Fuel pressure at 80psi???

BLK FC3S · 07-13-2008, 06:41 PM

Ok, I hooked up a FPR and a fuel gauge today and thought it was weird/wrong for the gauge to read 80psi. 60ish when the car isnt running, 80 when it's running. I took the FPR apart before installing it to see how one works, I wonder if I didn't put it back together right? What else could make the gauge read so high?

vex · 07-13-2008, 06:56 PM

Need more details. Mechanical or Electronic?

BLK FC3S · 07-13-2008, 08:14 PM

mechanical gauge located after fuel filter, FPR located before return line. I think I'm going to disconnect the FPR and leave the gauge hooked up and see what it reads then.
Its an old filter, I wonder if a clogged filter would give me that high of a pressure?

Fuel setup
Supra fuel pump
550 primes, 1600 seconds
autometer ultralight mech gauge
FPR is unknown, ima post a pic of it and see if someone knows who makes it.

edit pictures:

BLK FC3S · 07-13-2008, 08:22 PM

quick diagram...

vex · 07-13-2008, 08:55 PM

Do you know the stats on the pump?

The reason I ask is that you have alot of unknowns in your fuel system. is your FPR rising rate? Was it hooked up? I think you might be pushing up a lot of pressure from the pump and the FPR is too high. Fuel system should be around 43.5 psi or so I believe (any one validate?).

J-Rat · 07-14-2008, 01:29 AM

Unknown FPR would cause unknown pressure rates. Have you tried adjusting it?

BLK FC3S · 07-14-2008, 04:02 AM

yes, adjusting it didn't effect the pressure??? I'm starting to think I didn't put it back together right.

BLK FC3S · 07-14-2008, 04:10 AM

supra pump as tested:
260 lph @ 43 psi; 220 lph @ 58 psi; @ 12 V 1.
290 lph @ 43 psi; 266 lph @ 58 psi @ 13.5 V 2.
290 lph @ 43 psi; 260 lph @ 58 psi; @ 14 V 1.

FPR is rising rate and hooked up.

RETed · 07-14-2008, 07:11 AM

I'm pretty sure that's a RISING RATE FPR...
Those things should NOT be used on a properly set up fuel system.
It should only be used on hack turbo-on-NA on stock ECU's...like those turbo'd Hondas.

If it is a RRFPR, it's not surprising to see 80psi.
I've seen ratios as high as 12:1.

Throw that thing away, and get a proper boost-dependent FPR which is a 1:1 ratio.
I prefer SX FPR's myself.

-Ted

BLK FC3S · 07-14-2008, 10:58 AM

Oh, it's like one of those vortec FPR's w/ the 12:1 ratio. That makes sense. They look similar too. It was on the car when I bought it with the 13bt and I never knew if it was good or not, figured I'd try it. Thanks Ted.

SX > Aeromotive? I only see them with AN fittings. How can I connect a normal line to the FPR without going all out and re-plumb my whole fuel system?

BLK FC3S · 07-14-2008, 08:11 PM

ok.......
bought this...

installed...

no change.....

ideas?

BLK FC3S · 07-14-2008, 09:12 PM

ok, moved the gauge to the port on the FPR and it dropped to 25psi, adjusted it back up to 40psi at idle for right now. Don't know why the pressure is different from the feed to the return line but I guess it is.

Anyways, that problem solved.

NOW, my connector going to the fuel pump is melting. I guess mazda didn't intend for it to carry that many amps to a pump. Talking about the white 4 prong connector on top of the fuel tank.
Any ideas on how I can run a new connector to the fuel pump and sender and keep it air tight? What have you guys done?

RETed · 07-15-2008, 02:27 PM

Wow, that's really interesting!
I never though the FPR inlet would be that high versus the dedicated pressure port on the FPR itself.
I gotta test that out myself one day...

To redo the wiring, you really need to use the proper parts.
Since we're talking about electricity + gasoline, bulkhead fitting + proper wire insulation is the key.

BTW, what kinda fuel pump are you running?

-Ted

BLK FC3S · 07-17-2008, 06:46 PM

^ supra tt fuel pump (heard it outflows the walbro at 14v) wired to run 14v constantly.
It is intank using stock location and plumbing so bulkhead fitting not needed. I haven't done it yet, but if I pull off that white connector on top of the fuel tank, what can I replace the hole with as far as a new connector that will hold pressure. I assume a rubber gommet is out the window. I can't be the only one to melt one of these connectors and have to replace it.

