Stuttering at Spa?

[The Gorilla]

Hi,

The Standard E46 fuel Pump is fine for what were
talking about.

It pumps 5.5 bar at 350mm so no problems.

If changing the pump though, then a Bosch 044 would
be my choice.

Bosch 044 Pump 120.00
Adjustable Fuel Reg 100.00
Sytec Filtre Pre Pump 60.00
Rubber Hose & Fittings 25.00

About as good as any Road / Track car will ever need
and a long way shy of the CA fix.

But as I said the hose alone is a simple easy fix for
a Car that does some Track days.

Regards,

The Gorilla.

[billy-m3cutters]

Very interstingn thread guys and very helpful indeed especially for those who do regular track days.

I would suggest this to be a sticky in a trackday section.


Well done cantfind1

[DuncanR]

Sorry not convinced

Gonna try it with some straws and Stella tonight!

Be careful not to injure Stella Shim ...

[DuncanR]

dont start that one, i did that one on the kids last week and still trying to convince them they are the same.......driving me mad :bigcry:

What you need to find mate is a 6 foot tall fookin wood pigeon !!!:hahaha:

[Bealo]

Good thread and good read :thumbs:

[cantfind1]

Hi,

The Standard E46 fuel Pump is fine for what were
talking about.

It pumps 5.5 bar at 350mm so no problems.

If changing the pump though, then a Bosch 044 would
be my choice.

Bosch 044 Pump 120.00
Adjustable Fuel Reg 100.00
Sytec Filtre Pre Pump 60.00
Rubber Hose & Fittings 25.00

About as good as any Road / Track car will ever need
and a long way shy of the CA fix.

But as I said the hose alone is a simple easy fix for
a Car that does some Track days.

Regards,

The Gorilla.

As I said if you want to be tight then yes you can do it this way, however the oem pump is definitely not up to the job, especially the old ones most of us have in our cars. They may pump that pressure when new, but they have been proven to be losing up to 10 psi at high rpm as they age.

Hey you are only risking engine damage that's all! So yeah go cheap.

I am not saying buy the CA kit, to be fair it's expensive however it is the best solution, but yes you can do this yourself with a bit of effort.

[The Gorilla]

Hi,

Cantfind1- the oem pump is up to the job.

The OEM fuel pump is pumping at over the 5 bar fuel pressure
required, its the fuel regulator that
determines the 5 bar fuel pressure delivery.

So a 10 psi drop in a OEM pump already pumping
at 6 bar +, which the OEM pump is, would not
make any difference.

''Tight'' and ''cheap'' do not enter into it.

Regards,

The Gorilla.

[cantfind1]

The 10 psi drop is not measured at the pump but after the Fuel pressure regulator.

M3 pumps loosing pressure/flow over time is well documented now.

I have found this out the hard way.

If you are tracking your car at regular intervals or revving the engine hard constantly the fuel pump needs replacing as a matter of course.

Then adding some sort of fuel pick up or second pump is a must for sweeping right handers.

[The Gorilla]

Hi,

Quote-

''The 10 psi drop is not measured at the pump but after the Fuel pressure regulator.''

Please explain, how do you know its the pump thats
faulty if its measured after the fuel pressure regulator ?


Regards,

The Gorilla,

[cantfind1]

Hi,

Quote-

''The 10 psi drop is not measured at the pump but after the Fuel pressure regulator.''

Please explain, how do you know its the pump thats
faulty if its measured after the fuel pressure regulator ?


Regards,

The Gorilla,

Because it produces the correct 5 bar at normal rpm's.

It's not until I started pushing the car constantly ie on track that the oem fuel pump started showing its weakness.

Plus my regulator was new.

Any more questions?

[shane@mbtech]

Because it produces the correct 5 bar at normal rpm's.

It's not until I started pushing the car constantly ie on track that the oem fuel pump started showing its weakness.

Plus my regulator was new.

Any more questions?

Why would pump pressure drop just because revs increase?

The pump should pump constant pressure should it not, whether at 1000rpm or 8000rpm?

The regulator controls the pressure. I concur that a weak pump would lose pressure whether it was measured after the reg or not.

The reg regulates pressure, but if at say 7000rpm the pressure needs to remain constant, then the regulator will be trying to keep pressure at say 5bar, but the pump would have to work harder due to the amount of fuel being used, in order to maintain a constant pressure. A weak pump would mean a slight drop in fuel pressure.

I think a weak pump is only part of the issue, a poor designed tank setup is another.

I never had any issues in straightline driving, just out of sharp corners on 1/4 tank.

This to me says poor pickup design rather than faulty pump, in my case.

[The Gorilla]

Hi,

Cantfind1- as Laswy says. the electric fuel pump
is constant, it has nothing to with engine rpm.

That is very reason there is a fuel regulatro.

You can only test a fuel pumps true pressure rating, when
its off the car, and there are no other factors like-

Faulty Fuel regulator-
Clogged fuel filtre-
Obstructed fuel lines-
Fuel line connectors seeping-
Fuel injector seals split or pershied-

So while your own experinces may have been
very costly, there are many items that
can impact fuel pressure.

Regards,

The Gorilla.

[cantfind1]

Guys I am not being funny but it has nothing to do with pressure and it is well known that M3 pumps deteriorate over time and do not produce the flow that they do when new.

These are not just my findings but many all over the world have experienced this and most tuners in the states who do turbo or supercharger conversions replace your oem pump as a matter of course as they have found that old oem pumps are not producing the flow that the new oem pumps do


The most demand for fuel is at high rpm, therefore you will only see problems at high rpm, not at low rpm driving around town.

I am not saying that this is the only problem with the setup, the fact that long sweeping high G right handers pull the fuel to the left side of the tank where the siphon is inadequate to pick it up is the main contributor.

However your siphon system will be weaker with a worn pump as you will not get as much fuel back from the engine rail, this is how the system works.


Lawsy if you read your post again you have pretty much answered your own question.:thumbs:

[shane@mbtech]

Guys I am not being funny but it has nothing to do with pressure and it is well known that M3 pumps deteriorate over time and do not produce the flow that they do when new.

These are not just my findings but many all over the world have experienced this and most tuners in the states who do turbo or supercharger conversions replace your oem pump as a matter of course as they have found that old oem pumps are not producing the flow that the new oem pumps do


The most demand for fuel is at high rpm, therefore you will only see problems at high rpm, not at low rpm driving around town.

I am not saying that this is the only problem with the setup, the fact that long sweeping high G right handers pull the fuel to the left side of the tank where the siphon is inadequate to pick it up is the main contributor.

However your siphon system will be weaker with a worn pump as you will not get as much fuel back from the engine rail, this is how the system works.


Lawsy if you read your post again you have pretty much answered your own question.:thumbs:

I know ~I answered my own question,

I was discussing. I like discussions such as these, very good and informative.

[cantfind1]

I agree!:thumbs: