How to prime my 1.4 tdi after remaking the tandem pump

C

Cyril13013

New Member
Hi all, i’m french and i post here because you are A2s fans maybe you could help me…

I remove my tandem pump to change gaskets.
Now, i can’t prime my engine.
What i read is that there isn’t a pump into the fuel tank.
My starter begins to make bads sounds so if you have solutions to prime the engine and save my A2 with 326000kms i’ll be very happy…!
( i can’t pull my car because it is in an underground parking )

Sorry for my poor english, thanks in advance for your help guys
 
I always used to remove the fuel line at the INLET of the tandem but now remove the return line and use a hand held vacuum pump to suck the fuel all the way up into the tandem and then back to the return. As you are not disturbing the feed line there is less chance of it leaking.
 
audifan said:
I always used to remove the fuel line at the INLET of the tandem but now remove the return line and use a hand held vacuum pump to suck the fuel all the way up into the tandem and then back to the return. As you are not disturbing the feed line there is less chance of it leaking.
Click to expand...
Good idea ?
If i understood what you said, i let the inlet connected and i connect just the return output to my syringe to suck the fuel until the output ?
Does the tandem pump will be full of fuel after it ?
Thanks
 
That is correct. Connect to the tandem return with a length of tube to either a good syringe or a hand held vacuum pump until you have diesel. Quickly swap the pipe for the Audi return pipe and tighten the clamp back in place. If you do use vice grips please make sure you do not damage the rubber fuel pipes as that could induce air leaks.
 
audifan said:
That is correct. Connect to the tandem return with a length of tube to either a good syringe or a hand held vacuum pump until you have diesel. Quickly swap the pipe for the Audi return pipe and tighten the clamp back in place. If you do use vice grips please make sure you do not damage the rubber fuel pipes as that could induce air leaks.
Click to expand...
I think it is the best method ?
Tomorrow i’ll go to find a syringe or a hand held vacuum pump to do this !
Big thanks !
It is the best A2 forum ??
 
Just to clarify if not already. Connect a length of tube to the return port on the tandem and the other end of that to the syringe / hand held vacuum pump. Once fuel is through disconnect pipe from the tandem return port and refit the Audi fuel return pipe in its place.

1643758922570.png
 
audifan said:
Just to clarify if not already. Connect a length of tube to the return port on the tandem and the other end of that to the syringe / hand held vacuum pump. Once fuel is through disconnect pipe from the tandem return port and refit the Audi fuel return pipe in its place.

View attachment 90792
Click to expand...
Thanks for the picture.
I think i must to use the starter to make engine and pump turn. Whitout i think the fuel will be blocked by the system inside the pump.
What do you think about it ?
There is no direct link between inlet and outlet as the picture show us.
 
Just use the syringe or vacuum pump without turning the engine over fitted to the return port of the tandem. The return is completed by the internal fuel gallery inside the cylinder head so do not worry about that. All you are doing with the syringe or vacuum pump is generating the fuel return back to the tank ( about 90% of the diesel gets returned ) by creating a low pressure inside the head which will then draw the fuel from the tank through the inlet pipes and into the tandem. Once it has filled the tandem and the head gallery it will flow to the return side.
 
audifan said:
Just use the syringe or vacuum pump without turning the engine over fitted to the return port of the tandem. The return is completed by the internal fuel gallery inside the cylinder head so do not worry about that. All you are doing with the syringe or vacuum pump is generating the fuel return back to the tank ( about 90% of the diesel gets returned ) by creating a low pressure inside the head which will then draw the fuel from the tank through the inlet pipes and into the tandem. Once it has filled the tandem and the head gallery it will flow to the return side.
Click to expand...
Okay let’s do it tomorrow if i find a syringe or hand pump…
Thanks for your answers
 
Hi friends, just to say how i did it finally.
I found a syringe but it was broke and didn’t used it.
My brother came with a air compressor, took a rag and he push the air compressor « pistol » into the tank hole and put the rag to block the air inside.
When he blew air a little bit, i use the starter and after about 2 tests, the engine start !
Really easy method.

