TD5 Fuel Pressure problem

Hi - currently have to wait for the air to be purged from the fuel system every morning and if the car is left standing for any longer than about and hour. Have replaced the pump, filter (only one O ring in the middle) and the regulator. The car sits on a clean surface and there are no signs of a leak anywhere.
Anybody any ideas what is happening, car runs fine when started.
Thanks

chrimcne said:

Hi - currently have to wait for the air to be purged from the fuel system every morning and if the car is left standing for any longer than about and hour. Have replaced the pump, filter (only one O ring in the middle) and the regulator. The car sits on a clean surface and there are no signs of a leak anywhere.
Anybody any ideas what is happening, car runs fine when started.
Thanks

Click to expand...

First thought



You have an air leak somewhere



Second thought



Are ya sure it's purging air?

It will be injector o-ring or the non return valve on the fuel filer housing. Try the housing non return first back left pipe about 6 quid if i remember other wise its the rings, not a too difficult job just time consuming.

Thanks for the replies - will try the non return valve first. Are the injector seals something a home mechanic can do, looks like some special tools are required according to 'Rave' ?
Regards

If the engine oil level is not going up,it will be the injector lower copper washers leaking,NOT the upper o rings.BOTH should be changed tho.

chrimcne said:

Thanks for the replies - will try the non return valve first. Are the injector seals something a home mechanic can do, looks like some special tools are required according to 'Rave' ?
Regards

Click to expand...

I did mine at home and you do not needing anything to special for the tool that goes in the cam shaft a screw drive does that but you do need a sling hammer to get eh injectors out square which is important.

Just be surgically clean, the injectors and the new rings and washers and the seats have to be spotless, use some meths and you will need a pair of long nose players and those stick things used for cleaning your ears.

Also check the rings you get from land did mine once without checking did 20 miles and broke down when i took it a part found a small nick in the side of one of the rings went ape at landrover parts guy got a full refund and all the parts again for free.

Good luck, take your time and most of all be clean.

Thanks fo the help - what is a sling hammer when it is at home ?
Regards

The fuel system is a pressurised one then if any leaks develop diesel comes out -- air does not get in.

Air is mostly likely combustion gas leaking through the copper washers at the base of the fuel injectors. Copper washers isolate cylinder bores from the fuel rail. Injector o-rings isolate the fuel rail from the cylinder head.

The non return valve (not always included) sits inside the rear left connector in the fuel filter housing, it is there to prevent the system from 'deflating' if the fuel pump is 'idled'.

The air bleed valve goes inside the front left connector. If the membrane is removed fuel will return to the pump via the air bleed line (path of least resistance) and the siphon function won't work properly causing potential suction problems when fuel level in tank is low. If the air bleed valve is plugged off then the system will loose its ability to self purge as air will go back to the pump through the LP return line and get picked by the HP stage suction.

Thanks for all the feedback - will try the air bleed valve first (easiest?) and post back but it could be a while. Interestingly I only seem to have the problem if the tank is less than half full.
Regards

Hi I have the same problem with my td5 discovery. I'm new to forums and was wondering if anyone can shed any light on it?!?! I have bought a new air bleed valve and non return valve for the fuel filter housing. The problem being, the non return valve I have taken out of mine has a piece of rubber hose on the end which is formed so it fits over the plastic non return valve at one end and the other end is pressed flat (this seems to make it a non return valve but without this the new plastic non return valve has nothing one way about it) This piece of rubber hose on mine seems to be at fault because the flat end doesn't seem to close fully. I've been back into landrover and they cant get the rubber part. Can anyone tell me how the non return valve can function without the rubber bit.

Just leave it out. It is only there to keep the system primed. Have only seen it installed in a few Td5s.

