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Fuel air lock 19tdi


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#1 Rushmore

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Posted 24 January 2021 - 02:25 PM

Anyone know how to bleed the air out of my fuel system on my 19tdi it was running fine till it ran out of fuel


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#2 gerrywac

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Posted 24 January 2021 - 03:34 PM

You dont say what age and engine but the PD diesels with the in tank fuel pump Mk4late snd Mk5 should self prime and self bleed with a bit longer cranking of the starter.
Turn the key to first position for several seconds and the fuel pump will fill the filter, them crank and it should fire within a further several.
Done it a few times with my 07 1.9TDI (BXE PD) over several years and never needed anything more

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#3 Rushmore

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Posted 24 January 2021 - 04:18 PM

You dont say what age and engine but the PD diesels with the in tank fuel pump Mk4late snd Mk5 should self prime and self bleed with a bit longer cranking of the starter.
Turn the key to first position for several seconds and the fuel pump will fill the filter, them crank and it should fire within a further several.
Done it a few times with my 07 1.9TDI (BXE PD) over several years and never needed anything more

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yes it’s a 2008 bluemotion tdi and it started up then died after a few minutes running time I’ve got a mechanic coming over tomorrow who said that it’s probably the fuel filter blocked due to the car being quite old now and it’s probably got air in the system thing that baffles me is you can hear the fuel pump go on then nothing no more fuel pump I’ve tested the relays and they are fine I’ve even hard wired the pump and it’s working I’m thinking it might be a cluster issue as I’m having to lock the drivers door wait and then it will start what do you think any ideas


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#4 gerrywac

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Posted 24 January 2021 - 05:42 PM

When the car is unlocked and the door opened the low pressure pump in the tank should turn on and run for a while to fill the filter bowl and then stop until you turn the ignition to the first position when it will start running again whilst you start the car. Whilst running it circulates fuel to the filter bowl and any surplus returns to the tank. I've had mine 10 years, done 4 filter changes and dach time theres been next to no solid debris in the bowl or the filter distorting but I've always used Mann OEM quality filters.
The tandem pump on the engine sucks fuel through the filter and delivers it at medium pressure to the PD injectors which inject it a very high pressure to the cylinders,surplus fuel returns to the filter bowl and then back to the tank.
The tandem pump generates quite a lot of suction and pressure circulating fuel and this is what should normally purge any air very quickly by forcing it into the filter bowl and then the tank. If the filter were totally blocked nearly completely then in theory it would cause fuel starvation stopping the engine but I've never heard of a case.
The fuel filters are large and if OEM of very good quality and even if changes were neglected should cope with a large amount of diry and debrid and contine to pass enough fuel so the engine continues to run properly for a long time. Contiued neglect might lead to gradual blockage and fuel restriction but you would normally experience low power at speed and slow acceleration when accelerating rather than engine stoppage.
Before getting a mechanic out it might be worth getting an OEM quality filter and doing a change yourself
Any debris from fhe tank should be readily identifiable as it is blocked by the outside of the filter and falls and is collected in the bottom of bowl where it remains until removal during service.
I have heard of the odd occasion in other makes where a small poor quality filter has bern fitted and collapsed blocking fuel flow almost entirely but not on a VW.

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#5 Rushmore

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Posted 24 January 2021 - 07:04 PM

