AHU fuel pump problem

[hotpod]

I have almost finished an install of an AHU tdi to my camper and i had to strip and clean the fuel pump as it wasnt pumping. it would just about tickover but that was all. it had sat for two years with neat 100% veg biofuel and the pump vanes and various other bits had stuck.
anyhow, the clean up was fairly straight forward ( so we thought) and we put the pump back in this evening.
it is now pumping like a beauty....but no fuel is making it to the injectors. it is as if the fuel stop solenoid hasnt engaged, but we have established that that is working fine so i can only guess that something at the distributor end of the pump hasnt gone back together as it should.
its a mystery to us as we were extremely careful to replace everything in its proper place.
anyone had this before or got any ideas as to whats wrong?

[syncroandy]

Hi chap, your message isn't clear, is the stop solenoid not working (getting 12v but not working), or is it not getting 12v ? If the latter, check the ECU can see the crank turning, it won't operate the solenoid until it does,

[hotpod]

the stop solenoid works fine off the car and it gets power fron the ecu when the engine is cranking, so we are assuming thats all good.
we almost didnt bother checking it as it worked properly before we took the pump off and we didnt dimantle the distributor part of the pump. the external parts of it did come apart and were cleaned,the springs etc, but went back on exactly how they came off.
my only guess at this stage is that there is some sublety to putting it back together that i somehow missed. like something able to go on 180 degrees out or something, but there seems to be only 1 way for everything to go back together and even in that case, we would presume that fuel would get to the injectors at some point rather than not at all in this case.

[hotpod]

i think the problem is solved...although i cant test it now till my starter is fixed ??@:~}{+ why it chose that moment to fail is beyond me.
anyhow, having read lots of forums and pump manuals, the subtlety i missed was that the cam plate can actually insert two ways. if you choose the wrong way, the high pressure pump shaft goes in 180 degrees out and no ammount of swearing will convince fuel to come out of the distributor.
it was remedied with the pum in situ and i am extremely confident that that is the problem. i just wont be able to tell you for certain till i fix the starter.
i might just treat him to a new one.
will let you know asap

[hotpod]

sarter was stripped and cleaned and had new brushes and now spins like a beauty.
and there is definately fuel getting to the injectors
but not even a hint of firing.
running out of ideas now but the only thing thats changed is the pump so presumably still something wrong in there

[hotpod]

the saga continues.
turns out it was the right way round originally, so something else was blocking the fuel. we turned it around again today and he will start but not even tickover and if i press the throttle i get one big rev and then no more response. seems like still a fuel blockage in the high pressure end unless any other part of the pump gives those symptoms.
will test it on vag com tomorrow as there is an engine fault showing on the glow plug light.
if anyone has any ideas to throw about it will be much appreciated.
getting a bit cross with it now. i just want to drive my camper again.

[mazz]

I'd say your pump is toast, as a rule if you leave any fuel pump standing with the usual diesel/ water mix it corrodes cam plates, or weakens one of the two cam plate springs,
Ether remove pump and send it off for test and repair ( my first choice ) or buy another used pump, but beware whatever you buy is going to be at least 14years old and if left standing is probably no better than yours

[hotpod]

nothing corroded in there. it had all been coated in a thin toffee like protective film from the 100 % veg biofuel it was running on when i got it. i have half a feeling it might have something to do with the high pressure solenoid valve on the bottom of the pump. when i took it out and changed the o rings, i concluded that it was merely a temperature sensor or similar so didnt give it much thought, but having read up on it, it is far more critical to the correct running and timing of the pump.
i think i have one on another pump ( with actual diesel in it) which i can try.

[mazz]

That lower solenoid adjust pump timing so should not really cause starting issues, is there plenty of resistance when rotating pump by hand, it should be just about possible to rotate by hand if it's any good

[hotpod]

i actually didnt try it myself, the chap whos helping me is a helicopter engineer so wasnt at all phased by stripping down a tdi fuel pump. but this has him stumped too.
i drove the car the engine was out of two years ago and it was running beautifully which is why i used that engine. i didnt really think of the consequences though of leaving it sat for so long with biofuel ( converted used veg) in the pump. to be fair, it was meant to be a 3 week job...

[hotpod]

all sorted and driving well.
i found a local scrapyard with a fresh passat. the pump looked the same but had a different letter on the end of the part number. since it was only £20 i risked buying it anway and then phone MV engineering to ask if it would work. (its off a 110 hp AFN/AVG ) he said that the cams are slightly different but should work fine.
hes right, it does.
passed MOT on friday, and only 3 whole years since the gearbox packed up, its back on the road