PETERPOOP's Turbo Build Thread. - Page 5 - Toyota Yaris Forums

rob323 · 12-12-2010, 04:06 PM

The injectors could quite well be getting max'd out cause the fuel pressure system has no reference to manifold pressure in a stock (return-less) fuel system. If you can raise the fuel pressure as boost increases, it would give you substantial headroom in that side of things. The other problem is that the injectors may not be spraying optimally when having to fight against the boost pressure in the manifold.

Bluevitz-rs · 12-12-2010, 05:08 PM

I just thought of another problem you guys might be having with tunning... the stock fuel pump is a 2 speed unit. I forget exactly how it operates, but it goes something like, "low speed at idle and cruse" and "high speed under acceleration".

If someone has a repair manual, they should be able to confirm this. Because this could be causing the fuel pressure to jump around

cali yaris · 12-12-2010, 08:24 PM

Has anyone else had trouble with fuel pressure or the pump at low boost? Seems like everyone would, or no one would.

rob323 · 12-12-2010, 10:06 PM

But has anyone with a stock system monitored the fuel pressure while under boost? no point having 40 psi of fuel pressure at idle if the injectors are just dribbling fuel out when under boost even when at 100% duty cycle.

I don't know over there, but the one Aussie Yaris pump I have pulled out was about the same size as a D cell battery. The pump in the Echo is almost twice the size in comparison.

cali yaris · 12-13-2010, 10:09 AM

I had 100% stock fuel system at 8 psi. With larger injectors.

I still don't understand why only one person would experience the problem, nor did you explain that point, since you say injectors can't be his problem.

Your experience is helpful -- Just quoting a pressure number doesn't help me understand.

Quote:

Like Rob said before me, not one person here is monitoring fuel pressure.

I am now, but I don't think that's what you guys meant.

cali yaris · 12-13-2010, 02:50 PM

It's not that difficult to upgrade to a Walbro 255. Can you do that without a return line?

The stock fuel pump is the size of a "D" cell battery, LOL. I posted a pic somewhere of it!

PETERPOOP · 12-14-2010, 10:26 PM

greddy emanage ultimate. Still trying to talk to the tuner about all of this...

PETERPOOP · 12-15-2010, 12:09 AM

Ok. Well I talked vaguely to the tuner via email and he suggested the walbro 255. however, i don't know if he is putting much thought into it or not whether i need to run a return fuel line or not. i mentioned it to him, but he didn't address it via email.

Question. Would the tuner be able to successfully tune with the walbro 255/larger injectors in place, and no return system?

Wondering if i should just try the larger injectors first, and see if that fixes the problem. Then if not, get a larger fuel pump and go from there.

I'll be going with the spec stage 2+ clutch and flywheel; also a Kaaz LSD.

cali yaris · 12-15-2010, 01:38 AM

injectors go on in minutes, you'll know if you're on the right track. Installing and running a fuel pump and especially a return line is a pain in the butt.

cali yaris · 12-15-2010, 12:14 PM

Quote:

Another option is to lower the boost which will in turn require less fuel demand.

How dare you give him these silly ideas? That is not an option!

PETERPOOP · 02-08-2011, 10:21 PM

Just put in a Spec stage 2+ clutch, Spec lightened flywheel, and Kaaz LSD. Feels gooooood.

ps: Sorry tamango.

Focus_Sh1ft · 12-13-2010, 01:50 PM

I really think it's the fuel pump as well, but I can't offer any explanation as to why. Wouldn't all the blitz people experience similar problems?

The injectors maxing out just doesn't make sense though. 1ZZ should easily cover 8 psi of boost...

What's the life expectancy on a fuel pump? Maybe Peter's is on its last legs?

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12-12-2010, 04:06 PM	#1
rob323 Don't drive it, RALLY it! Drives: 1999 echo PRC rally car Join Date: Oct 2008 Location: Joyner, Brisbane Posts: 321	The injectors could quite well be getting max'd out cause the fuel pressure system has no reference to manifold pressure in a stock (return-less) fuel system. If you can raise the fuel pressure as boost increases, it would give you substantial headroom in that side of things. The other problem is that the injectors may not be spraying optimally when having to fight against the boost pressure in the manifold.

