Fuel System Advice Needed Please

Sunray-I40 · Mar 12, 2018

I have a 1995 300 TDI defender 110. Up to a few months ago I was getting 30 MPG ‘daily driving’. Sadly, the vehicle failed the MOT on emissions grounds. To cure the emissions problem I had to replace the turbo ( a vain had seized), recondition fuel injectors (they were 20-25% out), and recondition the fuel pump. At the same time I also had the engine carbon cleaned.

After all this work, the increase in power was phenomenal and the emissions were virtually zero but this came at a cost — I now get 25 MPG daily driving (and I consciously keep my foot off the accelerator pedal!).

I would like to get back to the 30 MPG I had (even if it means sacrificing some power).

All advice welcome as I know naff all about fuel systems.

mojo247 · Mar 12, 2018

be interested to know how you ever achieved 30mpg if you had all those issues?!

Sunray-I40 · Mar 12, 2018

So would I! Things like silcone hosing, full width intercooler, religious tyre pressure checking, eliminating steering play, etc got me up from 17 when I bought it. the guy who did the fuel work thought the high mpg was a fluke and something to do with boost pins and low end burning and the seized vain position --but i didn't understand a word of it.

mojo247 · Mar 12, 2018

mines also a 1995 300tdi 110, with a low mileage engine, serviced regularly, etc. but I'm lucky to get 20-25 on my daily drive! around the town, i imagine it's a lot less!

if I regularly got an average of 25, i'd be delighted with that!

Marmaduke · Mar 12, 2018

My old 90 used to do 28-30 week in week out. How are you measuring your mpg?

tottot · Mar 12, 2018

Less preassure on the go pedal.

mojo247 · Mar 12, 2018

I'm always a bit skeptical when anyone says there old land rover will do X mpg. I guess it's very subjective and very difficult to scientifically measure unless each time you fill up, you empty the tank until you run out!

Trench Rat · Mar 12, 2018

mojo247 said:
I'm always a bit skeptical when anyone says there old land rover will do X mpg. I guess it's very subjective and very difficult to scientifically measure unless each time you fill up, you empty the tank until you run out!

I’m still trying to work out my series 2s fuel consumption. Some times it just ****es away and sometimes it seems to last forever.

Internet seems to suggest between 15-20mpg

lynall · Mar 12, 2018

Just drive it and dont worry about the mpg, diesels like to be worked sometimes bloody hard, pussy foot them around and you will get issues.
I doubt very much you had a seized vane as thesy are not independent the only thing that can really sieze up and not effect the old style engine is the wastegate itself and the only reason it seized up? is becasue it never worked hard enough to reach enough boost to activate the actuator.
So once its up to temperature give it a hard time every now and then.

ogb · Mar 12, 2018

mojo247 said:
I'm always a bit skeptical when anyone says there old land rover will do X mpg. I guess it's very subjective and very difficult to scientifically measure unless each time you fill up, you empty the tank until you run out!

Not necessary to run the tank dry, surely? How about:
1. fill it to the brim, drive X miles, fill to brim again and note how much it takes to do so, divide this amount into miles covered = litres per mile.
2. Multiply this figure by 5 and take off 10% of the answer = MPG.
This is as accurate as I think I can get, accepting that there'll be a little spillage to start with from the brim full tank - but not a huge amount if you drive carefully - and most odometers overread. Mine does so by 10%, measured with GPS, so I allow for this.
FWIW I get a shade over 6 miles/litre "motorway" driving with a roof rack and roof tent permanently fitted. This translates as a true figure of about 27.3mpg for a 1995 300Tdi 110, 153k miles, driven with a light foot. I have all the gas-saving mods listed above except the boost pin.

lynall · Mar 12, 2018

ogb said:
Not necessary to run the tank dry, surely? How about:
1. fill it to the brim, drive X miles, fill to brim again and note how much it takes to do so, divide this amount into miles covered = litres per mile.
2. Multiply this figure by 5 and take off 10% of the answer = MPG.
This is as accurate as I think I can get, accepting that there'll be a little spillage to start with from the brim full tank - but not a huge amount if you drive carefully - and most odometers overread. Mine does so by 10%, measured with GPS, so I allow for this.
FWIW I get a shade over 6 miles/litre "motorway" driving with a roof rack and roof tent permanently fitted. This translates as a true figure of about 27.3mpg for a 1995 300Tdi 110, 153k miles, driven with a light foot. I have all the gas-saving mods listed above except the boost pin.

