2JZ less power after pump upgrade

[thrashlux]

HI I have a hilux with a 2j and a r150 5 speed
It was running ok for the last 4 weeks I had a tempory fuel tank fitted from a corona that had a 3sfe (import)
it went ok but it seemed to have good punch straight off throttle but then seems to struggle a bit at full power (to be expected for such a pissy fuel pump)

today I commisioned my large fuel tank which runs a 023 intank that sits in a well 150mm deep with 130L of fuel above it

the problem is now it feel like it has got less power at full throttle than with the pissy little one

[LeeRoy]

Perhaps it was leaning out under full throttle and now that you have a pump that can handle the fueling requirements its running richer, and incidently, making less power.

This is only speculation though, and the only way your ever going to really know is if you ran it on a dyno with both pumps (at seperate times of course) and graphed the AFR's.

[lexsmaz]

I would agree with LeeRoy,
I had the same issue with my 1jzgte in my corona, you will need to check fuel pressure's & flows, etc .. i had to cut off & change my fuel pressure regulator, the old one couldn't dump / return enough fuel back ... All ok now though ..
Next time you floor it check your rear vision mirror, with mine you could see shit loads of black smoke even through the mirrors & runing a cat as well .. ( would have been one dirty pussy )

[thrashlux]

thanks guys that confirmed what i thought already its good to hear others have had the same experiences
this is what i will do
I disonnected the battery to reset the computer today went for a half hour drive it may be slightly better or i might be getting used to less power!

tomorrow i will fit a pressure guage to the fuel pressure in the fuel line and do some full power runs with both pumps (one at a time)
I have moved from brisbane and now i live in kiribati near fiji on the equator so there is no dyno but what i do have is a 4km runway that the 737 lands on every tuesday and thursday so i will watch the fuel presure and see how it looks

thanks thrashlux

[thrashlux]

Hi thanks alot for your response about my fueling problems

LEXMAS I was just wondering what brand of fuel pressure reg you put on
and are you running factory computer and injectors?
why I ask is I also have an ra23 with a gen 3 3sgt i put a malpassy on it and it was hard to get right because the rising rate was too high and i ended up having it getting too lean at idle and too fat at full power
it was adding too much presure for the factory computer
Do you know if the standard pressure reg in a 2j is a rising rate or a linear rate which i think is what I should have put in the ra 23

[lexsmaz]

Hi thrashlux,

I am runing standard comp & standard injectors etc ..
i am runing a rising rate malpassi regulator with vacuum line obviously, ( Was advised by a mate that the rising rate was the one to use )... I had the same issues with runing quite low fuel pressure at idle to allow for increased fuel pressure once it came on boost & it still wasn't any good, too much fuel still on boost.. Ended up taking the vacuum line off permanently & increasing the fuel pressure to from memory just slightly above standard spec's & all good now ..
The standard fuel pressure regulator's are sort of a varaible rate regulator, hence the vacuum line on them, but as with most reg's that just increases fuel pressure slightly once vacuum is depleted, but not sure the results once boost is applied though to those 1J & 2J regulators ...
Because i have no vacuum source at all on my regulator now is the reason i cranked up the fuel pressure slightly to represent a load condition ..
It seems a little bit rich at idle, but runs very well though, 199 RWKW at only 10 psi of boost and still gets around 10 liters per 100 km of driving so i am more than happy with the result ...

Hope that helps slightly ..

Rob ..

[thrashlux]

thanks alot for that sorry i spelt your name wrong but i noticed just after i sent it

well i might have an answer for you the way i fixed my ra23 was i put a check valve and a needle valve so that on boost i could bleed off pressure to compensate for the overly excited rising rate hence the correct presure under boost
but under vacume the check valve prevents any loss of vacume allowing a good idle as well
(this is all regarding the sense line)

I just used one of the little check valves from an old engine's vacume plumbing

I got the best of both worlds one adjustment on boost and one off boost

cheers

[thrashlux]

Tomorow i will map the pressure curve of the standard reg in vac and pressure on the bench using a std fuel pump and let you know what i find mabe we dont want rising rate with std computer if so all you have to do is buy a new spring for your reg and you will be apples

cheers

[lexsmaz]

That will be interesting to hear the feedback, especially with positive pressure applied to the reg ...

But i will just keep mine as it is, no biggy & no real drama's now either ..

Thanks ..

Rob ..

[Mos]

i had to cut off & change my fuel pressure regulator, the old one couldn't dump / return enough fuel back

Not sure if you're suggesting that the factory reg doesn't cope, or that your specific reg was faulty?
Factory 1JZ fuel systems are generally two speed, so potentially if you have a pump that flows way more than required it might outflow the reg and return lines at low loads. However, plenty of people run 1JZs with a single speed, upgraded pump without problems and the regs cope fine - it's interesting that you had problems.

i am runing a rising rate malpassi regulator with vacuum line obviously, ( Was advised by a mate that the rising rate was the one to use )...

Rising rate FPR, as far as I understand, is only for situations where you want to increase fuel delivery at higher boost levels with "hydraulic" control.
The "proper" way is with larger injectors and with correct fueling via a correctly tuned ECU. The "dodgy" way is a rising rate FPR and a fuel cut defender, generally on a factory ECU, so the ECU stops increasing pulse width on the injectors (so it doesn't hit boost cut) and your RRFPR supplies the extra fuel required at those boost levels.