12-12-2010, 05:08 PM	#2
Bluevitz-rs 1NZ-6spd View User's Garage Drives: '05 6-Spd Vitz RS Join Date: Oct 2008 Location: Oshawa, Ontario, Canada Posts: 2,967	I just thought of another problem you guys might be having with tunning... the stock fuel pump is a 2 speed unit. I forget exactly how it operates, but it goes something like, "low speed at idle and cruse" and "high speed under acceleration". If someone has a repair manual, they should be able to confirm this. Because this could be causing the fuel pressure to jump around

12-12-2010, 08:24 PM	#3
cali yaris ULTIMATE View User's Garage Drives: 07 Yaris Turbo Join Date: May 2007 Location: Canoga Park, CA Posts: 14,857	Has anyone else had trouble with fuel pressure or the pump at low boost? Seems like everyone would, or no one would.

12-12-2010, 10:06 PM	#4
rob323 Don't drive it, RALLY it! Drives: 1999 echo PRC rally car Join Date: Oct 2008 Location: Joyner, Brisbane Posts: 321	But has anyone with a stock system monitored the fuel pressure while under boost? no point having 40 psi of fuel pressure at idle if the injectors are just dribbling fuel out when under boost even when at 100% duty cycle. I don't know over there, but the one Aussie Yaris pump I have pulled out was about the same size as a D cell battery. The pump in the Echo is almost twice the size in comparison.

12-13-2010, 02:50 PM	#6
cali yaris ULTIMATE View User's Garage Drives: 07 Yaris Turbo Join Date: May 2007 Location: Canoga Park, CA Posts: 14,857	It's not that difficult to upgrade to a Walbro 255. Can you do that without a return line? The stock fuel pump is the size of a "D" cell battery, LOL. I posted a pic somewhere of it!

12-14-2010, 10:26 PM	#7
PETERPOOP View User's Garage Drives: 08 white liftback Join Date: Oct 2008 Location: Oahu Posts: 3,674	greddy emanage ultimate. Still trying to talk to the tuner about all of this...

12-15-2010, 12:09 AM	#8
PETERPOOP View User's Garage Drives: 08 white liftback Join Date: Oct 2008 Location: Oahu Posts: 3,674	Ok. Well I talked vaguely to the tuner via email and he suggested the walbro 255. however, i don't know if he is putting much thought into it or not whether i need to run a return fuel line or not. i mentioned it to him, but he didn't address it via email. Question. Would the tuner be able to successfully tune with the walbro 255/larger injectors in place, and no return system? Wondering if i should just try the larger injectors first, and see if that fixes the problem. Then if not, get a larger fuel pump and go from there. I'll be going with the spec stage 2+ clutch and flywheel; also a Kaaz LSD.

12-15-2010, 01:38 AM	#9
cali yaris ULTIMATE View User's Garage Drives: 07 Yaris Turbo Join Date: May 2007 Location: Canoga Park, CA Posts: 14,857	injectors go on in minutes, you'll know if you're on the right track. Installing and running a fuel pump and especially a return line is a pain in the butt.

02-08-2011, 10:21 PM	#11
PETERPOOP View User's Garage Drives: 08 white liftback Join Date: Oct 2008 Location: Oahu Posts: 3,674	Just put in a Spec stage 2+ clutch, Spec lightened flywheel, and Kaaz LSD. Feels gooooood. ps: Sorry tamango.

12-13-2010, 01:50 PM	#12
Focus_Sh1ft Drives: 08 Yaris Turbo; 06 tC Turbo Join Date: Jan 2010 Location: New Jersey Posts: 875	I really think it's the fuel pump as well, but I can't offer any explanation as to why. Wouldn't all the blitz people experience similar problems? The injectors maxing out just doesn't make sense though. 1ZZ should easily cover 8 psi of boost... What's the life expectancy on a fuel pump? Maybe Peter's is on its last legs?