Air in fuel system

Hugh · Nov 9, 2013

I am having huge problems with air in the fuel system of my Td5.

The car has had:

A new FPR
The fuel injector washers replaced
New fuel filter
Air flow meter
One way valve on tank
New fuel pump (x 2)
Every fuel line checked
ECU data checked
Injector loom checked for oil (all clean)

As soon as the ignition is turned to the second position the fuel pump whines like mad for three seconds or so and air can be felt/heard rushing through the fuel filter. Turn the ignition off and it can be felt/heard running back through the filter in the opposite direction.

Its a blighter start, taking about three goes and seeming to start on a couple of cylinders at a time before they all run. The air is worst when its been left for a long time but even after a short stop (at the petrol station, etc.,) it is a pain to start.

Running the fuel through a loop of clear pipe has been mentioned - any ideas how would I attempt to do this?

If the air is noisy through the filter does that help to track it down?

If I park nose up or nose down, would that help to track it down?

I'm running out of ideas... ...do any others come to mind? :confused2:

thebiglad · Nov 9, 2013

Hugh said:
I am having huge problems with air in the fuel system of my Td5.

The car has had:

A new FPR

The fuel injector washers replaced

New fuel filter

Air flow meter

One way valve on tank

New fuel pump (x 2)

Every fuel line checked

ECU data checked

Injector loom checked for oil (all clean)

As soon as the ignition is turned to the second position the fuel pump whines like mad for three seconds or so and air can be felt/heard rushing through the fuel filter. Turn the ignition off and it can be felt/heard running back through the filter in the opposite direction.

Its a blighter start, taking about three goes and seeming to start on a couple of cylinders at a time before they all run. The air is worst when its been left for a long time but even after a short stop (at the petrol station, etc.,) it is a pain to start.

Running the fuel through a loop of clear pipe has been mentioned - any ideas how would I attempt to do this?

If the air is noisy through the filter does that help to track it down?

If I park nose up or nose down, would that help to track it down?

I'm running out of ideas... ...do any others come to mind? :confused2:

I think the first thing I would be doing is a full bleed, as there has been lots of work on the fuel system there's every chance of air.

This is how I would do it:

1. Make sure you have a fully charged battery before commencing;

2. Lower the drivers door window, get out of the car and close the door, then turn the ignition to pos II where the pump will start working;

3. Leave it running for up to 3 mins or until the pump stops, whichever is the sooner;

4. Now try to start the engine - is it any better? If not replace the "bleed valve" in the filter housing.

Dave

Hugh · Nov 9, 2013

Thanks Dave, that appears to be a fix!

The purge procedure has been our stock-in-trade recently. I took the air bleed valve out and the filter was black (presumably from where the injector seals had leaked and some carbon had got in the fuel).

I prised the valve apart, used some solvent and a cloth to clean the filter and put it back. There was no noise at all when I re-purged it (surprising since I had let fuel out) and it started first turn of the key!

I cant confirm it as 'fixed' until tomorrow morning, but it is already much better.

My theory is that the screech from the pump / filter was air and fuel being squeezed past as the filter was blocked, like a clarinet reed.

I'll let you know what happens tomorrow morning - its always worst after standing still for a night - but a big thanks!

Hugh · Nov 10, 2013

It starts much, much better now, but with a second or so of a noise like a cat being strangled when the ignition first goes on.

Good enough!

Thanks

discodrivercumbria · Nov 10, 2013

i would say your fuel pump may not be right! they make a noise but nothing like that! what sort is it? was it a cheapo?

thebiglad · Nov 10, 2013

Hugh said:
It starts much, much better now, but with a second or so of a noise like a cat being strangled when the ignition first goes on.

Good enough!

Thanks

I would say that is perfectly normal.

discodrivercumbria · Nov 10, 2013

thebiglad said:
I would say that is perfectly normal.

none of mine have ever done or sounded like that, a purr, but not strangulation!

thebiglad · Nov 10, 2013

discodrivercumbria said:
none of mine have ever done or sounded like that, a purr, but not strangulation!

One persons purr is another persons strangulated cat?

discodrivercumbria · Nov 10, 2013

ours must be gentle pussy's!

sierrafery · Nov 10, 2013

Hugh said:
It starts much, much better now, but with a second or so of a noise like a cat being strangled when the ignition first goes on.

Good enough!

Thanks

the filter's quality is important too...new branded filter might cure it

Hugh · Nov 23, 2013

sierrafery said:
the filter's quality is important too...new branded filter might cure it

...and it did too! A genuine LR filter (and air bleed valve) and it starts on the first turn of the key - even without pausing at the second position of the ignition switch. :clap2:

The pump still complains for a tiny amount of time, but it seems to be getting better (presumably as air works its way out).

Not sure if, as I discovered today, having two sealing washers on the water-sensor would have helped things but it only has one now.

Air in fuel system

Hugh

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thebiglad

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Hugh

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Hugh

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discodrivercumbria

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thebiglad

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discodrivercumbria

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