Thread: What happened to your D3/D4 today?

Originally Posted by matti4556

The ECM under the bonnet has an external factory "computer fan"!? OMG

fanny.jpg

I'd be surprised if it was needed except in the most extreme heat because with the amount of dirt and dust that gets down the back of the battery compartment over time I'd be surprised if many people had an operational one. might be better off removing the plastic shroud and fan entirely to allow for better passive airflow over the heatsink. it does throw a fault though (no red/yellow triangle though) with the fan unplugged.

Originally Posted by Bulletman

Attachment 175566

For those discussing the fuel flow, this is the diagram i have

And there it is. So I was wrong and I apologise to Discodicky for questioning that one. That's the EU4 schematic. With that fuel line configuration the restrictor prevents the majority of the supply flow going straight back to the tank. If the restrictor fails or is missing there will be almost no low pressure fuel pressure because the pump side of the filter will direct straight to the tank.

The schematic I have is from an EU3 with the 4 port filter, and the bleed orifice is built into the filter. Bad day when you don't learn something!
Now I need to find out why my return pressure is almost non-existent. I might be up for a new LPFP.

Originally Posted by BradC

And there it is. So I was wrong and I apologise to Discodicky for questioning that one. That's the EU4 schematic. With that fuel line configuration the restrictor prevents the majority of the supply flow going straight back to the tank. If the restrictor fails or is missing there will be almost no low pressure fuel pressure because the pump side of the filter will direct straight to the tank.

The schematic I have is from an EU3 with the 4 port filter, and the bleed orifice is built into the filter. Bad day when you don't learn something!
Now I need to find out why my return pressure is almost non-existent. I might be up for a new LPFP.

No sweat mate; partly my fault for not being more specific.
Turns out the 2 vehicles were both D3 circa 2008/9 and my mate says he had read something about this problem some time ago but could not recall where. He owns a D3.

So now I have the little bugger in my hot little hand and have measured it accurately.

"Plastic", with 3 tiny external ribs to presumably locate it.
Length 8mm
Dia 4mm except at one end it is 5mm because of a small "band" which is there I guess to allow location into the plastic 'housing' in which it locates.
At that 5mm dia end the hole dia is 2mm (I put a # 45 drill bit thru which is 0.081" which is near as dammit 2mm)
However, at the other end the hole dia is 1mm (a #58 drill bit which is .046" which is close enough to 1mm for the argument's sake)

The problem which occurred in both cases was that this little restrictor became loose in the plastic 'housing' in which it sits and this housing sits in the fuel return line just before entering the fuel tank. Therefore fuel was passing around this restrictor rather than going thru it.

One of the 'axioms' in the field of hydraulics is that if you increase the pressure, the flow decreases. Likewise, increase the flow and the pressure decreases. This is obviously a restrictor to decrease flow/increase pressure.

We all learn something every day.
The main thing as that if anyone with a D3 experiences low pressure probs then essential to check this!

Cheers,

Originally Posted by Discodicky

So now I have the little bugger in my hot little hand and have measured it accurately.

Any chance of a picture or two?

A failure of that device or its surroundings would cause low fuel pressure at the schrader valve. So one of the things to look for if you are diagnosing the low pressure fuel system.

Edit : Just to confuse further, here's a similar device in a completely different location : DISCO3.CO.UK - View topic - Robbie's Guide To The Low Pressure Fuel System
That's at the filter end of the tank return line.
normal_IMG_3479~0.jpeg

Originally Posted by BradC

Any chance of a picture or two?

A failure of that device or its surroundings would cause low fuel pressure at the schrader valve. So one of the things to look for if you are diagnosing the low pressure fuel system.

Edit : Just to confuse further, here's a similar device in a completely different location : DISCO3.CO.UK - View topic - Robbie's Guide To The Low Pressure Fuel System
That's at the filter end of the tank return line.
normal_IMG_3479~0.jpeg

I am too stupid to know how to put up a picture, BUT........ that little white crittur beside the valve in the persons fingers is THE item I've been describing!!!

Originally Posted by Discodicky

I am too stupid to know how to put up a picture, BUT........ that little white crittur beside the valve in the persons fingers is THE item I've been describing!!!

So in that description and teardown, that white orifice is in the filter end of the line where it "tees" between the filter and return line. Nowhere near the tank connection. To get to that one, you have to pull the molded nylon line off the end of the fitting.

It wouldn't surprise me to hear it's in different locations in vehicles of different years as they figured out how to make it work properly.

How completely and utterly "Landrover". Now to come up with a way of definitively testing it because to get to that one requires dismantling the line in a manner that might be "difficult to reliably reassemble".

For anyone who needs a laugh.. this is where I’m at this evening.

Front left strut sprang a sudden and fast leak today and I need the rig to get me to work in the morning sooo…

Be interesting to see what happens when that goo spreads throughout the system.