Fuel Tank Issues

Morning Everyone.

I have been out shaking down the 90 after a full rebuild. The issue i have is that i have fitted a new vented non locking fuel cap to the tank and despite it being vented the tank bangs where it is holding a vacuum. Simple resolve was to remove the the vent valve assembly. The main issue seems to be that the tank is pressurizing! with no valve in i get a 6ft jet of diesel out of the filler cap when i go around corners and despite thinking i was out of fuel i could only get £16 of diesel in her. It would seem that something isn't right here, any ideas, fuel lines were only removed from the tank end. The tank has a sender in it with one fuel line attached and a seperate return to the tank. I am really stuck for ideas here.:doh:

MATT9711 said:

Morning Everyone.

I have been out shaking down the 90 after a full rebuild. The issue i have is that i have fitted a new vented non locking fuel cap to the tank and despite it being vented the tank bangs where it is holding a vacuum. Simple resolve was to remove the the vent valve assembly. The main issue seems to be that the tank is pressurizing! with no valve in i get a 6ft jet of diesel out of the filler cap when i go around corners and despite thinking i was out of fuel i could only get £16 of diesel in her. It would seem that something isn't right here, any ideas, fuel lines were only removed from the tank end. The tank has a sender in it with one fuel line attached and a seperate return to the tank. I am really stuck for ideas here.:doh:

Click to expand...

Only one of those statements can be true

Sounds like a faulty Diaphragm in the injector pump

Yeah i appreciate that both cant be the case but cant make sense of the fact that you can hear the tank banging as its sucked in and then splurts fuel if you take the valve out. Just hacked off that i want to get it to billing this year as i missed it by days last year and its not playing the game at the moment. I am sure its creating a vacuum as with the valve cap on it stalls and if you remove the cap it then eventually starts again, but cant make sense of the fact that it behaves like its run out of fuel, but clearly the tank must have fuel in it if i can only get £16 in it.

I had the same issue but without the fuel spilling out, the tank banged with air being drawn out then so much pressure built up air forced itself back in the tank, in the short term I drilled a small air hole in the filler cap washer and the banging stopped.

Replacing 2.5TD boost Diaphram - LR4x4 - The Land Rover Forum

After some searching i found this and it seems to be exactly what we are getting so i am gonna give this a try.

Right, job done, the old diaphragm had a two inch split in it and the rubber was very soft! So i can only assume from the condition that it has been like this for a while. I replaced the diaphragm which is as described "a bit fiddly" but we have no pressure in the fuel tank now, the turbo gives us the boost we never had and it pulls better in every gear. SO thats another job ticked off the list. However now the temp gauge is permanently on red hot (even before you start the car) so one down and just as many to go. Thanks for all your help and suggestions.

My "fuel tank issues" are that it lets the engine have too much fuel:doh:
:hysterically_laughi

With the tank pressurizing and reading this thread I intend to replace the boost diaphragm on our 90 TD (1989)

I hope the link with the images on how to do it is as easy as it looks.

Less than £20 from delphi for an original part.

Delphi Parts Store - Fuel Injection Pumps > Pump Repair Parts > Boost Components > Delphi Boost Diaphragm

Will report back.

Replacing 2.5TD boost Diaphram - Land Rover Technical Archive - LR4x4 - The Land Rover Forum

Well I followed the link and the job went 1st class.

The text is all useful.

The old diaphragm had full disintegrated.

Removing the bottom bolt 1st was tough to access and in the end I borrowed a very small 8mm socket with 6mm drive just did the job.
On the top the socket wouldn't fit but it was much easier and the 8mm spanner did the trick.

Runs a tad better now just to see if the tank pressurizers.

Took about 75/80 minutes but cleaned it all, sub 1 hr would be a fair estimate.