Fuel Pump Needed ???

[GeorgeS2UK]

20 yards from the house, S2 cuts out, engine dies,
Cotinues to turn over but will not start, I have checked the fuse and even swapped it over, but I cannot hear the Fuel Pump engage when the ignition is on,
Engine did fire once or twice so I guess there was some remaining fuel in the lines, but no life now and i have drained the battery,

Managed to push it home (only 20yds or so)

I would check the relay but need to know its location, failing this I guess that the fuel pump will need checking and replacing.
.

[Graham]

Instead of starting a new thread, i jumped onto this one. I have just checked with ECP and they list a fuel pump for £59.57 inc. VAT with free postage. Is this rediculously cheap or have they made a mistake. They list it for the S2 and this is there model reference : ELECTRIC FUEL PUMP A80/ACOU/A100/A200/V8

[Henka]

You won't hear the pump with the ign on as it is not turning until you start cranking. Hook up a multimeter to the fuelpump connection and then check if you get a current with the pump connected when cranking. Also, check the voltage when cranking. If the voltage is OK (around 12-ish volts) but you don't get any current your pump is toast.

[S2 Ant]

I disagree Henka.... When you turn on the ignition, you will hear a quiet hum from the pump prepping the car before you crank it.

Graham, sounds like a bargain, flow rates would probably answer the question if its possible to find these out.

[GeorgeS2UK]

Info found on AudiFans

Researching this topic, I have found this info on

Audifans.com


Testing the Fuel Pump

If your car does not start, or your car lacks power, it may be due to a bad fuel pump. This page describes how to test the fuel pump.


Disclaimer

Work at your own risk. Neither the author of this page nor the owner of the web site accept responsibility for any damage that may occur to you or your car based on the information given here. These procedures involve raw gasoline, which is extremely flammable.


Activating the Fuel Pump
When you turn the key to start the car, that activates the fuel pump as follows.

1. The fuel pump relay (FPR) is activated, thereby sending power to the fuel pump.

2. The fuel pump, located in (or near) the fuel tank, is activated by power from the FPR.

3. The fuel pump pumps fuel from the fuel tank to the fuel rail.

4. The fuel rail feeds the fuel injectors. Some cars may have a fuel distributor, with indiviual lines to the injectors.

5. The ECU tells each injector when to open and close, controlling the spray of fuel into the intake manifold and thereby controlling fuel into the cylinder.


Testing the Fuel Pump
There are three ways to test the fuel pump:

1. Listen for the pump

2. Test the pump for flow

3. Test for power to the pump



Listen for the Pump
The first and easiest test is to listen for the fuel pump. Turn the ignition key to On, without engaging the starter. You should hear a low hum or whine coming from (near) the fuel tank. That is your fuel pump. It is building pressure in the fuel line.

If you don't hear it, test the fuel pump for flow.


Test the Pump for Flow
The fuel pump pumps fuel to the fuel rail on the engine. The fuel rail is a metal line that feeds fuel to the injectors. The metal fuel line from the fuel tank becomes a rubber line in the engine compartment. The rubber line is connected to the fuel rail with a metal ferrule and hex connector.

1. Use a wrench to crack open the fuel line connection at the fuel rail.

Be careful, as the fuel is under pressure and will spray. Cover the joint with an absorbent rag to catch the spray.

2. Place the rubber line in a glass jar (gasoline may melt plastic), then crank the engine for 3 to 5 seconds. You should get a healthy amount of fuel (1/2 pint or so) pumped into the jar. If so, your fuel pump is probably OK; you may want to test it further to see if the pump delivers the volume it should.

If no fuel is pumped into the jar, you have a fuel pump problem. Test for power to the pump.


Test for Power to the Pump
These tests require a DMM (digital multimeter or voltmeter), but a 12V test light will suffice.

There is a fuel pump relay (FPR) that energizes the fuel pump when the ignition is On. First check that the FPR is getting power.


Test for power at the FPR
The location of the FPR varies, but is usually on the fuse panel. Find it and remove it.
Turn the ignition key to On.
Connect a voltmeter to pins 48(+) and 50(-). It should read 12V. If not, there is a problem with the wiring between battery and the fuse panel.
Connect a voltmeter to pins 46(+) and 50(-). It should read 12V. If not, there is a problem feeding power to the fuel pump.
If you get 12V from both sets of pins, test for power at the pump.

Test for power at the fuel pump
The fuel pump is typically located inside the fuel tank, under a circular plate about 4" around. You don't need to remove the pump for this test; just check the wires at the connector to the pump.
With the ignition On, connect the voltmeter to the leads at the fuel pump.
If the pump is getting 12V but does not run, the pump is bad and should be replaced.
If you don't see 12V at the pump, the FPR is broken, or there may be a short (broken wire) between the FPR and the pump.

Summary
If your fuel pump checks out OK, then your fuel delivery problem may be at the injectors. See FuelInjectorTest.


Hope this help other in the future

George

PS

Still need to find out the location of the Fuel pump relay on a 3B

[martinjs]

It should be in position 10 in the fuse box.

Pic is from s2central

[nickhey]

Not directly useful, but I thought the hum heard when ignition turned on is from the turbo water pump???

Nick