Mkii Ute Fuel Pumps

[F6_Tornado]

WOW, what a Post, or series of posts.

Some great info here.

I have been worried about my fuel pump for a while, and after reading the above, I will do a pressure check this afternoon and see how it goes.

I am sure my car has fuel supply probs,

If I use my 293rwkw tune, when pushed hard for extended runs of constant flat out running, the car will alot of the times loose power, back off for a few seconds and its fine again, it will do it in hot or cold weather etc etc, I am only running 11psi boost so I dont think its overboost.

When I run the 277rwkw map it shows no signs of doing it, ever, lower boost and fuel map, so less fuel required, no Probs.

A fuel pressure check should tell me.

<{POST_SNAPBACK}>

Do a test stationary at Idle and get the relief valve setting for a start.

A second good way to test this then would be to drive it with the 277rwkw map (long hose into the cab) and select say 3rd or 4th gear as low rpm, say 1200rpm and then give her WOT and watch the fuel gauge as it moves through the rev range watching it rise with Boost and noting if it suddenly drops 50~100kpa…then put in the High hp 293rwkw map and do it again and take note of the KPA at which it suddenly drops.

This should match your test done at idle and confirm the relief is going off.

And most of all probably explain the surging etc that you experienced.

[F6_Tornado]

Another thing to keep in mind is a relief valve may let go at say for an example at 450kpa and instantly drop to 375kpa and it may well stay at that point until the pressure drops even lower before the valve resets and allows the pressure to rise again towards the 450kpa.

So again it’s important to note the pressure at which it resets itself which will vary slightly but be anywhere between a 50~100 kpa lower than the relief setting.

If you can picture in your mind the map demanding 12 psi Boost and in return having 500kpa fuel pressure >>>>then it suddenly dropping to 400kpa……. It has no choice but to lean out to the max!!!!!!!!!!

There are other factor to consider such as the max setting of the rising rate reg to take into account and as such I don’t think its capable of more than @ 525Kpa~ 550Kpa but that’s another day…

[turbotom]

Great post guys.....

Might go some way to explaining why my ute still suffers a momentary "ping" under WOT accelleration just on the 1~2 change when fuel level in tank is less than 1/2 full.

It did this when I installed the APS Ph II kit, and now, even with an inline Bosch pump (APS PH III type), it still occurs

I wanted to install the wallbro intank pump, but the guys doing the mods (fitting APS IC) couldn't get it to fit, and so I went with the inline pump.

hmmmm, Not happy that it has NOT rectified the problem.

So let me see if I understand this post.

I should monitor the fuel rail pressure to determine if there is a drop off under WOT.

Then it's a matter of determining if the pressure drop is due to the relief valve in the intank pump opening prematurely. ( Tested by clamping the return fuel line, which effectively increases the pressure on the relief valve till it pops open. )

OR

the quantity of fuel in the (intank) swirlpot runs dry........ causing fuel starvation.

(How would this be verified?)

So what pressure should be available at the fuel rail for 15 psi of boost?

What about for a higher power app at 18 psi?

If its a matter of modifying the relief valve on the intank pump, that's sweet.

But I guess the other option would be to fit a larger swirl pot, external to the tank.

have I got this info correct?

cheers

tom

[F6_Tornado]

Great post guys.....

Might go some way to explaining why my ute still suffers a momentary "ping" under WOT accelleration just on the 1~2 change when fuel level in tank is less than 1/2 full.

It did this when I installed the APS Ph II kit, and now, even with an inline Bosch pump (APS PH III type), it still occurs 

<{POST_SNAPBACK}>

Pinging is not a product of low fuel pressure. Its more timing and/or Fuel octane related.

I wanted to install the wallbro intank pump, but the guys doing the mods (fitting APS IC) couldn't get it to fit, and so I went with the inline pump.

hmmmm,  Not happy that it has NOT rectified the problem.

<{POST_SNAPBACK}>

The Aftermarket Walbro pump is a pain to fit and is in no way a direct replacement drop in fit…Quite the opposite and requires some small engineering. But 15 mins and some clever thinking will do it.

So let me see if I understand this post.

I should monitor the fuel rail pressure to determine if there is a drop off under WOT.

<{POST_SNAPBACK}>

yep lug it from low revs through to High rpm in a gear like 4th and monitor the fuel pressure.

Then it's a matter of determining if the pressure drop is due to the relief valve in the intank pump opening prematurely.  ( Tested by clamping the return fuel line, which effectively increases the pressure on the relief valve till it pops open. )

<{POST_SNAPBACK}>

Yes you can also test the relief valve setting by restricting the return line back to the tank ..”slowly” NOT CLAMP IT OFF or you may well damage your pump so be gentle.

the quantity of fuel in the (intank) swirlpot runs dry........ causing fuel starvation.

