changed fuel pump. tune ramifications?

GR124 · Postby **GR124** » Mon Feb 03, 2020 9:00 am

Hey guys, with one week before the first race of the year my fuel pump sprung a leak (don't ask how, :oops:

)
Engine details - N/A BP4W, standard other than Elite 750 ECU, 640 injectors, on E85. STANDARD OEM Fuel Pressure Reg Fuel pump is external
The pump that leaked was a Bosch 044 (580 254 044). was never happy with the 1KG weight of it anyway, just bought a Deatschwerks DW250iL, it's in the mail.
Both these pumps on paper look to flow the same and pressure the same, or very close.

I can't possibly get another tune before Wakefield next weekend.

Will all be OK???

StuwieP · Postby **StuwieP** » Tue Feb 04, 2020 10:23 pm

If pressure at the injector is the same, and the pump can sustain equal pressure to that the car was tuned on, what difference could it make?

Even if you put a big pump in, you'd just be cycling more fuel through the pressure regulator, right?

Sorry that's not exactly conclusive but yeah... can't see how it would?

GR124 · Postby **GR124** » Wed Feb 05, 2020 10:00 am

StuwieP wrote:If pressure at the injector is the same, and the pump can sustain equal pressure to that the car was tuned on, what difference could it make?

Even if you put a big pump in, you'd just be cycling more fuel through the pressure regulator, right?

Sorry that's not exactly conclusive but yeah... can't see how it would?

I spoke to several people including my tuner, you seem to be correct, so I'll throw the new pump in and see how it goes.
Thanks for your response.

Magpie · Postby **Magpie** » Wed Feb 05, 2020 10:17 am

Pump has no impact on tune unless it cannot maintain the required flow and pressure required.

If you are replacing the pump be aware of current draw increase on the OEM wiring and fuses.

I have a Walbro 460 pump in the surge tanks and it draws 14 amps at 13.7 volts and a Walbro 255 as a lift pump and it draws 3.2 amps at 13.7 volts.

The surge tank maintains about 42psi to 725ID injectors. Peak injector duty cycle is about 75% at full noise. Car runs on E85.

These are real numbers from my last session at QR (01/02/20).

Your injectors maybe running at a very high duty cycle, you may want to log the injector duty cycle.

GR124 · Postby **GR124** » Wed Feb 05, 2020 11:06 am

Magpie wrote:Pump has no impact on tune unless it cannot maintain the required flow and pressure required.

If you are replacing the pump be aware of current draw increase on the OEM wiring and fuses.

I have a Walbro 460 pump in the surge tanks and it draws 14 amps at 13.7 volts and a Walbro 255 as a lift pump and it draws 3.2 amps at 13.7 volts.

The surge tank maintains about 42psi to 725ID injectors. Peak injector duty cycle is about 75% at full noise. Car runs on E85.

These are real numbers from my last session at QR (01/02/20).

Your injectors maybe running at a very high duty cycle, you may want to log the injector duty cycle.

Hi Magpie,
I'm a little simple when it comes to this stuff. Please help.
I have ordered a DW250iL pump. as it was pretty equal to the Bosch 044 I had in it.
Just thinking about future proofing myself,,,,,,,if I was go turbo with 250-280WHP (worst case) on E85 should I look at the DW350iL.

GR124 · Postby **GR124** » Wed Feb 05, 2020 11:42 am

OK after going through a couple of on line "fuel pump calculators" it looks like a Deatschwerks DL250il will be fine for 250HP on E85. Assuming 1000cc injectors. Possibly on the limit but ok.
can anyone confirm this? for this simple man

Magpie · Postby **Magpie** » Wed Feb 05, 2020 11:55 am

I would talk to your tuner to get his advice, on paper it looks fine.

Again, look at the wiring as you will be drawing around 13 amps and you want to make sure you have no voltage drop at the pump. The specs assume that you have 13.5 volts. The OEM wiring maybe good for 15amp so you will be cutting it fine.

If you are concerned turn on the engine protection in the ECU. I assume you have an AFR fitted? If you set the engine protection on the AFR and it does not trigger then your choices are correct...

GR124 · Postby **GR124** » Wed Feb 05, 2020 12:07 pm

Magpie wrote:I would talk to your tuner to get his advice, on paper it looks fine.

Again, look at the wiring as you will be drawing around 13 amps and you want to make sure you have no voltage drop at the pump. The specs assume that you have 13.5 volts. The OEM wiring maybe good for 15amp so you will be cutting it fine.

If you are concerned turn on the engine protection in the ECU. I assume you have an AFR fitted? If you set the engine protection on the AFR and it does not trigger then your choices are correct...

I have no OEM wiring, so I'm not concerned there. As per the engine protection, I don't believe the Haltech Elite 750 has protection.
I'll talk to my tuner, Thanks

Magpie · Postby **Magpie** » Wed Feb 05, 2020 2:41 pm

Ignore my wire comments then

My car has no OEM wiring in it either

GR124 · Postby **GR124** » Wed Feb 05, 2020 4:32 pm

Magpie wrote:Ignore my wire comments then

My car has no OEM wiring in it either

I'm going to side track the thread here, Is that a Craig Davies water pump controller? I'm keen to go the electric water pump route.
Can I asked which model, you run? Are you NA or turbo?

Magpie · Postby **Magpie** » Thu Feb 06, 2020 7:13 am

No that is a Crag Davies low water level alarm.

Car is Naturally aspirated.

GR124 · Postby **GR124** » Thu Feb 06, 2020 8:18 am

Magpie wrote:No that is a Crag Davies low water level alarm.

Car is Naturally aspirated.

Cool, Cheers Magpie

mx589 · Postby **mx589** » Sat Feb 15, 2020 9:18 pm

Not hard to check fuel pressure and quick run over of af ratios with wideband to cover yourself like others have said. Factory fuel regulators can also cause grief when you try run a 2 large fuel pump with them