Mkii Ute Fuel Pumps

[Trough Lolly]

ive asked this in a few different threads but never got the answers I was after.. basically will the intank pump be enough to flow to 290 at the wheels without surging??

if not what can I use? instead of replacing the dreaded in-tank unit which is a c&*t to install, can I just add a small inline pump or sumthing to help the intank unit out a bit??

any suggestions very helpful!! thanks.

ps- the car is going to have: valve springs, custom capa edit, hi-flow cat, 968's, CAI mods.

[philldub]

When you talk to Nizpro tomorrow ask them.Should be fine I'm told

[F6 UTE]

Mine runs 280 rwkw, no surging.

Which clutch are you going to get??

[Trough Lolly]

im only running a stock clutch for now.. the car only has 12,000 kms on it so its still new.

when its rooted down the track ill probly get a extreme clutch or sumthing. not fussed about it yet that's way down the track.

[F6_Tornado]

ive asked this in a few different threads but never got the answers I was after..  basically will the intank pump be enough to flow to 290 at the wheels without surging??

if not what can I use? instead of replacing the dreaded in-tank unit which is a c&*t to install, can I just add a small inline pump or sumthing to help the intank unit out a bit??

any suggestions very helpful!! thanks.

ps- the car is going to have: valve springs, custom capa edit, hi-flow cat, 968's, CAI mods.

<{POST_SNAPBACK}>

Ok Ill be brave and tell you if your pump will supply enough fuel @ 290rwkw’s.

Let’s look at mine as an example:

F6 Tornado STD fuel pump not sufficient @ 270FWKw’s

Changed under warranty and the second fuel pump was “just” OK with STD 270FWKws but struggled with edit.

Changed the in-tank pump with a high flow Walbro and now its fine @ 300rwkw’s.

Why?????

Well you have to consider how it works and why changing the pump and/or fitting a inline pump has solved many members problems.

To do this we need to know what the problem is with the factory pump and its not what most people think and that is it has insufficient flow and/or swirl pot design

Consider some fact:

GT and XR8 run the same pump as the XR6T and the F6 so what is the difference as we never have a drama with the V8’s and to some extent the STD XR6T but borderline on the F6 and modded XR6T’s?

GT, XR8, XR6T & F6 run 350kpa fuel pressure at closed loop

GT, XR8, XR6T & F6 run 400kpa fuel pressure at open loop

So for this case there is no difference and the flow is cool on all counts so why do we have problems?

The XR8 & GT don’t have boost and as such the only variation in fuel pressure is controlled by the inlet manifold pressure which can only be a vacuum or atmospheric pressure.

So in this instance at idle (closed loop) we should have a vacuum and 350kpa fuel pressure and as we open the throttle (open loop) we change from the vacuum to atmospheric pressure and the fuel regulator then sets the fuel pressure to 400kpa.

Simple enough and never a problem until we stretch this to the next stage which is add some boost from a turbo engine to the fuel regulator and what happens? The fuel pressure must rise again and in the case of a STD XR6T to around 450kpa with 6psi Boost follow?

Fuel regulator, approximates, Examples:

Vacuum = 350kpa

Atmosphere = 400kpa

XR6T= 6 Psi boost = 450kpa.

See where we are going?

Next step is F6

F6 = 9psi boost = 500kpa

Edited XR6T = 10~12 Psi = 510kpa

Edited F6 = 525kpa

Ok now we can see we are demanding a higher fuel pressure as we increase boost and as such we can force more fuel through the injector.

So how does the factory pump handle this increase in pressure?

In Short not very well at all!!!!

If we go back to my first paragraph you will notice my first factor pump was useless at STD power because the fuel pump relief valve was leaking off @ 450kpa and as such the pressure would drop to 350kpa which is insufficient to maintain the required HP leaning out.

The second pump however would hold pressure to @ 475kpa and as such fine for STD hp but insufficient for edit as the demand exceeded 500kpa and the relief would leak off and the fuel pressure would drop to 450kpa which is insufficient for that hp.

The aftermarket High flow pump would hold 800kpa and as such the target hp in this case was 400fwkw’s (300rwkw’s) and not a problem.