So, i want to thank all of you for your help.
Continue like that.
Thank a lot.

And sorry for my rough english…
 
@audifan
One simple question:
After you have diesel on the input line to the tandem pump - does it go back into the fuel tank?
The return valve is on the fuel return line in the fuel tank?(it prevents back syphoning on the return line only?)
 
On the Lupo 3L there is a non-return valve between the fuel filter and the tandem pump. On the A2 there is no such non-return valve. There is no point in having a non-return valve in the return line, mainly because it runs downhill and it doesn't matter if it is empty.

RAB
 
New pump and sealed lines, once you have the fuel through to the return the feed line will stay full of fuel.
 
The tandem pump will act as a non-return valve on the A2 but as soon as you disconnect the inlet line from the pump, the fuel will drain back to the tank, unless you squeeze the line flat. Even then, doing the latter will probably not be successful, given the wall thickness of the tubing. This won't be a problem with the Lupo 3L because it has a non-return valve between the filter and the pump.

So A2 owners know what to do!

RAB
 
RAB said:
On the Lupo 3L there is a non-return valve between the fuel filter and the tandem pump. On the A2 there is no such non-return valve. There is no point in having a non-return valve in the return line, mainly because it runs downhill and it doesn't matter if it is empty.

RAB
Click to expand...
I just took out the "thing" from the fuel reservoir- the one that does not have a pump in it but only the fuel level thingy. On the return line there is a built in return valve. And there is another "valve" that keeps the fuel in the small receptacle before going in to the tank.

So if you bleed out the system the return valve is at the end of the system for 1.2 tdi 2001 at least (right before going in the fuel tank).
I tried absorbing trough the pump but no luck...
I found a piece of rubber underneath (from the webasto installation) that was broken and...air got trough it.

So...if you are priming the system and you still get some air on the intake when priming...there might be some broken pipe along the route to the engine bay.
 
There's no point in having a non-return valve in the return line at the lowest point of the system! What is it going to do? Stop fuel flowing uphill, against the designed flow direction? Also it doesn't matter if the return line is empty. If there is one there, it doesn't serve any useful function, unlike the one between the filter and the tandem pump on a Lupo 3L.

RAB
 
RAB said:
There's no point in having a non-return valve in the return line at the lowest point of the system! What is it going to do? Stop fuel flowing uphill, against the designed flow direction? Also it doesn't matter if the return line is empty. If there is one there, it doesn't serve any useful function, unlike the one between the filter and the tandem pump on a Lupo 3L.

RAB
Click to expand...
I know what you are saying...but it has:))...i don't doubt you logic.
But in my case...for my 1.2 tdi from 2001 there is a return valve on the return line in the fuel tank (I hope I expressed the position corectly).

I started to test the system bit by bit because i had lots of air coming into the tandem pump input line.

Anyhow...i think i discovered my culprit.
The valve that is on the fuel filter. I tried to absorbe fuel right after the filter with a manual pump aaaand no luck.
The filter would not fill up(Does it have to be full when installing?...i do not remember doing this last time).

Any ideea what 057127247A valve is doing (the T valve that is mounted on top of the metalic fuel filter)? (as far as i know it should warm up fuel in the filter from the return line?..something like this?).
I just noticed a small crack in it...and if i try to push air trough it it seems to be very locked (and it does not matter if i press air from one side or the other even if it has an arrow on top regarding sense)

And by the way cyril explaind his symptoms....this might be the culprit in his case too. I tried presurizing the fuel tank with an air compressor and it worked for a bit. I will keep you informed if changing this stupid valve solves the priming issue.

@Cyril13013 any ideea what type of fuel filter you have? Did you change 057127247A on your filter?

@RAB this thing looks like it can act as another return valve....and again is on the return line....almost at the end. Not sure if it does...i will test on the new piece:)
057127247A .jpeg
 
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The valve is a regulating valve. The arrow on it should point towards the tank. Below 15degC, passage to filter is open, above 46degC, passage closed. Make sure that the O-ring for the valve is in the correct position.

Fill up the new filter with fuel before use.

RAB
 
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