Surely its miles divided by litres used to refill times by 4.55 it will be accurate? do this over a few tank fulls to get a sensible average.

I love when you ask people mpg and their reply is, when I stick in 20 quid it does X miles!

Marmaduke · Mar 12, 2018

Put 28 litres of sunflower oil in mine at Morrisons this afternoon, got some right funny looks from my fellow shoppers

frog hopper · Mar 13, 2018

I do get between 28 and 30 to the gallon from my 200 Tdi 90.
Tyres are 235/85/16 but Cooper stt pro, and near new so rolling radius is a bit bigger than I expected from this size of tyre. I have checked my speedo with my gps and make allowances for this. I have also fitted a disco transfer box (old one was shagged) and given a very modest tweak to the FIP, this does make for relaxed running at 55 mph. (near enough to the 90 kph limit)
I check my consumption against the recorded milage when I fill up and keep the receipt to check amount used and keep doing this for at least 3 fills then just use an on-line calculator.
Trouble is that I live in a very rural part of France so do not often get stuck in stationary/slow moving traffic, just drive to suit myself really, and not too much town driving either. Really not like doing the daily commute in the UK.

flat · Mar 13, 2018

25 sounds quite good, I have a tdi and get 25-28 mixed out of it.

deffo worth giving it beans now and again, get the turbo spooling properl and everything working hard.

4th flat out up a hill is a good way, or hard acceleration in 3rd/4th

It will also get engine temps up and burn off soot deposits etc that hamper performance/increase emissions.

TDi engines definitely like to be worked; they weren’t meant for pootling around

Sunray-I40 · Mar 13, 2018

Marmaduke said:
My old 90 used to do 28-30 week in week out. How are you measuring your mpg?

I always fill to the brim at the same village garage with the same pump and zero the trip and then convert litres to gallons. the pump gauge or my odometer could be out, but at least it would be consistently out!

Sunray-I40 · Mar 13, 2018

tottot said:
Less preassure on the go pedal.

lynall said:
Just drive it and dont worry about the mpg, diesels like to be worked sometimes bloody hard, pussy foot them around and you will get issues.
I doubt very much you had a seized vane as thesy are not independent the only thing that can really sieze up and not effect the old style engine is the wastegate itself and the only reason it seized up? is becasue it never worked hard enough to reach enough boost to activate the actuator.
So once its up to temperature give it a hard time every now and then.

I saw the old turbo, the vane had seized half open, it wouldn't budge and couldn't be freed up.

Sunray-I40 · Mar 13, 2018

tottot said:
Less preassure on the go pedal.

yup. the first few tanks of fuel suffered from enjoying the new-found power but I've eased back and am more 'sensible' now!

mojo247 · Mar 13, 2018

ogb said:
Not necessary to run the tank dry, surely? How about:
1. fill it to the brim, drive X miles, fill to brim again and note how much it takes to do so, divide this amount into miles covered = litres per mile.
2. Multiply this figure by 5 and take off 10% of the answer = MPG.
This is as accurate as I think I can get, accepting that there'll be a little spillage to start with from the brim full tank - but not a huge amount if you drive carefully - and most odometers overread. Mine does so by 10%, measured with GPS, so I allow for this.
FWIW I get a shade over 6 miles/litre "motorway" driving with a roof rack and roof tent permanently fitted. This translates as a true figure of about 27.3mpg for a 1995 300Tdi 110, 153k miles, driven with a light foot. I have all the gas-saving mods listed above except the boost pin.

good idea, although being a engineer, I would have to do that quite a few times (say 20) so that I could get an accurate(ish) average as driving "style" and conditions are likely to differ each time you do the "X" miles!

lynall · Mar 13, 2018

Sunray-I40 said:
I saw the old turbo, the vane had seized half open, it wouldn't budge and couldn't be freed up.

Thats not a vane thats the wastegate flap and its the shaft that operates the flap that will have siezed, like I said above from under use.

Vgt and Vnt turbos have moveable vanes that can and do sieze form carbon deposits, the vanes also take the place of the wastagate, some are worked by pressure or vacuum and others with electric motors, worth a google some interesting stuff out there on them.

Kwakerman · Mar 13, 2018

1996 90 300 A bit sad I know however a good average!

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