I am runing standard comp & standard injectors etc ..
Ended up taking the vacuum line off permanently & increasing the fuel pressure to from memory just slightly above standard spec's & all good now ..

GASP!!! Have you dyno'ed it? I'd be keen to seen the AFRs!

The standard fuel pressure regulator's are sort of a varaible rate regulator, hence the vacuum line on them, but as with most reg's that just increases fuel pressure slightly once vacuum is depleted, but not sure the results once boost is applied though to those 1J & 2J regulators ...

The standard reg is designed to maintain a specified fuel pressure across the injector (around 40psi) - ie linear rate - hence the need for the manifold reference - at 10 PSI manifold pressure the regulator will regulate to the fuel pressure to 50psi above atmospheric, and at max manifold vac the fuel pressure will be around 25psi above atmospheric.

Because i have no vacuum source at all on my regulator now is the reason i cranked up the fuel pressure slightly to represent a load condition ..
It seems a little bit rich at idle, but runs very well though, 199 RWKW at only 10 psi of boost and still gets around 10 liters per 100 km of driving so i am more than happy with the result ...

By disconnecting the manifold reference you have effectively created a regulator with 40psi above atmospheric, meaning you have way too much fuel at idle, and not enough at boost. Unless you have a dyno graph showing "safe" AFRs I would be extremely nervous driving a car like that anywhere near full power...
I'm not sure from your post whether your vac reference is hooked up or not?

well i might have an answer for you the way i fixed my ra23 was i put a check valve and a needle valve so that on boost i could bleed off pressure to compensate for the overly excited rising rate hence the correct presure under boost
but under vacume the check valve prevents any loss of vacume allowing a good idle as well
(this is all regarding the sense line)

A lot of effort to go to fix the selection of component Probably technically more correct than an FCD...

Tomorow i will map the pressure curve of the standard reg in vac and pressure on the bench using a std fuel pump and let you know what i find mabe we dont want rising rate with std computer if so all you have to do is buy a new spring for your reg and you will be apples

Will be interesting to see what you find, because the factory reg *shouldn't* be rising rate. We'll wait and see

A dyno run could give so much information
Given that you have a fuel pressure gauge, have you measured the fuel pressure in the rail at high loads? If it's correct the problem will be elsewhere.

FWIW my 2JZ ran fine on stock boost using a factory MX83 fuel pump with appropriate AFRs depending on setup (with and without cooler).

Mos.

[thrashlux]

Thanks mos that is what i have been warming up to for along time now (that toyotas run linear fuel pressure reg ie 1pound more boost = 1more pound of fuel pressure)
But as you would know there is a lot of miss information floating around
and most performance shops as soon as you mention forced induction and fuel pressure reg they say "oh you need a rissing rate"
but this is not the case at all when running std computers and injectors
without fuel cut defenders

I am running a bosch 023 it is a 600 hp in tank pump and I have 3/8 lines so mabe the other cars you mention if they were running factory steel lines then this maybe enough to reduce the flow to a level that the factory fpr can regulate with out running out of flow .

As you may have read i am overseas with no dyno and no way of buying a fpr locally so i want to be 100% sure the exact product i need to order before i order it as i dont want to stuff around with trying to set the pressure like my ra 23 as that was a way around having the wrong hardware due to misinformation

well i will post up my findings tonight as to the std fpr's output for pressure and vac then we will know for sure

cheers thrashlux

[mic*]

My 2c - ppl confuse the term. They are both rising rate pressure regulators, one is linear, one is not. Linear RRFPR are common to any boosted EFI engine iv worked on.

Great post Mos.

Thrashlux if you get the expected fuel pressures under load (~40psi + boost psig) id be leaning towards LeeRoy's theory. Do you have any accessible way to measure AFR?

[mic*]

...........expletive expletive wireless expletive coverage.........

[thrashlux]

What I aim to achive is to run as near as posible to the factory fuel pressures through out all situations
what i am guessing is that at the moment i have a higher than standard pressure throughout the range due to the fact it is obviosly running too fat under boost
This is due to the limited flow capabilities of the standard fuel pressure reg not being able control fuel pressure because of the much greater flow of the new pump and lines

So Mic what you are saying is that a rising rate regulator can have a linear or exponential output pressure curve relative to map

I thought though I may be wrong that

a rising "rate" regulator was one with an exponential curve such that the rate of pressure increase rises as the pressure increases above zero psi map

a linear pressure reg is one that for every given psi of pressure increase in the map there is a corisponding pressure increase of fuel pressure by the same amount (psi)
both these increase fuel pressure on boost just by varying amounts

Can some body else also put there 2 c in would be interested what most people beleive

thanks to all I want to get to the bottom of this some how

I know what i am doing but i would like to get the terminology correct so i dont look like a dil

thanks thrashlux

[mic*]

Sorry, to clarify; I wouldn call a linear FPR rising rate but ive known of them to be called that cause they both have pressure rates that can rise. Manufacturer's web pages that ive viewed dont mince their words.

I dont understand how you say the regulator cant handle the flow? You suspect it is going wide open and backing up more pressure than stock 40psi + psig? Possibly because your delivery lines are larger diameter than stock?

This should be apparent at idle i would have thought.

You'll soon find out whats goin on when you map it. Ill shut up till then.