The thing is the pump may flow 3ltr a min factory but when 1.5 ltr a min is going out the relief valve the flow is then rendered insufficient as such and results in lack of fuel and surging and lean a/f.

The relief valve is part of the pump itself and as such is not adjustable and varies from pump to pump taking into consideration the pressure is taken at the fuel rail and not prior to the filter where it may well be higher.

Ok so to prove it is not a pump flow problem and a relief valve problem (which ultimately effects flow) we can bastardise the factory pump and increase the relief valve setting to 800kpa and test on the dyno and see what we get… which is no leaning out of the A/F and no pressure drop at max boost!!!!!!!!!!!!!!!!!!

So to answer your question on, “is the factory pump sufficient for 290rwks” I can only say Yes and No……

Remembering the pumps vary from vehicle to vehicle and F6 UTE hold pressure to 510 ~ 520 kpa but drops every other run and as such is borderline whereas my First factor pump wouldn’t handle 450kpa before leaning out as the relief went off.

To test this is quite simple and can be done with an 800kpa Gauge and a T piece in the fuel supply line.

Don’t even attempt this if you’re not a mechanic:

With the engine at idle and the gauge in place you should see 350kpa on the dial……Now using something as simple as a pair of pliers slowly squeeze the return line watching the fuel pressure gauge rise … now make sure you do this very very slowly the pressure will rise and at some point it will suddenly drop…. This is the point which the relief valve is letting go and the point at which your engine will lean out to the max under full noise.

Do this slowly several times @idle to get an accurate reading of the relief valve pressure.

NOTE: do not squeeze off the return line to much as this will restrict the flow to a magnitude greater than the relief valve can handle and as such the fuel pressure will then rise to above 800kpa and give you a totally false reading.

By fitting an inline pump you are using the inline pump relief valve and not the factory relief valve and as such have indirectly fixed the problem.

The factory PUMP will flow enough for 300++rwkw’s without any problem at all if the relief valve is modded to ensure no premature blow off and loss of flow by way of the relief valve.

So much more I could write but I think you get the idea!!!

BTW The clutch will fall out long before you get to 290rwkw’s and 650nm

[F6 UTE]

Very well said.

My first run on the dyno went 395rwhp (297rwkw), every successive run after that saw the relief valve 'pop' and hence run lean after a short squirt, so boost was dialed down to a point where the pump held its guts together. Seems it was 15psi + 280rwkw, running 10.0's (afr) in the top end as a safeguard incase the relief valve 'popped' again.. It will, with the mod to the pump go to 300rwkw I'm sure, and keep nice afr's..

I have the 'small' nizpro drilled injectors aswell, not the bigger ones that F6 Tornado and a few of the other guys are running, so it will be interesting to see how my series of mods compares to the other guys..

And yes, once you get off the dyno, you'll buzz your clutch. Extreme do a nice 10.5" with replacement flywheel for about $1.1k.

[Trough Lolly]

F6 tornado... thanks for that HUGE informative post but after that much info going thru such a little brain im a bit lost now!! lol..

basically summing up, the stock in-tank pump will be sufficient IF a inline pump is added to help take the stress off the relief valve of the in-tanker??

excuse my lack of brains this week I got that much going thru my head about this bloody car im at the point of exploding!

[F6 UTE]

By fitting an inline pump you are using the inline pump relief valve and not the factory relief valve and as such have indirectly fixed the problem.

The factory PUMP will flow enough for 300++rwkw’s without any problem at all if the relief valve is modded to ensure no premature blow off and loss of flow by way of the relief valve.

So much more I could write but I think you get the idea!!!

<{POST_SNAPBACK}>

[Buf-Phoon]

F6 tornado... thanks for that HUGE informative post but after that much info going thru such a little brain im a bit lost now!! lol..

basically summing up, the stock in-tank pump will be sufficient IF a inline pump is added to help take the stress off the relief valve of the in-tanker??

excuse my lack of brains this week I got that much going thru my head about this bloody car im at the point of exploding!

<{POST_SNAPBACK}>

Trough Lolly thanks for that my question exactly, though if the in tanker doesn't have enough grunt the inline pump will be starved also wouldn't it.

[Trough Lolly]

ok now im all confused!!! lol..

OK, What should I do on the cheap to get it working at those power levels?