Provided you are absolutely certain the rubber fuel feed pipe to the tandem pump is air tight (and to be honest the only way I think you can be certain is to replace it with a new supple fuel pipe) then I think your diagnosis is correct. All I would add is, I would possible try a new gasket on the old tandem pump before replacing the actual pump. When the pump gasket leaks there is usually some sign of diesel leakage underneath the tandem pump. The gaskets are relatively inexpensive and quite easy to fit.Well it's been a while since I bathed in diesel, and my new drain plug arrived from Depronman today, so I had to fight off a bout of lethargy and go and play with this car again.
The Febi Bilstein Filters I got from ebay included all the O rings, so I put the two on the new drain plug and fitted it to the cap.
View attachment 121066View attachment 121065
With Paul's aluminium plug you don't have to remove it to do up the cap, which is way better than the Audi design.
With the filter back together, I bled the system from the return pipe in the hope that the starting problems I'd been having would be all gone No such luck unfortunately, she really didn't want to start at all now.
Next step was to test the tandem pump itself, so I hooked up a tank of diesel to the feed, and connected the return to an empty tank.
View attachment 121067
I've got much better hose clamps now, so I was confident of good connections. I tried bleeding the fuel through again with my vacuum pump, but even set up like this I couldn't rid the return line of air, or suck any significant amount of fuel through the feed pipe. When cranking the engine I could see a bit of fuel move up the feed pipe with each turn of the engine, but as soon as I stopped it returned back to the tank.
Despite lot's of bleeding and cranking, still nothing at all, so it's looking like it must be the tandem pump, it seems to have died altogether.
Before I go on the hunt for a new pump, I will wait and see if any of you clever folks on here have spotted some amateur mistake that I am making here, I would hate to buy one and it not be the actualy fault .
I quite like this diagnosis trick. Sounds like your "air in" leak is quite small. Even tiny air in leaks will affect how it starts. The tandem pump is very good at bleeding out air but only when the engine is running. The easy start has got the engine running and then the tandem pump is doing the bleeding. I think logically this means your tandem pump and it's gasket are good since the gasket is engine side of the pump bleeding mechanism.Some might not agree with me here and I was very reluctant to do this but I got some easy start yesterday and splitting the air intake near the MAF sensor I gave it a couple of small burst, I quickly grabbed the key and turned it, she fired up instantly and kept running with no problem.
I'm assuming that there must have been fuel in the tandem pump and feed lines.
I left it running for around 20 minutes, turned it off and left it for an hour, returning back I turned the key and she started up but did take around 7 cranks.
This afternoon I again turned the key and she started again but with only 4 cranks.
There is still a few bubbles in the clear tubing feeding the pump so there is still air entering the system but at least now I know the glow plugs are ok, the injectors are ok, and th e injector loom is ok.
Plus the cam sensor and crank sensor.
I've even taken it out for a spin for the first time in months around the small estate where I live.
Thanks for that, I like the idea of just trying a gasket..Provided you are absolutely certain the rubber fuel feed pipe to the tandem pump is air tight (and to be honest the only way I think you can be certain is to replace it with a new supple fuel pipe) then I think your diagnosis is correct. All I would add is, I would possible try a new gasket on the old tandem pump before replacing the actual pump. When the pump gasket leaks there is usually some sign of diesel leakage underneath the tandem pump. The gaskets are relatively inexpensive and quite easy to fit.
Well done for persevering and narrowing down the problem. You now know that the problem is air in the fuel and you have pretty much ruled out any leaks further up the fuel line.
Maybe a little positive pressure on the feed line (blow down it with you finger over the return?!) might elicit and external diesel leak???
I have got a brand new unused can of easy start that was in the glove box of my C1 scrapper, I've been reluctant to use it though.. Will ponder that cheers.I quite like this diagnosis trick. Sounds like your "air in" leak is quite small. Even tiny air in leaks will affect how it starts. The tandem pump is very good at bleeding out air but only when the engine is running. The easy start has got the engine running and then the tandem pump is doing the bleeding. I think logically this means your tandem pump and it's gasket are good since the gasket is engine side of the pump bleeding mechanism.
If @DaveySprocket were to try this and his started and immediately stopped again this could be a good way of pinpointing the tandem pump or more likely it's gasket.
Fully agree Paul.Go BERY easy with the easy start. Engines get addicted to it because is causes such a big bang the piston and con rod is compressed and actually shrinks This lowers the compression ratio and thus you get to a point that it will not start without the Big Bang easy start
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I've never used easy start - however, with my old student 2CV I was told by an AA guy once to put a squirt of WD40 into the carburettor to encourage firing whenever it had been left for a while in damp conditions and when the battery wasn't tip-top (or when the points / coil were damp which was reasonably often in Dundee!) and I did so now and again when starting wasn't going well but before the plugs got fouled with unburnt petrol - is the effect you describe with easy start much more violent than WD40?Go VERY easy with the easy start. Engines get addicted to it because is causes such a big bang the piston and con rod is compressed and actually shrinks This lowers the compression ratio and thus you get to a point that it will not start without the Big Bang easy start
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I've always believed that Easy Start burns very not. No idea if it's true, but that's why I've avoided it.I've never used easy start - however, with my old student 2CV I was told by an AA guy once to put a squirt of WD40 into the carburettor to encourage firing whenever it had been left for a while in damp conditions and when the battery wasn't tip-top (or when the points / coil were damp which was reasonably often in Dundee!) and I did so now and again when starting wasn't going well but before the plugs got fouled with unburnt petrol - is the effect you describe with easy start much more violent than WD40?
I would get the bosch one if its available and fits okay. But otherwise don't see any problem with either, they'll last 100k surely. Watch for import costs.Has anybody got any experience with these?
Pierburg Vacuum Pump Brake System VW SKODA SEAT 1.9 2.0 038145209 038145209A | eBay
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Pierburg should be pretty good quality, and it has the cast cover rather than steel..
I would get the bosch one if its available and fits okay. But otherwise don't see any problem with either, they'll last 100k surely. Watch for import costs.
Just make sure it is the tandem pump. It says for the 1.9/2.0 which I’m fairly sure have a in tank pump to supply fuel to the engine as such I did not think that had a tandem pump but instead a vacuum pump for the brakes
I may be wrong as I’m no expert on the 1.9/2.0 vag diesel engines
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It's curious that ebay and Autodoc list it as a brake vacuum pump, but it's the right part number and has the three connectors. The Bosch one is listed the same, so I guess it's just the way it is.Just make sure it is the tandem pump. It says for the 1.9/2.0 which I’m fairly sure have a in tank pump to supply fuel to the engine as such I did not think that had a tandem pump but instead a vacuum pump for the brakes
I may be wrong as I’m no expert on the 1.9/2.0 vag diesel engines
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