Fuel Tank

[Mark Y]

Anyone got any idea why my defender TD 90's fuel tank is pressurised, I opened the fuel cap and it nearly flew out of my hand there was so much pressure in the tank, :shock:

[trecfive]

Tank breather blocked.

[J.D.]

Yep the breather is blocked or is got trapped between something.

Got down an aquatic shop and get some airline and just replace the breather, lot easier than trying to unblock it.

[Mark Y]

Cheers for the advice, will have a go at the weekend.

[Les Henson]

This is quite common on the TD engines.
Breather blockage would cause suction, not pressure (fuel out to engine - no air in = vaccuum)
The boost diaphragm on the Injector pump splits on these engines - causing pressure to go back to the tank, which then causes the cap to blow off as you undo it. Take the boost pipe off after running the engine for a while with the cap on - if there's fuel in it, then the diaphragm is split. You can replace the diaphragm without removing the pump, and it's pretty straight forward to do, although the cover bolts are fiddly to get at.

[Mark Y]

Cheers, Another symptom I have is on start up the engine revs race and huge amounts of thick white smoke fills the drive, this clears after driving about a mile or so, though the engine sounds like it is gasping, I know it's done 93000 and is probably due changing for a 200tdi, but I would like to make it last as long as possible. :D

[Les Henson]

I think you'll find that the two problems are related. Fuel being pushed up the boost pipe will end-up in the compressor side of the turbo, which will eventually end-up in the engine via the inlet manifold - making it run rich. If your diaphragm is split, then replace it and run the engine for a while. You'll probably find that it will clean itself up after a while.


Les.

[90Mike]

Well that will give you something to do tomorrow mate give me a bell if you need a hand with anything  ;)

[Les Henson]

I should have added that there are two springs and a shim washer that you have to re-use - it's important that the height of the central pin on the new diaphragm is the same as the old with the shim washer fitted. The springs are different tensions too - one is a damping spring and the other is a control spring, so make sure they go back in the same position. You can adjust pin height with a stupidly small allen key and (I think), 8mm spanner.


Les.

[Mark Y]

Les, thanks for the advice, I have looked in the Haynes manual and there is no mention of how to do this etc, have you got any diagrams or a source I can get them from,thanks

[Les Henson]

You can get the diaphragm from any diesel specialist. You will need the serial number off the pump though.


Les.

[Les Henson]

I did one of these on Friday and remembered to take my camera :)
This is how to replace the boost diaphragm on a 2.5TD engine-

http://forums.lr4x4.com/index.php?showtopic=33384


Les.

[Mark Y]

Thanks Les, I haven't got round to doing it yet so this will be a real help, I had been looking on the net for diagrams or pictures. :D

[Mark Y]

Les, thanks for the advice absolutely spot on with diagnostic,  I have included picture of the diaphram or what was left of it, I am shocked it continued to go for so long.
Thanks for the photo's couldn't have done it without.
 :thumbup:

[Les Henson]

Glad to be of help.
That's the worst diaphragm I have ever seen!


Les.