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Lift pump fault

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PETE.T28 View Drop Down
Yardie
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    Posted: 22 Jun 21 at 22:05
Hi all 
Not been on here for a few years life been getting in the way. Have a  174 09 plate and have a question. Just changed the tandem pump as it appeared to be leaking and finding it hard to prime the fuel system. The filter is a 2 pipe so I disconnected the return pipe at the elbow fitting near the filter and put a container underneath, the idea was to prime the system using cycling the ignition on and off. After 10 or so goes I thought I would check the container see if any fuel was coming out of the elbo but found a pool of diesel under the van....this had been squirting out of the brown pipe that goes to the tank and should be the return. Am I missing the trick or has the lift pump failed as well. What's odd is disconnecting the black tube (flo) at the filter also gives a flow of fuel when priming weird eh!
Any thoughts anybody.

Pete
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 22 Jun 21 at 23:16
Hi Pete,  A two pipe fuel filter on a 174 is a new one on me. Confused  They probably changed things on the later vans.  If you can post some good pics here it might help.  I wasn't quite clear form your description but here's how it works on the old system if it is any help.  

The fuel from the low pressure pump in the tank comes up to the fuel filter, through the filter and then on to the tandem pump.  The pressure gets stepped up by the tandem pump then it arrives at the PD injectors and the real pressure increase happens as the camshaft squashes the injectors to inject the fuel as timed by the ECU.  The injection pressures are mind boggling!  The fuel is hot by now and goes back to the fuel filter (passing by a fuel temperature sensor) then through a fuel cooler radiator (easily visible under the floor) and then on back to tank.  

If you only have two pipes at the fuel filter neither of them can be a return.  Either you have no fuel cooler (which seems unlikely since the tank is plastic) or it must be plumbed in a different way on your later 174.  Perhaps they have decided the fuel doesn't need to go via the filter again on the way home.

If you disconnect the supply from the tank pump at the fuel filter inlet connection, you should get a short squirt of fuel for each cycle of the ignition.  If you don't get this I would say the tank pump is faulty or there is some restriction in the pipe.       


Edited by T5 TDI - 22 Jun 21 at 23:24
2004 2.5 174
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 21 at 06:41
Cheers mate. 
Yep it is different to older vans only two connections on the fuel filter.
 The return pipe is routed up near the filter then connected to the hard pipe 'brown' return line to cooler then tank. My understanding is the return goes into the lift pump lid and is  just a short pipe dropping fuel back in the tank. 
I just can't understand when priming it sends fuel up the flow and return when both pipes are disconnected in the engine bay....
Also there are less relays under the battery tray than my previous vans so obvious made a few changes here and there.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 21 at 09:33
What engine code is yours?  The online parts manual shows the 4 pipe filter for the 2009's with these engine codes.  Yours couldn't have been altered could it?    

Volkswagen Transporter 2009fuel line 1.9ltr. 2.5ltr. diesel eng.+ AXC,AXB,BRR, BRS AXD,AXE,BLJ, BPC,BNZ

   
2004 2.5 174
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 23 Jun 21 at 17:44
poss a bpc would have to check. It all looks factory. Tps supplied the filter off the reg so guess it's right..... Managed to get it primed and running by blocking off the return pipe to the tank and beading air from the elbow which is just after the temp sensor. Just kept priming with they key until I had a good flow of fuel. Connected her back up and she started on second turn. I think there is a problem with the lift pump but as it's not pumping whilst the engine is running it's not critical

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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jun 21 at 11:36
I have read of a couple of other cases where there was air between the tandem pump and the injectors.  That should just sort itself out but apparently that doesn't always work.  

It does sound like they have swapped the the route of the return flow pipe on late vans.  I can see the advantage of returning the hot fuel via the filter to keep it from waxing in very cold temps but perhaps it's not deemed necessary any more for some reason.  


Edited by T5 TDI - 24 Jun 21 at 22:30
2004 2.5 174
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jun 21 at 19:03
the previous owner had years of breakdowns and the garage could never fix it. I only know this as I bumped into a mate of his and he told me all about it. I guess that's why I bought it so cheap. 4k for a black combi sportline did seem a bit of a gift at the time....
Anyways I wonder if the garage replaced the fuel sender at some point and got the  flow and return mixed up and he's had problems ever since.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 24 Jun 21 at 21:37
You can see what the fuel temp sensor is recording live with VCDS so you can check if it is doing what it should.  I will post the the numbers here of the groups to look at when I get a chance.  Even if it doesn't mean that much to you it might help someone else in the future. :)   

I can't help much with the flow and return because I haven't seen the two-pipe version but I would find and check the flow from the pump and see what it does.  From your description it sounds like the tank pump is pumping fuel through both flow the and return pipes which must be wrong.

Edit- The data from the fuel temp senor is found in VCDS at group 007 in the first field.  It should be a  fairly close match to the coolant temp, intake air or ambient temp with a stone cold engine.  After that it should climb to a maximum of around 90 degrees C.  A poor fuel temp sensor can affect starting and running but a quick VCDS check live from cold could soon eliminate it as a culprit for any problems rather than just chucking in parts since it's not a very common fault.  