(How would this be verified?)

<{POST_SNAPBACK}>

More a case of when the fuel tank is low and the relief valve is going off the fuel level in the swirl pot will be reduced and as such may well cause starvation and cavitation as it draws air & fuel in making the relief valve even more erratic.

So what pressure should be available at the fuel rail for 15 psi of boost?

What about for a higher power app at 18 psi?

<{POST_SNAPBACK}>

Id say from the tests I’ve done around 525kpa….. more for the reason that I think that is the max the STD Ford Regulator will produce so minimal to no difference once you pass the 15psi mark.. But more tests will confirm or dispute that.

If its a matter of modifying the relief valve on the intank pump, that's sweet.

But I guess the other option would be to fit a larger swirl pot, external to the tank.

<{POST_SNAPBACK}>

Modifying the existing pump relief valve is all that is required “if” this is the problem with your particular vehicle and you are looking at @ 300 rwkws or slightly more.

I have not tested mine above that as that is my limit at present but in theory it’s capable of much more.

Forget the swirl pot because I personally don’t believe for a min it’s a big problem. Quite the opposite in fact I think it’s been getting blamed when all along it’s has been the relief valve in the pump.

Anyways it costs nothing to test it if you have the know-how and after testing it “correctly” use those results to justify what path you wish to take.

If it’s modify the relief? Then you may well save yourself the $330.00 on the aftermarket walbro pump and the headaches associated with fitting one not to mention the cost. The performance shops wont be happy as they lose on the sale of the pump and the fitment.

[turbotom]

Thanks for the extensive reply, F6 Tornado....

Just a further query, regarding your comment that "pinging" occurs due to timing or octane. I won't dispute that at all. You are correct.

But why do I get the "ping" occurring only when the fuel level drops in the tank?

If it was octane or excessive advanced timing, it would occur irrespective of fuel level, in fact it would probably occur more readily with a heavier (full fuel) load...

I'll get the relief valve checked when I take the car in for check of the tune.

Hopefully it is as simple as that.

thanks

tom

[bjc]

F6 Tornado,

After reading the novel above are you going to tell us how to mod the relief valve? or is this a secret squirrel thing also.

Brett

[F6_Tornado]

F6 Tornado,

After reading the novel above are you going to tell us how to mod the relief valve? or is this a secret squirrel thing also.

Brett

<{POST_SNAPBACK}>

I wondered where this tread went hahahhah

No secret squirrel here mate…

Buy a 5mm X 5mm grub screw from your local automotive Parts supplier and drill a hole through it ..say 3~4 mm.

Remove the relief valve spring from the pump and cut it in ½ and then use the grub screw to set the relief valve pressure.. (Now adjustable)

The Grub screw costs about $0.40 so it’s a whisker cheaper than a new pump.

I’d suggest you only get a qualified mechanic to do this and make sure the relief is set and working correctly!!!!!!! Not that is hard co’s its not just when playing with Petrol, Electric Pumps and Pressure you have a recipe for a major drama if you go about it wrong.

I set mine to @ 850KPA which is heaps and my fuel pressure under full boost has only ever spiked to @ 530kpa so now I never have the surging or leaning out under WOT.

[bjc]

Thanks buddy, this will save me money and I can show my mechanic this so he knows how to do this.

He was trying to talk me into buying a new pump but I kept saying there is a cheaper way of fixing the problem.

Thanks again,

Brett

[adams355]

On 10/22/2005 at 7:52 AM, F6_Tornado said:

I wondered where this tread went hahahhah

No secret squirrel here mate…

Buy a 5mm X 5mm grub screw from your local automotive Parts supplier and drill a hole through it ..say 3~4 mm.

Remove the relief valve spring from the pump and cut it in ½ and then use the grub screw to set the relief valve pressure.. (Now adjustable)

The Grub screw costs about $0.40 so it’s a whisker cheaper than a new pump.

I’d suggest you only get a qualified mechanic to do this and make sure the relief is set and working correctly!!!!!!! Not that is hard co’s its not just when playing with Petrol, Electric Pumps and Pressure you have a recipe for a major drama if you go about it wrong.

I set mine to @ 850KPA which is heaps and my fuel pressure under full boost has only ever spiked to @ 530kpa so now I never have the surging or leaning out under WOT.

 

Is this method still viable, sorry for the thread mine...

[arronm]

Its 2018. This is no longer required with the aftermarket parts available. In 2005  a 300-350rwkw car was KILLA