When the car is unlocked and the door opened the low pressure pump in the tank should turn on and run for a while to fill the filter bowl and then stop until you turn the ignition to the first position when it will start running again whilst you start the car. Whilst running it circulates fuel to the filter bowl and any surplus returns to the tank. I've had mine 10 years, done 4 filter changes and dach time theres been next to no solid debris in the bowl or the filter distorting but I've always used Mann OEM quality filters.
The tandem pump on the engine sucks fuel through the filter and delivers it at medium pressure to the PD injectors which inject it a very high pressure to the cylinders,surplus fuel returns to the filter bowl and then back to the tank.
The tandem pump generates quite a lot of suction and pressure circulating fuel and this is what should normally purge any air very quickly by forcing it into the filter bowl and then the tank. If the filter were totally blocked nearly completely then in theory it would cause fuel starvation stopping the engine but I've never heard of a case.
The fuel filters are large and if OEM of very good quality and even if changes were neglected should cope with a large amount of diry and debrid and contine to pass enough fuel so the engine continues to run properly for a long time. Contiued neglect might lead to gradual blockage and fuel restriction but you would normally experience low power at speed and slow acceleration when accelerating rather than engine stoppage.
Before getting a mechanic out it might be worth getting an OEM quality filter and doing a change yourself
Any debris from fhe tank should be readily identifiable as it is blocked by the outside of the filter and falls and is collected in the bottom of bowl where it remains until removal during service.
I have heard of the odd occasion in other makes where a small poor quality filter has bern fitted and collapsed blocking fuel flow almost entirely but not on a VW.

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yes I’ve ordered a new filter and I’m going to have a look myself tomorrow


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#6 gerrywac

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Posted 24 January 2021 - 07:49 PM

yes I’ve ordered a new filter and I’m going to have a look myself tomorrow


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Easy enough job. Remove the engine cover and set aside and then the torx screws on the lid perimeter and prise up and swing it away.
Remove the filter slowly allowing the diesel to drain into the bowl. Inspect, if it"s good the pleats should be largely even and appear much like the new filter, colour aside. If its blocked there may be warping and distortion.
If there's debris visible in the bowl remove the diesel and wipe clean, otherwise you can leave in place and replace the filter.
There's no need to top up with fuel.

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#7 Rushmore

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Posted 24 January 2021 - 11:47 PM

Easy enough job. Remove the engine cover and set aside and then the torx screws on the lid perimeter and prise up and swing it away.
Remove the filter slowly allowing the diesel to drain into the bowl. Inspect, if it"s good the pleats should be largely even and appear much like the new filter, colour aside. If its blocked there may be warping and distortion.
If there's debris visible in the bowl remove the diesel and wipe clean, otherwise you can leave in place and replace the filter.
There's no need to top up with fuel.

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Thanks buddy.


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#8 mur3633

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Posted 25 January 2021 - 08:19 AM

Try to avoid getting fuel so low. Lift pump overheats and become weak. I had that problem and now I avoid to go under 1/4 of fuel tank.


Buy some fuel injector cleaner additive and fill new filter with it.
Liqui Moly is maybe the best brand.

Edited by mur3633, 25 January 2021 - 08:22 AM.

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#9 Rushmore

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Posted 26 January 2021 - 01:11 PM

I’ve got it running and after half an hour it cut out refusing to start the oil light came on and the glow plug light came on just before it cut out any ideas please


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#10 Rushmore

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Posted 26 January 2021 - 01:13 PM

I’ve got it running and after half an hour it cut out refusing to start the oil light came on and the glow plug light came on just before it cut out any ideas please


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also I’ve replaced the wiper stalk as the wipers come on when you drive but refuse to work while the car is stationary I’ve replaced the motor and it’s doing my nut now.


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#11 mur3633

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Posted 26 January 2021 - 01:27 PM

I’ve got it running and after half an hour it cut out refusing to start the oil light came on and the glow plug light came on just before it cut out any ideas please


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Tandem pump?
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#12 Rushmore

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Posted 26 January 2021 - 01:29 PM

Tandem pump?

is that in the back of the car under the seat


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#13 gerrywac

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Posted 26 January 2021 - 02:07 PM

is that in the back of the car under the seat


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No the tandem pump is on the gearbox end of the cylinder head driven off the end of the camshaft. Its called a tandem pump because its two pumps in one, a medium pressure fuel pump for the engine and a vacuum pump for brake servo, turbo and EGR.
The fuel pump draws fuel from the filter feeds it to the injectors and surplus back to the injectors.

