What is the problem with a TD5 when---

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Tim4x4

Tim4x4

Well-Known Member
Posts
2,207
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In the shed. Making engines for ME
What is the problem when a Defender 110 TD5 runs better with a full tank of fuel and runs poorly when the tank is about 1/4 full.
I thought my issues were fixed but having been running around for the last two weeks with the tank between 1/4 and 1/2 full I was happy with the performance it was giving.
Now today I filled the tank and instantly better performance, pulling off the forecourt I am thinking wow this is better. Why is this?.
 
Tim4x4 said:
What is the problem when a Defender 110 TD5 runs better with a full tank of fuel and runs poorly when the tank is about 1/4 full.
I thought my issues were fixed but having been running around for the last two weeks with the tank between 1/4 and 1/2 full I was happy with the performance it was giving.
Now today I filled the tank and instantly better performance, pulling off the forecourt I am thinking wow this is better. Why is this?.
Click to expand...
several things. pickup tube could have a pluged screen, or the pickup tube to the pump has a air leak. or fuel filter has restriction, or your fuel cap vent is plugged and a vacuum is created as fuel levels go down. Fuel cap replacement would be first choice, then the pickup screen
 
Thor1950 said:
several things. pickup tube could have a pluged screen, or the pickup tube to the pump has a air leak. or fuel filter has restriction, or your fuel cap vent is plugged and a vacuum is created as fuel levels go down. Fuel cap replacement would be first choice, then the pickup screen
Click to expand...
Thor1950 thank you for the reply-
The fuel filter is a new LR part at service 300 miles ago
The air bleed valve is new 100 miles ago LR part WJN500110
The none return valve VUB503950 not fitted to my vehicle
Is it through the cap that the tank vents then? I have been trying to find the vent as when I remove the cap it will draw in air.
The pickup tube you mention is it on the pump inside the tank or an external pipe?
And where is the pickup screen?
 
Tim4x4 said:
Thor1950 thank you for the reply-
The fuel filter is a new LR part at service 300 miles ago
The air bleed valve is new 100 miles ago LR part WJN500110
The none return valve VUB503950 not fitted to my vehicle
Is it through the cap that the tank vents then? I have been trying to find the vent as when I remove the cap it will draw in air.
The pickup tube you mention is it on the pump inside the tank or an external pipe?
And where is the pickup screen?
Click to expand...
last 2 are in the tank.
 
I used to run my td5 on hooky fuel from cans, it was white but dirty and the pump screen would block up at least once a year.
 
My TD5 fuel tank does not draw in air when l take off the filler cap.
That might be your fault, the tank is pressurizing and as it gets empty it will get worse.
 
lightning said:
My TD5 fuel tank does not draw in air when l take off the filler cap.
That might be your fault, the tank is pressurizing and as it gets empty it will get worse.
Click to expand...
lightning this is most probably my issue. when I unlock the cap it does draw in air.
The has written on it basic instructions which include the statement that a hissing sound will be heard when unlocking, I believed this cap to be the original LR part but now found out it is a replacement.
I have had the vehicle for 3 years and why have I not had this issue before? I do have the answer. Under the nearside rear wheel arch is a fuel tank vent that I have recently replaced.
This vent allows air out of the tank when filling. I still have the one I removed (I know sad) but it has shown me that the vent did not work correctly. It should be a one-way valve allowing air out only but air can freely pass in both directions so the old fill vent was also venting the tank when fuel level was dropping. Replacing the fill vent allowed the incorrect cap to become an issue.
Thanks Thor1950 and lightning good thinking.
I have replaced the filler cap.
 
Thor1950 said:
last 2 are in the tank.
Click to expand...

lynall said:
I used to run my td5 on hooky fuel from cans, it was white but dirty and the pump screen would block up at least once a year.
Click to expand...

lightning said:
My TD5 fuel tank does not draw in air when l take off the filler cap.
That might be your fault, the tank is pressurizing and as it gets empty it will get worse.
Click to expand...

Its not the filler cap.
I have replaced the filler cap with a new one which vents, taken it for a run started with a full tank no performance issues at all.
Country lanes, hills, fast roads and motorway it performed just as I would expect but when I had less than 1/2 a tank of fuel the performance started to fall off.
Gradually getting worse to 1/4 of a tank then remaining the same until low fuel light illuminated at which point I pulled in for fuel filled it up and instantly power restored.
Should I now be looking at the pickup pipe and the pickup pipe screen?
If so is it drop the tank or cut a hole in the floor its a 110 CSW TD5.
Also how urgent is this to get fixed? if I run it on a full tank and keep topping it up to full when it drops to 1/2 tank am I doing any damage?
 
You can get at the pick up pipe by cutting a hole in the floor. My Dad made it into an access hatch if he ever needs to get at it in future.

