diso 20 in defender fuel probs

hi all, i have just fittes a disco 20tdi into a defender and have now managed to get the thing running on tick over. the problem is that whent he peddle is pressed the revs rise then fall back to tick over no matter how far down the pedle is pressed. i have changed all of the fuel hoses for new ones and replaced the up lift pump and also the filter.

there is air in the pipe from the up lift pump to the filter. is this normal? i dont think that it is. also when the primer is used the fuel is pumped up the pipe but then falls back down, i thought that there was a non return valve in the system?

any help would be greatly recieved as i am now at my wits end. thanks

have you heard the new engine run properly before you fitted it ?

do the revs still drop when you use the arm on the FIP to increase the revs ?

how did you bleed the fuel system after installation ?

oh and welcome to LZ and all that other polite stuff

200tdis dont have a non return valve iirc. are you using the correct bosch fuel filter housing with it or the old cav one?
Check all your fuel lines and blow them out with an airline. change the fuel filter (if not already) and put some fresh clean diesel in a can and try that. I had a similar problem with mine however that was a knackered injection pump from poor fuel.

thanks for the quick reply, the engine is from a complete disco that i drove home without any problems. and yes the revs drop when using the arm on the fip. it is a bosch filter. but not sure what iirp means???

i bled the system by removing the screw on top of the filter and using the pump and also by turning the engine over. but no matter what i try i cant get fuel out of the top of it. and can still see air in the system.

one thing that i have thought of though, i still have the petrol pump in the tank although it is not connected. can i use this instead of the up lit pump or would it be too powerfull?

crack open the injectors and run it for a short time, this should get any air out of the system

if there's no improvement feed the lift pump directly from a can of diesel - you might find air is being drawn in from the lines to the tank - or crap in the lines etc

thanks for that, i will give it a go in the morning

spriggsy said:

thanks for the quick reply, the engine is from a complete disco that i drove home without any problems. and yes the revs drop when using the arm on the fip. it is a bosch filter. but not sure what iirp means???

i bled the system by removing the screw on top of the filter and using the pump and also by turning the engine over. but no matter what i try i cant get fuel out of the top of it. and can still see air in the system.

one thing that i have thought of though, i still have the petrol pump in the tank although it is not connected. can i use this instead of the up lit pump or would it be too powerfull?

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WOAH BUDDY!!!!

PETROL PUMP in the tank?
So this was a petrol defender now fitted with a Disco diesel engine?

It is drawing air somewhere.

You should continue to use the lift pump on the engine, and that MUST get a clean and free SUCK at the fuel in the tank. If you are drawing fuel through an in-tank pump there may be a resistance to the flow that is creating too much suck and drawing in air.

I suggest you revise the fuel system and make it true to the needs of the diesel,

CharlesY

hi all thanks for all the help recieved so far.

i have tried puting a tube straight from a jar into the uplift pump but with the same results. however if i use the petrol pump and connect it straight to the filter, therefore bypassing the uplift pump it works perfectly. seems that i have just brought a broken uplift pump???

anyway seeing as it runs fine on the electric pump do ypu think that this would be ok?

Yes but it might not provide enough fuel to cope with the engines demands at higher revs or when it generally needs more power. By all means fit a mechanical lift pump, preferably not a britpart (although I dont have any problems with mine). Ask for a Delphi, and fit that instead of the current lift pump. Then, keep the electric pump in the tank but DO NOT have it plumbed in. Use it purely as a backup should the mechanical lift pump fail.

spriggsy said:

hi all thanks for all the help recieved so far.

i have tried puting a tube straight from a jar into the uplift pump but with the same results. however if i use the petrol pump and connect it straight to the filter, therefore bypassing the uplift pump it works perfectly. seems that i have just brought a broken uplift pump???

anyway seeing as it runs fine on the electric pump do ypu think that this would be ok?

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The petrol pump should be OK for a while, but as diesel oil is so much thicker than petrol and thus MUCH harder to pump, don't expect the pump to last forever.

I think the fact remains that there is a problem in your fuel system that you would do well to fix sometime quite soon.

Nice that you now know the actual engine runs well.

CharlesY