EUC /fuel relay 1.4tdi 53 plate

C

Carl R

New Member
Hi,
I have had some issues with my A2tdi being difficult to start over warm.
I wanted to try replacing the ECU / fuel pump relay. I have bought one that has 100 on the top of it but when I look in the front left under floor relay and fuse carriers the one I think it slid be has 612 on the top. Is this the same? Can I safely re place it with a 100 relay?
My electrical knowledge is very limited.
 
Not yet, it always starts first time in the morning and can randomly start first time for a couple of days. But it can also cut out from time to time then take a lot of turns to start.
mince I’ve tried the relay I’ll be working my way through the rest of the potential issues or it will be fixed?? Fingers crossed
 
Can anyone help me locate the 6-6 replay carrier on an A2 53 plate 1.4 tdi?
I need to replace the ecu/fuel relay
 
I have decided that the relay carrier in the passenger side footwell under the floor is not where the fuel pump/ecu relay is located. From what I’ve already read or seems to be in the 6+6 relay carrier but I cannot locate that carrier? Any ideas where this is?
 
It is in the compartment under the front left floor. access it by lifting the carpet then remove the aluminium panel. It is located in front of the CCCU and ECU boxes.
Here is a picture of the area under the floor taken by @ajsellors

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ECU / fuel relay? Where have you got that description from and what makes you think that is faulty? Fuel is purely mechanical and has no relay.
 
The starting issue could be the cam or crank sensor or a leaking tandem pump. You really need to have a VCDS scan done on the car to take out a lot of the guess work. Out of curiosity if the car parks downhill does it start everytime when hot?
 
audifan said:
See my post on your other thread. You effectively have 2 threads with the same issue. High chance that you will get answers spread over the 2 and overlap or miss something. Either try to get a moderator to merge the 2 threads or delete one to prevent multiple or missed posts. Do not assume the A2 is the same as other cars, that way "red herrings" can be avoided.
Click to expand...
A little untidy but merged Graham. I’ll try to tidy it up later on but at least it’s all in one place now.

@Carl R, it looks like you’re receiving the necessary support required. You’re in good hands with Graham and Robin.

Kind regards,

Tom
 
audifan said:
The starting issue could be the cam or crank sensor or a leaking tandem pump. You really need to have a VCDS scan done on the car to take out a lot of the guess work. Out of curiosity if the car parks downhill does it start everytime when hot?
Click to expand...
The starting problem is totally random uphill downhill didn’t make any difference.
It starts every time on the key but once warm it sometimes takes a lot of cranking to start. Strangely when it takes time to start it cuts out quite quickly after that.
When it starts from cold it never cuts out.
 
2work said:
A little untidy but merged Graham. I’ll try to tidy it up later on but at least it’s all in one place now.

@Carl R, it looks like you’re receiving the necessary support required. You’re in good hands with Graham and Robin.

Kind regards,

Tom
Click to expand...
Thanks
 
One last thing I’ve noticed or rather not noticed is when I turn on the ignition I don’t hear any thing from the fuel pump? Should I hear anything coming from the back of the car?
 
Carl R said:
..... I don’t hear any thing from the fuel pump? Should I hear anything coming from the back of the car?
Click to expand...
On a TDi, the fuel pump is a big metal component bolted onto the right end of the engine block (tandem pump). There is no supplementary tank pump unless it is a *VERY* early A2 or a 1.6 FSi (petrol engine) (where there is also a secondary pump in the tank). I should stress that what little information I have about second fuel pumps in the tank come from anecdotes reading a lot of comments on A2oc when these discussions arise from similar mechanic diagnostic questions - the general consensus is that most A2s do not have a second fuel pump in the tank but there are some exceptions, namely : very early cars, and 1.6FSi (the low pressure pump needed to supply fuel to the high pressure pump). I do not know which 'very early' models had a tank fuel pump.

Something worth noting. If you do hear a noise from the rear of the car (inboard of the rear wheel) - this may be cavitation or some other form of turbulence causing noise within the fuel filter. I have had a constant two-tone whine audible in the cabin in that area for the time I've had first A2 and realised recently it was actually more audible underneath the car in that exact area - I'm due to replace the filter and drain nut (using my re-engineered piece from @depronman) soon so hoping this may eliminate the issue.

Worth noting that on my project car I developed a starting problem after giving the car a fuel flush (Redex) - within a few days the car took more and more time to start suggesting air in the pipes which was eventually obvious as a fuel pump failure. Meanwhile, the (probably original) canister-style fuel filter also disintegrated so there was a dual fuel leak from both ends of the car.
 
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Thanks for all your help,
I’ve had a look at the fuel pump on the right of the engine and there is lots of old wet oil on it.
I’m sure that this should be clean.
 
Yep fairly sure you need to replace the tandem pump and gasket between it and the block. As you have an AMF ( I think ) replace the LUK pump with the far better Bosch pump. Your car does not have an electric lift pump in the fuel tank, so the tandem has to suck it all the way from the tank. As it wears it loses its ability to maintain suction in the fuel line and allows the fuel to drain back to the fuel tank replacing the fuel with air hence the long crank.
 
No you have internal wear in the tandem pump. To explain about the tandem a bit more. It is a mechanically driven by the cam shaft. It is a double unit that contains both the mechanical fuel pump AND also a mechanical vacuum pump to supply vacuum for brakes and various engine associated valves. Both pumps turn together on the same shaft. Being mechanical the fuel pump does wear out and as there is no check valve in the fuel line the fuel makes its way back down the supply line to the tank. Worn tandems are quite often the reason the last user sold the car. Not overly expensive but when owners skimp on servicing and maintenance there is no way they will pay the few hundred to replace the tandem on what they wrongly classify as a cheap runabout. If that is what they want then stick to Fiestas and Corsas rather than abuse an aluminium supercar!!!.
 
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