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Discussion Starter #1
when the fuel tank gets to about a third full it becomes difficult to fire up.
air bubbles become visible in the clear hose when its running. i've changed fuel filter, plastic thing on top and even put non return valve on flow line. but hasn't made any difference. is there something around the tank that needs new seal or something .....any ideas?
 

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I don't know the answer mate but i'm watching the thread with great interest. My van starts first time on the button unless it's near the red line. It's far from empty at this point, atleast 60 miles to go but it takes a good 10seconds to start at this point. It's been the same for the whole 2.5 years i've owned it and got no worse but i'd still like to know why.
 

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Discussion Starter #4
thank god there is someone else out there, i changed glow plugs last year because this(wrong diagnosis)
 

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Very difficult to diagnose this one mate. But if it is when your tank gets low and not your imagination I would think it is something going on at the tank end. Maybe a hole in the pick-up or sludge in your tank blocking the pick-up and thus making your pump draw air in the lines somewhere.
If your Van is high mileage and you have used veggy oil or a diesel additive it will have cleaned your tank walls and brought a load of gunk to the bottom of the tank.
Make sure all your diesel line connections are tight especially around the filter, also when you changed the filter did you fill it with diesel before connecting the lines ? this could be causing an air-lock.
At least that's a few thing to try for you mate even if it's not a definitive answer.
 

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have you checked the pick up tube

or obvious answer is your fuel guages are out of calibration and dont trust it - keep it filled up. . . . .
 

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Hi There,
I have had this problem and it was frustrating the hell out of me for a while. I too saw bubbles in the clear line when running and very hard to start when the tank was low. I pulled vacuum on each part of the fuel line and got bubbles and fuel all the way to the tank.

When I removed the tank sender/pickup assembly and took it apart I found the plastic part of the pickup had shrunk and cracked and was allowing the pump to suck air at low fuel levels.
This can be fixed with fuel hose and straight pipe but later I relented and bought a new pickup assy. (about $240 in Australia).

I remember when I was in the middle of the repair that I found no answers on the forums. I was surprised as I thought with so many T4s around somebody somewhere must have had the same problem before...

Good luck

Cheers,
FarmSyncro
 

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Discussion Starter #10
cheers farm syncro, i have just been to my local vw garage and got printouts of tank and fuel sender assembly. i had a feeling it was something to do with a tank conponent cos of the low fuel tank issues( about a third full when problems occur,same as you?). i'm the same as you regarding no one else having this problem. i have been doing not many miles lately,so i have had a low tank for a while so i persume things can 'dry out',i,e seals etc.
how do you access the sender ,is there a panel in floor of van?
its amazing someone from other side of the world can answer my problems, the beauty of the internet i suppose!
cheers , dan
 

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I too have the same low fuel bad start with my T4. I have not spent any time wondernig the whys and wherefores (perhaps I should!) but I get to just above the Red mark and that's where the fun starts. Takes an age to start, and also if I corner to quickly or going up an incline the van strugles like hell, blows out clpoud of white smoke and then settles back down.

As soon as I top up, she is as good as gold! Starts first turn of the key any weather, and performs as normal.

Now I try to avoid letting the tank get that low just to avoid these problems, having read some of the posts here I may have to have a think about actualy investigating the cause instead of just giviving a good ignoring, but that will have to wait now until the spring when it's lighter and a tad warmer to do such maintenance!

Cheers!

T4Druid
 

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Hi,I have a 2.5tdi and I have problems when my tank is below a third full,when I'm on a steady incline say a mile long my power will dissapear and stall,I will crank it for 10 seconds then it will fire up again, I'm assuming it's the pickup pipe sucking air in,can this be changed without tacking the whole tank out?
 

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Discussion Starter #15
yeah like previous people have posted ,theres an inspection hatch in the floor by seats,apparantly.
 

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hello Dan I have same problem and have bought a new fuel sender unit for my tank ,(95 euro) .When my tank gets down to 1/3 full she wont start .It has wrecked my head for a year now so have just kept it full ! I will fit it early next week and will post results here .
 

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Hi all bad start fans,
Dont anybody take my word for it. Test for yourself.
I used a syringe to pull fuel at each join of the fuel line. As I was pulling fuel through I could see in the syringe half liquid and half bubbles. I was able to trace this back to the fuel tank pick up at the top of the fuel tank.
To access this, remove the passenger seat (LH seat), lift the carpet or rubber mat (in my case this involved removing the LH door step trim and other trim clips, gear stick knob and boot and other stuff) and remove the fuel delivery line off the tank pickup assembly. I cannot remember which one (of two) connections is the delivery and which is the return line - but there must be some clue in front of you.... Normally the delivery line is bigger, sometimes there is an arrow stamped on the pick up.

When I pulled a vacuum here with the syringe I got fuel and bubbles like before.
When I removed the pickup assembly from the fuel tank and took it apart I found cracks in the plastic section of the pick up tube. Initially I fixed this with straight 5/16 tube and flexible fuel hose but, I was worried about the compatability of my fuel hose with diesel fuel. I know it is OK with petrol but I didnt know about diesel.
This fixed the problem and I could pull neat fuel up through the pick up. Not wanting to revisit this again, possibly on the side of the road, I relented and bought a new pick up assy.

I hindsight I suspect this problem may have existed when I bought the van only a few months before. When the then owner took me for a drive we did stop and fill the tank on the way - I did think this was a bit strange at the time... What ever happened to honesty - even within the VW community. This would never happen with an air cooled "kombi"- normally a test drive is only as long as it takes to tell the prospective buyer all the problems!

Have fun,
Farmsyncro
 

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Hi gentlemen , I had same problem with my 2.5 and replaced the fuel sender unit in the tank. Its an hours work and the part cost me 95 euros about 80 pounds. It solved the problem 100% and the sender unit had some small cracks in it allowing air in .
 

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Hi guys,
i have the same issue with My van... nad have been looking around for ages. Can you tell me, did it work when you change the pick up unit??

would be great to know so that I know where to start.

Thanks,
 

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Why didn't I look here first?
Yes I've had the same problem for about 2 or more years but only managed to work out it's coincidence with lower fuel levels, & the therefore obvious cause, a year ago. The penny sometimes takes some time to drop.
Now because I'm "old school", from the days when the interior gubbins of cars & vans looked more like bits of Meccano, I had assumed it would be a 3 quid bit of pipe going down into the bottom of the tank that had corroded or perished, allowing air to be drawn in, so I went to my local VW van dealer & the helpful spares guy let me have a look on his ETKA database & gave me a copy of the diagrams for the sender unit as well as the fuel line assemblies. Well at the moment, 70 odd quid plus VAT, for a new unit is a bit is a bit of a shocker but I'd pay it if I thought a repair to the old unit was a waste of time.
The real horror story though could be doing the work. Is anyone that has replaced one prepared to write up some quick instructions & post them on this thread? Is there a floor panel that allows access? My van (97 SWB 1.9tdi 800 Special) is ply lined & lifting the floor sheet would involve removing the side panels too but I'd do it rather than dropping the tank if that was a nightmare.
All available advice, instructions & drawings would be most welcome.
Pilch
 
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