Fuel pressure question

07-26-2005, 05:01 PM

Does anyone konw what stock fuel pressure should be on the MKIII? I just upgraded my fuel sytem with a 2JZ fuel pump a mechanical fuel press. gauge and bosh ajustable regulator. The Toyota repair says stock preesure should be 30-40 psi. Is that at idea or under boost. Any info will greatly help.

suprra_girl · 07-27-2005, 01:55 PM

yep the stock fuel pressure should be 35-40psi... this is at idle.. under boost it should rise...

also please don't double post, it won't get your questions answered any faster

GL

07-27-2005, 04:47 PM

Thanks for the info it hepled out alot. Sorry about the double post, did it on accedent. Also how much should i I raise fuel pressure? I am runing 11psi of boost and still have the stock 440cc injectors.

suprra_girl · 07-28-2005, 01:53 PM

well... really at those levels the stock ecu should be able to still control it just fine

take it for a boost and see what the fuel pressure gets up to and if it holds

i think under boost she'll go to 50ish psi?? not overly sure on a stockish engine

07-28-2005, 05:16 PM

Thanx everyone I found the problem. I set fuel pressure with the vacum line hooked up and that caused fuel pressure for sky rocket under boost ( 80psi). Fuel pressure holds right at 45psi under boost. Now I have enough fuel to feed the fire, at least untill I get a HKS FCD. 15 psi here I come.
P.S. the car is getting really quick. 265hp @ 9psi & 260 torque. Not bad for a lightly BPUed MKIII.

suprra_girl · 07-29-2005, 01:37 PM

congratulations on the #'s

but do be careful... do you have a wideband 02?

to be honest i don't know what your fuel pressure should be under boost...

maybe you should get it dyno'd to ensure you are getting correct fueling.... the last thing i would want is for your engine to detonate

can anyone else chime in on fp?

08-10-2005, 09:53 PM

No I dont have a wideband O2. I do work for a tuning shop with a dyno and a wideband and can use it when ever I want to. On my last runs @9 psi I saw 12.8 to 1 air fuel ratio. Almost on the lean side, that is my I felt I needed a bump in fuel pressure 45psi. I haven't had the chance to get the dyno since the fuel increase, but look for more threads on this in the near future.

08-10-2005, 09:55 PM

Also 45 psi is fuel pressure under boost, at idle I have 35 psi. Wideband monitoring is need though to keep an eye on things.

djalkyd · 03-18-2006, 04:59 AM

any updates on this? i am interested in your outcome because i just upgraded to a walboro 255 fuel pump and i checked mine at idle and i got 34 at idle with the vacuum line on and 38 with it off. pretty close to what the manual says.

i haven't checked it under boost yet so i am wanting to see what an average out come under boost would be.

07-27-2005, 01:55 PM	#2
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	yep the stock fuel pressure should be 35-40psi... this is at idle.. under boost it should rise... also please don't double post, it won't get your questions answered any faster GL __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

07-28-2005, 01:53 PM	#4
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	well... really at those levels the stock ecu should be able to still control it just fine take it for a boost and see what the fuel pressure gets up to and if it holds i think under boost she'll go to 50ish psi?? not overly sure on a stockish engine __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

07-29-2005, 01:37 PM	#6
suprra_girl 7M POWAH! ;) Join Date: Jun 2004 Location: New Zealand Posts: 2,312	congratulations on the #'s but do be careful... do you have a wideband 02? to be honest i don't know what your fuel pressure should be under boost... maybe you should get it dyno'd to ensure you are getting correct fueling.... the last thing i would want is for your engine to detonate can anyone else chime in on fp? __________________ Please use the forum to ask your questions as they will get replied to much faster than pming me Pics of my build. "Good girls are just bad girls that don't get caught" Do a diagnostic first!

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07-26-2005, 05:01 PM	#1
intenseneal Guest Posts: n/a	Does anyone konw what stock fuel pressure should be on the MKIII? I just upgraded my fuel sytem with a 2JZ fuel pump a mechanical fuel press. gauge and bosh ajustable regulator. The Toyota repair says stock preesure should be 30-40 psi. Is that at idea or under boost. Any info will greatly help.

07-27-2005, 04:47 PM	#3
Intenseneal Guest Posts: n/a	Thanks for the info it hepled out alot. Sorry about the double post, did it on accedent. Also how much should i I raise fuel pressure? I am runing 11psi of boost and still have the stock 440cc injectors.

07-28-2005, 05:16 PM	#5
Guest Guest Posts: n/a	Thanx everyone I found the problem. I set fuel pressure with the vacum line hooked up and that caused fuel pressure for sky rocket under boost ( 80psi). Fuel pressure holds right at 45psi under boost. Now I have enough fuel to feed the fire, at least untill I get a HKS FCD. 15 psi here I come. P.S. the car is getting really quick. 265hp @ 9psi & 260 torque. Not bad for a lightly BPUed MKIII.

08-10-2005, 09:53 PM	#7
Intenseneal Guest Posts: n/a	No I dont have a wideband O2. I do work for a tuning shop with a dyno and a wideband and can use it when ever I want to. On my last runs @9 psi I saw 12.8 to 1 air fuel ratio. Almost on the lean side, that is my I felt I needed a bump in fuel pressure 45psi. I haven't had the chance to get the dyno since the fuel increase, but look for more threads on this in the near future.

08-10-2005, 09:55 PM	#8
Intnenseneal Guest Posts: n/a	Also 45 psi is fuel pressure under boost, at idle I have 35 psi. Wideband monitoring is need though to keep an eye on things.

03-18-2006, 04:59 AM	#9
djalkyd 3" Exhaust Join Date: Jan 2006 Location: sacramento ca. Posts: 55	any updates on this? i am interested in your outcome because i just upgraded to a walboro 255 fuel pump and i checked mine at idle and i got 34 at idle with the vacuum line on and 38 with it off. pretty close to what the manual says. i haven't checked it under boost yet so i am wanting to see what an average out come under boost would be.