Technical Fuel Pump Doesn't Work

[luqluq]

Hi guys,
Need a help here for my Mk2. My Fuel pump is not working. Checked voltage thru cable, reading is none when switched on. But when switched off, it showed a blinking 12V for a split second and back to 0V.
Searched thru the forums and found some suggestive ideas:
1. Check for cut off switch.
My question: Where is the exact location?
2. Check for fuel pump relay.
My question: Where is the exact location?
Your help(s) is(are) greatly appreciated.
Thank you.
Luqluq

 

[judderbar]

Hi guys,
Need a help here for my Mk2. My Fuel pump is not working. Checked voltage thru cable, reading is none when switched on. But when switched off, it showed a blinking 12V for a split second and back to 0V.
Searched thru the forums and found some suggestive ideas:
1. Check for cut off switch.
My question: Where is the exact location?
2. Check for fuel pump relay.
My question: Where is the exact location?
Your help(s) is(are) greatly appreciated.
Thank you.
Luqluq

The fuel pump relay depends upon which engine fuse box arrangement you have. They have the same fuse box with different relays and fuses. The relay is one of the ones marked with the injector picture.

The cutoff switch/relay controls the purple fuel pump earth.

You can find the cut off switch/relay under the glove box on the far right hand side of a left hand drive car. It is behind the carpet at the very top of the carpet about 30 cms from the floor.

 

[s and b]

if you are sure the fuel pump works?
check the earth connection on top of your throttle body
find the fuel pump switch up the front door A post on the left side as you look out of the windscreen
the relay is behind the dash,cant remember where but look at the bsi relays first,you should hear it click when ignition first turned on assuming your key is being recognised at cranking

 

[luqluq]

Dear Judderbar & S n B,

Thank you very much your your kind replies. Managed to find the cut-off switch and the relay marked T10 with the injection symbol.

So this morning, quickly sourced for the parts. Did for the cut off switch first and no effect. After that, changed the relay and ... Hurrah!!! the burst of fuel came out from the fuel pump.

Thank you very much guys for your kind helps. I'm smiling from ear to ear now, the engine is purring as before

Luqluq

(S n B, FYI, the pump that I replaced has already been checked before, thanks)

 

[luqluq]

Last weekend, I put back the fuel pump back to the donor car where it originated. The pump is working but when installed back, it didn't work any more. I replaced the T10 relay and tried, it didn't start. After that, I replaced the cut off switch and even after that, direct connect, it still didn't start. Then I connect the fuel pump directly to battery, only it can start.
My questions:
1. What is the possible cause on the circuit? The donor car engine used to be running ok.

2. If the pump is connected to battery, means it's running continuously, will it be bad to the system?
Thank you.
Luqluq

 

[varesecrazy]

The fuel pump relay depends upon which engine fuse box arrangement you have. They have the same fuse box with different relays and fuses. The relay is one of the ones marked with the injector picture.

The cutoff switch/relay controls the purple fuel pump earth.

You can find the cut off switch/relay under the glove box on the far right hand side of a left hand drive car. It is behind the carpet at the very top of the carpet about 30 cms from the floor.

luqluq

This appear to offer the answer.

Different options on the route of power supply.

 

[jesusminmy]

How did you connect the fuel pump
direct to the battery

 

[judderbar]

Last weekend, I put back the fuel pump back to the donor car where it originated. The pump is working but when installed back, it didn't work any more. I replaced the T10 relay and tried, it didn't start. After that, I replaced the cut off switch and even after that, direct connect, it still didn't start. Then I connect the fuel pump directly to battery, only it can start.
My questions:
1. What is the possible cause on the circuit? The donor car engine used to be running ok.

2. If the pump is connected to battery, means it's running continuously, will it be bad to the system?
Thank you.
Luqluq

Are you confidant you are using the donor cars key to start the car? does the key code light go out?


The pump can be run continuously if it is submerged in petrol otherwise it will get hot and eventually burn out. In normal operation, once the car starts the pump runs continuously until the engine stops running.

My car has a T10 relay for the pump.


Without the key in the ignition, and T10 removed, the pump should always run when the large contacts of the T10 position, which are the two nearest the fuses, are bridged or connected together by a short piece of wire. The purple yellow wire at the pumps connector under the seat is a single piece of wire going to the fuse box and then connected without fuses to the large T10 connector most far from the fuses. The large T10 connector most near to the fuses is fused by Fuse 21.

 

[luqluq]

How did you connect the fuel pump
direct to the battery

I just drag cable from the battery to the fuel pump.
There are 4 cables at the pump. 2 small cables to send petrol level info to the tachometer. The two bigger cables are for the negative and positive which will run the motor in the pump.

 

[luqluq]

Are you confidant you are using the donor cars key to start the car? does the key code light go out?


The pump can be run continuously if it is submerged in petrol otherwise it will get hot and eventually burn out. In normal operation, once the car starts the pump runs continuously until the engine stops running.

My car has a T10 relay for the pump.


Without the key in the ignition, and T10 removed, the pump should always run when the large contacts of the T10 position, which are the two nearest the fuses, are bridged or connected together by a short piece of wire. The purple yellow wire at the pumps connector under the seat is a single piece of wire going to the fuse box and then connected without fuses to the large T10 connector most far from the fuses. The large T10 connector most near to the fuses is fused by Fuse 21.

Both car are identical MK2 except the colour and key code. And yes, I was using the right key as they are not interchangeable and the key code did light out.

I'll try to sort the things after this. Thanks a lot, Judderbar for the good explanation.

 

[Ziggy122]

Well if pump works in donor and doesnt works off a battery- it tells me an issue with the vehicles wiring

Id be sticking a test light into the connectors (something semi juicy like a h7 bulb) and find out which side is missing
Positive or negative

Ziggy