07-13-2008, 06:41 PM	#1
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	Fuel pressure at 80psi??? Ok, I hooked up a FPR and a fuel gauge today and thought it was weird/wrong for the gauge to read 80psi. 60ish when the car isnt running, 80 when it's running. I took the FPR apart before installing it to see how one works, I wonder if I didn't put it back together right? What else could make the gauge read so high? __________________

07-13-2008, 06:56 PM	#2
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. Posts: 2,113 Rep Power: 19	Need more details. Mechanical or Electronic? __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group

07-13-2008, 08:14 PM	#3
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	mechanical gauge located after fuel filter, FPR located before return line. I think I'm going to disconnect the FPR and leave the gauge hooked up and see what it reads then. Its an old filter, I wonder if a clogged filter would give me that high of a pressure? Fuel setup Supra fuel pump 550 primes, 1600 seconds autometer ultralight mech gauge FPR is unknown, ima post a pic of it and see if someone knows who makes it. edit pictures: __________________ Last edited by BLK FC3S; 07-13-2008 at 08:29 PM.

07-13-2008, 08:22 PM	#4
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	quick diagram... __________________

07-13-2008, 08:55 PM	#5
vex RCC Loves Me Not You Join Date: Jul 2008 Location: Influx. Posts: 2,113 Rep Power: 19	Do you know the stats on the pump? The reason I ask is that you have alot of unknowns in your fuel system. is your FPR rising rate? Was it hooked up? I think you might be pushing up a lot of pressure from the pump and the FPR is too high. Fuel system should be around 43.5 psi or so I believe (any one validate?). __________________ The Official FC Radiator Thread My Project Thread: Cerberus CCVT Virginia Rotary Group Last edited by vex; 07-13-2008 at 09:13 PM.

07-14-2008, 01:29 AM	#6
J-Rat Rotary Fan in Training Join Date: Mar 2008 Posts: 59 Rep Power: 18	Unknown FPR would cause unknown pressure rates. Have you tried adjusting it? __________________ 1988 10th Anniversary 554 RWHP, 395 RW Torque 10.7 @ 126! owner: www.azrx7.com Engine built by ARIZONA ROTARY ROCKETS www.azrotaryrockets.com

07-14-2008, 04:02 AM	#7
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	yes, adjusting it didn't effect the pressure??? I'm starting to think I didn't put it back together right. __________________

07-14-2008, 04:10 AM	#8
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	supra pump as tested: 260 lph @ 43 psi; 220 lph @ 58 psi; @ 12 V 1. 290 lph @ 43 psi; 266 lph @ 58 psi @ 13.5 V 2. 290 lph @ 43 psi; 260 lph @ 58 psi; @ 14 V 1. FPR is rising rate and hooked up. __________________

07-14-2008, 10:58 AM	#10
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	Oh, it's like one of those vortec FPR's w/ the 12:1 ratio. That makes sense. They look similar too. It was on the car when I bought it with the 13bt and I never knew if it was good or not, figured I'd try it. Thanks Ted. SX > Aeromotive? I only see them with AN fittings. How can I connect a normal line to the FPR without going all out and re-plumb my whole fuel system? __________________

07-14-2008, 08:11 PM	#11
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	ok....... bought this... installed... no change..... ideas? __________________

07-14-2008, 09:12 PM	#12
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	ok, moved the gauge to the port on the FPR and it dropped to 25psi, adjusted it back up to 40psi at idle for right now. Don't know why the pressure is different from the feed to the return line but I guess it is. Anyways, that problem solved. NOW, my connector going to the fuel pump is melting. I guess mazda didn't intend for it to carry that many amps to a pump. Talking about the white 4 prong connector on top of the fuel tank. Any ideas on how I can run a new connector to the fuel pump and sender and keep it air tight? What have you guys done? __________________ Last edited by BLK FC3S; 07-14-2008 at 09:19 PM.

07-17-2008, 06:46 PM	#14
BLK FC3S C088 Join Date: Mar 2008 Location: Mount Dora, FL (no its not a mountian) Posts: 112 Rep Power: 18	^ supra tt fuel pump (heard it outflows the walbro at 14v) wired to run 14v constantly. It is intank using stock location and plumbing so bulkhead fitting not needed. I haven't done it yet, but if I pull off that white connector on top of the fuel tank, what can I replace the hole with as far as a new connector that will hold pressure. I assume a rubber gommet is out the window. I can't be the only one to melt one of these connectors and have to replace it. __________________