Edited by T5 TDI - 24 Jun 21 at 22:34
2004 2.5 174
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 17:45
I have vcds lite not sure if it will run that test. The result of fitting new tandem pump...no change van starts ok and runs fine until normal operation temp is reached then cuts out and is a pig to start again. . No DatC''s.   I have a spare used fuel temp sensor that I could swap out. After that I guess I should be looking at crankshaft or cam sensor or temp sensors.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 18:05
Apears vcds lite will measure fuel temp can I check live with engine running?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 19:53
Okay Had her running from cold to just below operating temp on my drive with vcds running until she cut out....
Fuel temp rising slowly always about 10 degrees lower than coolant temp.
Lumpy running on tickover smoothed out with higher revs.
At tickover
Inj 1 -2.31
Inj 2 -0.75
Inj 3 -0.38
Inj 4 -1.29
Inj 5 +plus 2.99
Is it likely I need a new injector loom?
Still no fault codes.....


Edited by PETE.T28 - 28 Jun 21 at 20:09
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 19:57
Yes if VCDS lite lets you.  'Measuring Blocks' is the live data from the various sensors, you can't do any harm by scrolling around and having a look in measuring blocks but don't hit the 'switch to basic settings' button, stay with the live data.  

If you're sure that your fault is definitely temperature related I would investigate all temp groups from cold as the engine warms up.  If 062 is available, have a look there.  If it is, you could log the results from cold and see if anything unusual is happening when your fault occurs.  (VCDS lite might not offer this though).

062,0,Engine Cooling 
062,1,Coolant Temp. (G62),Engine Coolant
062,2,Coolant Temp. (G83),Radiator Outlet
062,3,Ambient,Temperature (G19)
062,4,Intake Air Temperature (G42)

Even if VDCS lite doesn't offer the logging option you can still just watch each sensor from cold and see if the numbers look consistent and sensible. 

 Edit- Crossed post..


Edited by T5 TDI - 28 Jun 21 at 20:42
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 21:22
Originally posted by PETE.T28 PETE.T28 wrote:

Okay Had her running from cold to just below operating temp on my drive with vcds running until she cut out....
Fuel temp rising slowly always about 10 degrees lower than coolant temp.
Lumpy running on tickover smoothed out with higher revs.
At tickover
Inj 1 -2.31
Inj 2 -0.75
Inj 3 -0.38
Inj 4 -1.29
Inj 5 +plus 2.99
Is it likely I need a new injector loom?
Still no fault codes.....

Where are you seeing those figures?  Group 13/14 I presume?  If so, the figure for inj 5 does look a bit high.  There is nothing to worry about with a few small plus figures on the 2.5 's but a set of minus figures are more common for a healthy system at idle with no faults but I wouldn't replace anything (unless it's very cheap/easy) on that basis.  

If it helps, here are my my figures from group 13 (and 14 for cyl 5) from a while back (2.5 AXE ) at idle with a not quite fully warm engine.

Inj 1 -071
Inj 2 -054
Inj 3 -079
Inj 4 -009
inj 5 -016

I think I would start with a new fuel filter primed with neat injector cleaner if you haven't tried that already.  Otherwise maybe get injector 5 cleaned and tested by a diesel specialist.  I haven't personally seen the injector loom fault but most that I have heard about cause clear misfires.  Your call though! Tongue    




Edited by T5 TDI - 28 Jun 21 at 21:32
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 21:41
Cheers for all the advice bud. I put a new filter in when I did the tandem pump and mixed s bit of injector with fuel in th filter the rest of the bottle went in the tank. This fault was random but now becoming frequent every time it's run infact. The van has 260k miles on her so  bit leggy.
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 21:53
blocks 13 and 14 at 1500 revs
1  -0.71
2 +0.33
3 +0.42
4  -0.49
5 +0.42
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 28 Jun 21 at 21:58
just an update when it cut out on the drive whilst getting the readings she was almost up to operating temp. Now she's stone cold and not starting, I'm sure if I keep cranking and give it some gas it will start eventually. But it does seem more like a fuel starvation problem. The lift pump in the fuel tank does..I'm assuming it only pumps when you first turn the key to start the van and not at any other time?
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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 21 at 08:56
I'm not sure about whether the pump should be running after priming.  The VW description on SSP 305 says 'The electrical fuel pump in the tank serves as a pre-supply pump, and pumps fuel to the fuel filter.' which is a bit of an ambiguous way to put it.  

I remember mine runs for a second or so and then switches off once primed.  It's possible that it restarts once the engine is going but I don't know for certain.  

I take it your fuel is a good normal clean colour and not grey by being contaminated with engine oil?  Also that the engine oil doesn't smell of diesel and is not high on the stick.


Edited by T5 TDI - 29 Jun 21 at 09:32
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 21 at 09:51
It's a weird one when you search it on the Web most say the pump runs all the time the engine is running so maybe that's where the fault lies as it's doing strange things by pumping up flow and return.
I guess I'm just going to have to swap it out..



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Post Options Post Options   Thanks (0) Thanks(0)   Quote T5 TDI Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 21 at 10:09
Originally posted by PETE.T28 PETE.T28 wrote:

....as it's doing strange things by pumping up flow and return.




That part is very odd and is probably enough reason to take the pump out and test it at least.  It is a tank out job though.  
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Post Options Post Options   Thanks (0) Thanks(0)   Quote PETE.T28 Quote  Post ReplyReply Direct Link To This Post Posted: 29 Jun 21 at 15:51
yep is a pita but Ive dropped the tank on 3 T5's now so should be ok.

Edited by PETE.T28 - 29 Jun 21 at 15:51
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