Ok thanks so I can rule out the non return valve then. I've replaced the fuel pump, fuel pressure regulator, fuel filter and injector seals. Do you have any other ideas? maybe I need to take the injectors out and get them checked??

if eny body has problems with air in the system looking at the diagram with the air bleed and the return of the fuel from engine i have blocked off the filter with bungs coupled up the return and the pipe back towards the the diesel pump so one knows if he as got air coming back from the engine ,and one can diagnose if the diesel pump is sucking up air or the engine is compressing air in the fuel lines ,hope this helps

My pump noise started after a service from a main dealer. Changed pump, changed air bleed kit, white pipe bleed filter "7" in the above diagram. No one way return valve in any pipe. Ps one way valve purchased and it is a plastic pipe, not one way at all. After three break downs, recovered by two major breakdown services and a subcontractor, we have found that air was leaking in through the top of the fuel filter. Looks like the garage has damaged or bent the thread of the fuel filter housing. Ps two filters have been fitted to try the said above problem. After a bit of manhandling it seams to have cured the cavitation of the fuel tank pump. Thanks dad! At least some one has earned their engineer title.

Thanks for the diagrams on here btw. Most helpful, better than some of the well known workshop manuals and the dealers/specialists I have talked to.

Clifton7 said:

My pump noise started after a service from a main dealer. Changed pump, changed air bleed kit, white pipe bleed filter "7" in the above diagram. No one way return valve in any pipe. Ps one way valve purchased and it is a plastic pipe, not one way at all. After three break downs, recovered by two major breakdown services and a subcontractor, we have found that air was leaking in through the top of the fuel filter. Looks like the garage has damaged or bent the thread of the fuel filter housing. Ps two filters have been fitted to try the said above problem. After a bit of manhandling it seams to have cured the cavitation of the fuel tank pump. Thanks dad! At least some one has earned their engineer title.

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Hi, Galen and I are both having the same problems - poor starting when the fuel level is low (half a tank in my case) and the car has been sitting for a while. Once mine is running she's as sweet as you like, runs great.

It's just the START-UP problem, and it is air in the system because EVENTUALLY it can be started using the PURGE and PRIME process, but it's hard on the starter motor.

So it seems to me that MTurri and you are on the ball here.

What exactly do you mean by "air was leaking in through the top of the fuel filter" ?

Was this a filter fault or the filter head, or O-Rings, or what?

What is the procedure we need to do to sort this and what bits do we need?

I am pretty sure my injector washers are OK. They were VERY carefully done not so long ago.

darker said:

if eny body has problems with air in the system looking at the diagram with the air bleed and the return of the fuel from engine i have blocked off the filter with bungs coupled up the return and the pipe back towards the the diesel pump so one knows if he as got air coming back from the engine ,and one can diagnose if the diesel pump is sucking up air or the engine is compressing air in the fuel lines ,hope this helps

Click to expand...

Hi,

It is not clear what you have done.
Can you make a diagram of your alterations?
Did it work for you?

There is a test to be made to isolate this kind of problem(unless it's a management issue.... and u'll need a teser for that) .
I'll quote a really knowledgeable guy from an other forum named Ricky who teached me that, cos i might mix it up with my english, (and pay great attention to all the aspects cos it's important):

"If you attach any design of gauge, screw in(in the FPR instead of the FT sesor m.n.) or inline, the pressure will rise to 4 bar when you put the ignition on and then drop when you switch off, i have seen quite a few defective pumps that produce 4 bar and you think great pumps fine but then it drops significantly on cranking and wont start.
A common test i also do is attach the gauge (again either sort), ignition on then clamp the fuel return pipe, note the pressure which will normaly be above 4 bar, clamp the fuel feed pipe and ignition off. What you have effectivly done is pressurised the system incl the head between the two clamps. If its all sound ther pressure will hold, if it drops you have a leak, could be FPR, injector seals or anything else inbetween. by moving the return clamp you can rule some things out eg fuel cooler.
The longest i have ever tested for is whilst i have a cuppa, any drops normaly show by then.
If you dont have a gauge to test the pressure and its a none starter, clamp the return pipe as it increases the pressure, i have had a couple of none starters that start when clamped indicating a failed pump."

I think this test will be quite relevant

Hi all
Had the same problem with my 54 reg TD5 Disco with 140000 mls. It started with difficulty in starting if the Disco had been standing for more than hour. After much testing it turned out to be 1 (only 1) of the copper washers on the injector not seating properly. If you looked carefully at the washer you coud see a fan shape which is where the pressure had been escaping. Recut seats & replaced all washers and seals, straight away felt like a new car has now notched up 159000 mls & no problems.
Happy new year.

I hear all these experiences, but I still wonder why my TD5 is fine when the tank is well filled, and gets progressively worse as the fuel level goes down.

Ideas?