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#14 Rushmore

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Posted 26 January 2021 - 02:16 PM

No the tandem pump is on the gearbox end of the cylinder head driven off the end of the camshaft. Its called a tandem pump because its two pumps in one, a medium pressure fuel pump for the engine and a vacuum pump for brake servo, turbo and EGR.
The fuel pump draws fuel from the filter feeds it to the injectors and surplus back to the injectors.

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ok thanks I’ll have a look I’ve opened up the fuel filter and it’s dry but my pump is working so I think the guy I bought the car from had put something in the tank to be spiteful as it was a non runner and I changed the fuse and it started up first time but I didn’t take the car there and then a few nasty scratches and dents appeared on the car also the interior mirror and fog lamps were removed


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#15 northpole

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Posted 27 January 2021 - 01:27 PM

uhmmm, that is nasty...  if the fuelfilter is dry you might have a problem with the intank pump...  and usually this problem is found on the early mk4 tdi's... it  is a relaythat has burned out... not so much on the mk5's as they have the  revised relay (it's relay 109 and should be black if it is the gray one replace it asap). Once that relay burns out the tandem pump is left to suck the fuel up through a non working restrictive liftpump... it will start at first but will die after a while as it can't get enough fuel in..

 

so if you turn the key to position 1 and you don't hear a priming noise coming from the back (it's right behind the os near passenger seat) than it possibly is the relay but you can check it with a multimeter on the cables of the lift pump, it should have a full 12v on there as soon as you turn the key.      


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#16 Rushmore

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Posted 27 January 2021 - 01:39 PM

uhmmm, that is nasty... if the fuelfilter is dry you might have a problem with the intank pump... and usually this problem is found on the early mk4 tdi's... it is a relaythat has burned out... not so much on the mk5's as they have the revised relay (it's relay 109 and should be black if it is the gray one replace it asap). Once that relay burns out the tandem pump is left to suck the fuel up through a non working restrictive liftpump... it will start at first but will die after a while as it can't get enough fuel in..

so if you turn the key to position 1 and you don't hear a priming noise coming from the back (it's right behind the os near passenger seat) than it possibly is the relay but you can check it with a multimeter on the cables of the lift pump, it should have a full 12v on there as soon as you turn the key.

yep no power thanks buddy


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#17 adam-

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Posted 28 January 2021 - 08:37 AM

changed the fuse and it started up first time

 

Fuses don't blow for no reason...


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#18 northpole

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Posted 28 January 2021 - 12:53 PM

jup you need to find out why the fuse blew... it could be the before mentioned relay or somehow the rear is wet causing a short in the cables...  or to much resistance because of rust on the connectors to the liftpump... so look a little further than thinking it's solved by replacing the fuse. 


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#19 gerrywac

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Posted 28 January 2021 - 05:29 PM

Fuses do actually deteriorate with age and may just blow for no obvious reason.
It's worth a quick look round the relay and fusebox for signs of corrosion or loose connections but as long as it doesn't blow again with a correct value replacement then there's no real need to investigate further.

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#20 Rushmore

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Posted 28 January 2021 - 07:13 PM

Fuses don't blow for no reason...

yes the idiot that owned the car before me jump started it with using a protector and blew the fuse I’m taking the tank pump out tomorrow as I think it’s blocked due to crap in the tank


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#21 Rushmore

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Posted 28 January 2021 - 07:13 PM

yes the idiot that owned the car before me jump started it with using a protector and blew the fuse I’m taking the tank pump out tomorrow as I think it’s blocked due to crap in the tank


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out


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#22 ttg4l

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Posted 28 January 2021 - 08:08 PM

Take a look at the plug for the fuel sender unit, make sure there's no coolant in there. The ground is shared with the coolant temp and level sensors, which can potentially leak coolant into the loom and migrate along causing a short.


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#23 Rushmore

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Posted 29 January 2021 - 12:13 PM

Take a look at the plug for the fuel sender unit, make sure there's no coolant in there. The ground is shared with the coolant temp and level sensors, which can potentially leak coolant into the loom and migrate along causing a short.

will do thanks


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