was 3/8" NPT on the return distribution block where the Radium adapter to the OE FPR goes was leaking vapor. Not even enough to leak liquid fuel, but allowing pressure bleed off.

Now the final pressures above. I'm just curious as to why before it maintained pressure for nearly 2 days, now not so much. It will drop to 30-ish psi in 15 minutes.

So all that said, car runs great. Just curious what others are seeing. or if I need to be digging for another vapor leak.

~Rob
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