Just did the test again but measuring the flow at the fuel inlet , without the engine running, bridging the pump relay. The 044 gave around 1.3l in 15 seconds, which I presume is about right from Andy's post above.
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Could be failing under load?
Are you sure the pump you have in genuine? Have you seen this thread?
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1991 Audi S2 3B - 2.5 Stroker engine
1997 A6 2.5TDi quattro avant - C4
1976 RD250E / 350LC cafe racerComment
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Measuring at inlet is useless.
You have to measure through the return but obviously with the engine not running while you do it.
If your stock pump is giving you 60l/h on return it's screwed.
If your 044 pump is giving you 750 180l/h at 4 bar it's screwed as well, as a brand new pump gives around 300l/h in this circumstance.
Perform the tests correctly - doing them without any FPR connected is a waste of time.
The only thing he is doing incorrectly is that he is measuring it with engine running.Comment
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Yes and you did that right, just don't do it with the engine one.
Run the fuel pump manually and re-test...
But from all those numbers your posted both your pumps are bad.Comment
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I have seen that thread thanks mate. Mine seems genuine as its helicoiled and looks externally like the the real one. However, I must admit that where the part number is engraved it looks very 'shallow' if that makes sense.
Think I'm going to have to investigate this one further.Comment
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Just found this info from Bosch
That suggests that the 044 actually flows 200lph @ 5 bar. That just over 800ml in 15 seconds.Comment
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That manual is wrong, that's all.
It's not how you measure pumps.
Doesn't matter what it pumps with no resistance, if the pump is messed up it can still deliver more or less adequate performance with no load, and drop down to 50ml when load is applied.
The only valid test is measuring through the FPR. Best if some pressure is applied to the FPR as well, preferrably the same pressure as is present on the peak hp point.
Here is some flow data for the 044:
It is underrated from factory.Comment
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Interesting read.That manual is wrong, that's all.
It's not how you measure pumps.
Doesn't matter what it pumps with no resistance, if the pump is messed up it can still deliver more or less adequate performance with no load, and drop down to 50ml when load is applied.
The only valid test is measuring through the FPR. Best if some pressure is applied to the FPR as well, preferrably the same pressure as is present on the peak hp point.
Here is some flow data for the 044:
It is underrated from factory.Comment
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Fuel Pump Curves - Theory and Practise
Yeh, pity the idiots at Bentley who write up those procedures for the Audi shop techies to test fuel pumps already installed in existing vehicles. What fools. They should have consulted you first
Pump curves are always a compromise combination of flow and pressure. Pumps can either produce lots of pressure but very little flow or lots of flow but very little pressure or a combination of both. I know, based on work done by Sean D. (quattro20V) using pressure source attached to his fuel pressure regulator when we worked on relaying the C4 UrS fuel pump directly to the battery (How to "Turbo Charge" your Fuel Pump: DIY instructions for adding a battery-to-fuel pump relay ) , that the OE 091G fuel pump will produce around 86 psig. However, I also know from my RS2'd UrS5 that the flow capacity of the 091G is starting to be (or is) maxxed out at that pressure. This gets people interested in fuel pumps with more flow capacity at these pressures, e.g. 6 Bar, like the Bosch Motorsport 044 (or 040 or 005).
(86 psig is critical to an RS2'd AAN because 4 bar = 58 psig and 28 psig boost = the pump needs to supply at least 86 psig and all the flow required by the injectors as the ECU keeps them open on a duty cycle that is likely approaching 90% at WOT).
Just for reference, here is an exaggerated fuel pump curve (the black line):
Here is a less exaggerated Bosch 044 pump curve:
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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[QUOTE=UrS4boy;844811]Yeh, pity the idiots at Bentley who write up those procedures for the Audi shop techies to test fuel pumps already installed in existing vehicles. What fools. They should have consulted you first
Pump curves are always a compromise combination of flow and pressure. Pumps can either produce lots of pressure but very little flow or lots of flow but very little pressure or a combination of both. I know, based on work done by Sean D. (quattro20V) using pressure source attached to his fuel pressure regulator when we worked on relaying the C4 UrS fuel pump directly to the battery (How to "Turbo Charge" your Fuel Pump: DIY instructions for adding a battery-to-fuel pump relay ) , that the OE 091G fuel pump will produce around 86 psig. However, I also know from my RS2'd UrS5 that the flow capacity of the 091G is starting to be (or is) maxxed out at that pressure. This gets people interested in fuel pumps with more flow capacity at these pressures, e.g. 6 Bar, like the Bosch Motorsport 044 (or 040 or 005).
(86 psig is critical to an RS2'd AAN because 4 bar = 58 psig and 28 psig boost = the pump needs to supply at least 86 psig and all the flow required by the injectors as the ECU keeps them open on a duty cycle that is likely approaching 90% at WOT).
Just for reference, here is an exaggerated fuel pump curve (the black line):
Here is a less exaggerated Bosch 044 pump curve:
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I see where you're going with this, but I'm trying to keep it simple. The pump produces flow, not pressure. Even the most worn out pumps might flow perfectly fine If tested at the fuel rail inlet (with no resistance to flow). It also appears that the 044 is able to flow very well even as the pressure increases past 5-6 bar.
I need to identify whether my pump is failing to deliver the required fuel flow when under the pressure applied by the fuel pressure regulator.Comment
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Pumps can produce LOTS OF PRESSURE at shut off, i.e. a valve being closed or a fuel line clogged/pinched. OR they can produce lots of flow without restrictions. Or a combination of both. Just don't try to tell me that pumps don't produce pressure.
This is correct. If you read my "Turbo charge your fuel pump" link, you can do such a test with the engine off by applying an artificially-sourced (air compressor with a variable pressure adjustment) pressure on the "vacuum/boost" nipple on the top of the fuel pressure regulator. In this case, testing the flow at the discharge of fuel rail would be appropriate. But not otherwise, in my opinion. Apples to apples, oranges to oranges.
RS2'd 93 UrS4 5 spd sedan
94 UrS4 V8 6 spd manual avantComment
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Perhaps they should have then the fuel pump test procedure would be correct.
What separates me and you is that apart from just reading factory specs my company tunes and designs fueling systems far exceeding stock specifications.
If you had any real-world experience with this, you would not be arguing with me about this, as it is clear to anyone who has experience with designing fuel systems that the flow must be tested under the correct operating pressure that the system is operating at, not without resistance.
If applied into electronics terms, it's like measuring whether a power supply has a voltage drop without any load at all on it, when in reality it always runs under load and the brownout should be tested at that load.
That's precisely what you need to do. Just measure the return at 4 bar. Your 044 should deliver at least 250 lph, and the stock pump should be around 130 lph.Comment
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