Disco 300tdi hesitation and poor mpg

Hi
My 1994 m reg 300tdi has an anoying hesitation on acceleration at around 2500 to 3000 rpm. once passed the 3000 mark its fine and its fine before 2500. it also revs up fine while standing and there is no excessive smoke.
I think the engine is the pre electonic injector version.

I have tried some Forte injector cleaner in both the tank and straight in the fuel filter but its the same. Air filter is new.
Also i'm only getting about 20-21 mpg from it.
I've had the car for 18 months and its always been the same.
Any ideas will be greatfully received

Andy

Ummm, not meaning to sound rude mate (sorry if i do) but if your regulary revving a 300tdi past 3000 revs during driving then 21mpg isn't a massive surprise.

Check for air in the fuel filter. While you're at it, check the lift pump is capable of priming the fuel filter (little lever on the side of it) - if it's not making any pressure when you pump the lever up and down then yer lift pump is probably shot.

Cheers,

Hi
Thanks for the prompt reply.
Is there a blead valve on the filter housing?
I'll check the lift pump.

Thanks Again

Andy

TheMunster said:

Ummm, not meaning to sound rude mate (sorry if i do) but if your regulary revving a 300tdi past 3000 revs during driving then 21mpg isn't a massive surprise.

Click to expand...

i don't normaly rev the knacker of it it was just for testing purposes.
however i don't think its not pulling quite as well as it should so reving up to 3000 on some hills before changing up is needed sometimes.
probebly all part of the sam problem??

Andy

av1adm said:

i don't normaly rev the knacker of it it was just for testing purposes.
however i don't think its not pulling quite as well as it should so reving up to 3000 on some hills before changing up is needed sometimes.
probebly all part of the sam problem??

Andy

Click to expand...

ah right sorry, i misunderstood.

try what Adz has reccomended (FYI you need to push the lift pump level to the engine block and back to pump, not up and down like some people seem to think, only the last inch or so of travel actually does the pumping), if you have air in your fuel system then might be worth while chekcing your pipes etc.

Fuel lift pump is a known fault with the 300 TDi's like the other chaps said, it overstrokes causing it to fail. New lift pump part no. ERR5057 and gasket ERR 7339

Riggaz

mine was running fine, but i had a new lift pump lying around so fitted it and the difference was incredible, loads more power and able to rev all the way to the limiter on the road.

Thanks guys
All realy helpfull
after fitting the lift pump do i need to bleed the injector pump etc or will it be ok to just turn it over untill it fires?
if so where is the injector pump blead.
Thanks Again
Andy

you need to bleed the air out at the filter bleed valve, just make sure that the lever on the pump is getting full travel (not on the camshaft lobe for pumping stroke) if it isn't just rotate the engine until it does.

The failed lift pump usually gives poor performance but not increased fuel consumption.When was the timing belt last done,and if your car has EGR fitted you may want to check that the valve is not stuck open.Boost pressure ought to be looked at too,if everything else is OK.

Timing belt was done about 40k ago so it's ready for one.
do all the 300tdis have an egr valve and if so where is it?
how can i check boost presure?
Thanks for all the replies so far

Andy

The EGR valve is fitted on the exhaust manifold, with a steel pipe running from the valve to half way down the top intercooler-inlet manifold pipe. To remove this you will need a new top intercooler hose and an EGR blanking plate, for example;

Landrover Discovery 300Tdi EGR Blanking Kit + Hose - eBay, Land Rover, Car Parts, Cars, Parts Vehicles (end time 25-Sep-07 17:06:14 BST)

To check the boost pressure you'll need a reasonably accurate pressure gauge capable to reading in excess of 1 bar (you should be looking for a figure between 0.75 and 1.05 bar if I remember correctly) and a metal T-piece. There is a full description of exactly how to check it in the Haynes manual.

edit : when you remove the EGR, have a look inside your inlet manifold, if its full of a marmitey like substance then you might want to think about removing the manifold and cleaning it with a degreaser (or petrol). also might wanna have a look at your intercooler, that might need a flush out.

Just ordered an EGR blanking plate ddin't realise I'd have to get a new hose too. Can it be done without a new hose as not seen it mentioned before?

teshu said:

Just ordered an EGR blanking plate ddin't realise I'd have to get a new hose too. Can it be done without a new hose as not seen it mentioned before?

Click to expand...

you can just pinch the steel pipe shut after you've removed the valve if you really want, but personally I got a new hose, needed replacing anyway.

hi just tried priming the lift pump and there was no pressure when i was pumping so i think i'll get a new one.
Could the egr valve be causing both the low mpg and the hesitation?
are there any know problems after the valve is removed ie not passing emisions at mot etc??
Andy

emissions for the mot test are normally fine on any 200/300tdi without the egr valve (normally better as they can blow out black smoke when fitted)

uummmmmm makes you wonder why they were ever fitted??

av1adm said:

uummmmmm makes you wonder why they were ever fitted??

Click to expand...

To meet north american emmision specs from what I've read but can't be sure.

When your priming the lift pump, are you pushing the lever towards the block? The lever will move freely for about 90° and won't actually pump anything, its only about the last 3/4 of an inch that do any pumping, you'll know its working cus you'll be able to feel the resistance.

Hi
yes pushing it down to the block. there is little or no resistance aftaer pumping for 20 ish times