Sucking Air

1996 P38 2.5dse

The car runs fine until i get down to quarter of a tank then it seems to pull air through which sits in front of the fuel filter. Also makes the engine take about 30 seconds to start and will conk out when driving. Put in a scores worth of diesel and after a little while the problem goes away so i know its got to be tank related.

Now I read somewhere this is a perished line in the tank, Which seems plausible but it could also be the sender saying I've got more fuel than i actually have. So how do you test a sender and what is the inner and outer diameter of the fuel pipes in the tank.

Also how do i get to the sender is it under the rear seat or does the tank have to come out.

Thanks in advance.

tank has to be dropped check to see if pump is actually pumping first could be the pump that is not working aswell easy test pull pipe off to filter turn ign on and crank for a couple of seconds see if fuel comes out easy way to check sender wait for it to get to a quarter and fill it any more than 75 litres(90 litre tank) its reading wrong unlikely though, i replaced mine with 8mm fuel pipe (too tight to buy a new pump just for a bit of pipe)

ian24895 said:

tank has to be dropped check to see if pump is actually pumping first could be the pump that is not working aswell easy test pull pipe off to filter turn ign on and crank for a couple of seconds see if fuel comes out easy way to check sender wait for it to get to a quarter and fill it any more than 75 litres(90 litre tank) its reading wrong unlikely though, i replaced mine with 8mm fuel pipe (too tight to buy a new pump just for a bit of pipe)

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i know the pump is working as above that level it runs fine. was 8mm the inner or outer dimention of the pipe. same here though i dont see the point of spending £120 for £1.50 worh of pipe

8mm inner must be submersible fuel pipe my friend has a scrap yard so i could find one that matched closely enough dont know if normal rubber fuel hose will do the job and last as original is plastic

No, your in-tank pump isn't working. Above roughly 1/3rd full the engine fuel pump can suck fuel from the tank, below this level there isn't enough suction head, so you get poor and eventually non-existent starting/running.

New pump can be bought for £80, it's an arse to fit but the solution to your problems.

lanmjdun said:

No, your in-tank pump isn't working. Above roughly 1/3rd full the engine fuel pump can suck fuel from the tank, below this level there isn't enough suction head, so you get poor and eventually non-existent starting/running.

New pump can be bought for £80, it's an arse to fit but the solution to your problems.

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see you point. either way ive gotta take the tank off

It's a **** of a job alright, the first time is the worst, here're a few tips,

You can't siphon fuel out of tank easily so you'll probbaly have to drop it with 1/3 or 1/4 full, raise vehicle to full wading height, disconnect the filler hose from the tank, undo the nuts off the front, loosen the middle nut at the back, remove the two outer bolts at the back, lever off the tank cradle over the front studs and the tank should drop to the floor on top of your leg or arm, unless you have some blocks underneath it, leave the tank where it is and remove the pump from the top, its tricky to get the tank out from under the vehicle and there is no need to do so.

lanmjdun said:

It's a **** of a job alright, the first time is the worst, here're a few tips,

You can't siphon fuel out of tank easily so you'll probbaly have to drop it with 1/3 or 1/4 full, raise vehicle to full wading height, disconnect the filler hose from the tank, undo the nuts off the front, loosen the middle nut at the back, remove the two outer bolts at the back, lever off the tank cradle over the front studs and the tank should drop to the floor on top of your leg or arm, unless you have some blocks underneath it, leave the tank where it is and remove the pump from the top, its tricky to get the tank out from under the vehicle and there is no need to do so.

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lanmjdun you are a legend, Ill post on there in a week or so as to how i get on

Job Done.

Well one slight flaw is that i broke a bolt. But apart from that its all workin now.

I did manage to siphon out about 35 liters. i put one side of the car up on the kerb and the other on a pallet i stole from work. the hardest part was disconnecting the filler pipe needed one person to rock the tank while another jammed a pice of wood between the tank and pipe to leaver it off. also had to go out and get a 30mm julibee clip as the one on the back pipe of the pump seemed to be a funny one use only style clip. took the tank out from under the car as i had the extra ground clearence under the diff.

for anyone whos reading this with the same problem you will need these parts
1 pump
1 pump seal
2 oilves ( get a couple of spares just in case as there a one shot deal )
2 nuts
1 30mm julibee clip
1 big arse julibee clip ( at a guess 3 inch but check first)

tools you'll need

6mm socket
13mm socket
17mm deep socket
assorted extension bars ( i put three together for the back bolts)
approate rachets
thred lock
two 15mm spanners ( the nuts on the pump are 14mm but with the lack of space and the crud 15mm are easier to use)
soft brush (clean top of tank before removing pump)
jack (place under tank when kncking the cradle off)
torch
a pair of those clear glases from homebase
optional
chock the front wheels and rasie the back diff as high as possible
siphon out the diesel into jerry cans

hi there i cheked to see if my pump was working like you sed and no fuel coming out of pipe so i thort the pump was not working so i tuke tank of and pump out and testerd it with 12v and i can hear the pump runing and hall pips on the pump ar ok do you no if there is eny thing els i can cheqe

hi there car hall sorted it was a bloked fule pump

Hi all,
I,m from Macedonia.I had the problem with the back fuel pump.Solved by fitting a new one.But, I think that this small pump is the main problem in diesel RR.I ,ve had starting problems for a long time,4-5 years.The air bubbles noticed in the hose,but couldnt suspect on the pump.The starting was sometiomes OK,sometimes annoying.
Now I reccomend to all RR diesei owners to check that pump.Guarantee that they will be more happy after that.Rgds.

woodware said:

Hi all,
I,m from Macedonia.I had the problem with the back fuel pump.Solved by fitting a new one.But, I think that this small pump is the main problem in diesel RR.I ,ve had starting problems for a long time,4-5 years.The air bubbles noticed in the hose,but couldnt suspect on the pump.The starting was sometiomes OK,sometimes annoying.
Now I reccomend to all RR diesei owners to check that pump.Guarantee that they will be more happy after that.Rgds.

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Hello to Macedonia

woodware said:

Hi all,
I,m from Macedonia.I had the problem with the back fuel pump.Solved by fitting a new one.But, I think that this small pump is the main problem in diesel RR.I ,ve had starting problems for a long time,4-5 years.The air bubbles noticed in the hose,but couldnt suspect on the pump.The starting was sometiomes OK,sometimes annoying.
Now I reccomend to all RR diesei owners to check that pump.Guarantee that they will be more happy after that.Rgds.

Click to expand...

Hi and :welcome2:....good to see a "newbie" and with sound advise too....tis a common issue on oil burners!

Hi,
Thanks for welcome words.I saw a question how to test the pump.I took a plastic container,put 3-4 litres of diesel,put the whole assembly with the pump filter into the diesel and connected to a 12 v battery.If there is diesel coming on top,than You should be happy.
I posses an Land Rover SII ( 1969),too.But,this is another story.
Cheers.

Anyone know if this is true for petrol ones? My car has exactly the same symptoms, once low on fuel (guage indicating less than a quarter) it starts acting like its fuel starved, but fill the tank and its fine again. I think the sender is ok as matches more or less what I fill at the pump?

Hi,
After I changed the rear pump,the vehicle is like a new.Before the start problems were present,now the start is almost immediatelly.The annoying thing is that such cars should be OK for a long time and kilometers.But,these are not.