Shouldnt do any damage keeping the fuel topped up, it'll just annoy you haha

As an asside, I have noticed my 88" seems to run ever so slightly better with a full tank,not very noticeable, just seems slightly more responsive
 
Only you can decide whether it's worth cutting a hole in the floor or whether to lower the tank. There are a few items on Landyzone where people have done this and even provided measurements so you can get it in the right place first time. The pump is a cylindrical affair, which is spring loaded and secured in the tank with a thing like a large jam jar lid which has to be unscrewed. There is a mesh strainer at the bottom which can get obstructed by dirt. When I took mine apart for the first time it was covered in what appeared to be grass clippings.

The lowered performance could be a low fuel pressure problem. I had a new fuel pump about a year and a half ago and the car had a bit more pep afterwards - how far I could get up hills before changing down improved.
 
Brown said:
Only you can decide whether it's worth cutting a hole in the floor or whether to lower the tank. There are a few items on Landyzone where people have done this and even provided measurements so you can get it in the right place first time. The pump is a cylindrical affair, which is spring loaded and secured in the tank with a thing like a large jam jar lid which has to be unscrewed. There is a mesh strainer at the bottom which can get obstructed by dirt. When I took mine apart for the first time it was covered in what appeared to be grass clippings.

The lowered performance could be a low fuel pressure problem. I had a new fuel pump about a year and a half ago and the car had a bit more pep afterwards - how far I could get up hills before changing down improved.
Click to expand...

Finally managed to find the time to fit a new fuel pump that fixed it, now runs as sweet as a nut (what ever that means).
I decided to purchase a new pump before dropping the tank and extracting the fuel pump. Hoping to find crud in the tank blocking the pump as an obvious problem and a simple clean and Robert is your mothers brother.
No tank was very clean no sign of restrictions on the pump strainer so deduced it must have been delivering a low pressure.
Fitted new pump all back together and I am a happy bunny now :):):):)
 
I bought a fuel pressure gauge the other day because fuel pressure is such a key diagnostic issue with TD5s. Fortunately the fuel pressure was good and I was able to eliminate that as a possible fault.
 
Brown said:
I bought a fuel pressure gauge the other day because fuel pressure is such a key diagnostic issue with TD5s. Fortunately the fuel pressure was good and I was able to eliminate that as a possible fault.
Click to expand...
I believe I would have been better off using a gauge to test the fuel pressure in the first instance.
What gauge did you get?
 
Tim4x4 said:
I believe I would have been better off using a gauge to test the fuel pressure in the first instance.
What gauge did you get?
Click to expand...

Yes, I probably should have got one ages ago. How on earth did I manage without it? I'm at work just now and not near my gauge so can't remember what brand it is. It looked a bit like this
http://www.ebay.co.uk/itm/251963415237?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
I went for the one with the most bits of pipe and connectors in the kit I could find, in the hope of finding something that would fit. And fortunately some of them do! The bit that fits at the pressure regulator end is the L shaped thing with a blue bit on it at the top just under the handle. The push-fit clip-on bits fit the Land Rover's pipes exactly.

Incidentally, my repaired ECU came back last night and I was able to start the car. I permitted myself a brief period of rejoicing.
 
Brown said:
Yes, I probably should have got one ages ago. How on earth did I manage without it? I'm at work just now and not near my gauge so can't remember what brand it is. It looked a bit like this
http://www.ebay.co.uk/itm/251963415237?_trksid=p2057872.m2749.l2649&ssPageName=STRK:MEBIDX:IT
I went for the one with the most bits of pipe and connectors in the kit I could find, in the hope of finding something that would fit. And fortunately some of them do! The bit that fits at the pressure regulator end is the L shaped thing with a blue bit on it at the top just under the handle. The push-fit clip-on bits fit the Land Rover's pipes exactly.

Incidentally, my repaired ECU came back last night and I was able to start the car. I permitted myself a brief period of rejoicing.
Click to expand...

Thank you for that, it looks a comprehensive piece of kit and not just dedicated to the TD5 so very useful.
Indecently when you do a pressure test can you test the pressure before the regulator in the head so have reading of pump pressure and then test after the regulator?
 
I only tested the incoming pressure, because that told me I had more than 60psi which should be ample to start the engine. There's no reason why you couldn't fit it to the outgoing pipes too, but that wouldn't tell you very much - pressure would be low as the excess fuel drains back to the tank. If you clamp the outgoing pipe you can get readings well in excess of 60 psi. I've not had the regulator apart so don't know how it works, but I suspect it's a spring loaded valve that needs 60psi to open and let fuel back into the tank. So the incoming pipe and gallery in the head are kept at 60 psi as the fuel circulates.
 
Brown said:
I only tested the incoming pressure, because that told me I had more than 60psi which should be ample to start the engine. There's no reason why you couldn't fit it to the outgoing pipes too, but that wouldn't tell you very much - pressure would be low as the excess fuel drains back to the tank. If you clamp the outgoing pipe you can get readings well in excess of 60 psi. I've not had the regulator apart so don't know how it works, but I suspect it's a spring loaded valve that needs 60psi to open and let fuel back into the tank. So the incoming pipe and gallery in the head are kept at 60 psi as the fuel circulates.
Click to expand...

Good information Brown useful Thank you.
 
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