Td5 non start - air in fuel system

Hi,
I have 2000 td5 discovery which won't start (not getting fuel)
The pump is good (has been replaced with a known good unit) but it constantly just pushes air around the fuel system. Iv ruled out the air bleed valve as being the problem, the fpr has been replaced a year ago so I think I'm safe to rule that out...

I can't see any leaks anywhere in the system.
The air can be heard loudly in the fuel lines in the engine bay and around fuel filter housing.
Could the injector seals cause this? I'd assume it would at least start even if the seals were leaking?
Any suggestions welcome...

Search td5 fuel purge on here. I can’t remember sequence!

Thanks, I've tried the fuel purge several times, can hear air in the system the whole time it runs.
I can't get any diagnostics to communicate either.

Hi. That's not air you hear, it's the hissing of fuel as it passes through the FPR or filter, i can hear that too every time i turn ignition on or purge it while the engine starts fine... if the ECU doesnt communicate with diagnostics your problem is not with fuel but some management issue, can you communicate with other ECUs like ABS or BCU for example?

I know it’s always said but have you checked the ecu plug for contamination? You’ve done the fpr but did you do injector harness at same time? I used LR ones as the others aren’t the same quality. Nanocom might tell you the issue too

Thanks for the replies.
I'm certain it's air, you can hear it and see the return line from the cooler jumping around, but you could be right..
I have checked the ecu (all looks dry)
Harness has been replaced previously.
The crankshaft sensor has also been replaced.

I am using a hawkeye and it won't communicate with any ecu.I think it says preforming test and then just stays on that screen and not go any further.
I have a later 2004 td5 and it commicates ok with that.
I dont know if this is an option, would the ecu in my 2004 disco fit straight onto the other? I don't want to risk causing any damage so if there's the slightest chance of cauisng any damage I won't try this.

It could also be the fuel filter housing ??

matt101 said:

I am using a hawkeye and it won't communicate with any ecu.

Click to expand...

Then not even swapping the ECU would help cos you must program it otherwise it's immobilised, if it's with manual gearbox try to bump start it without cranking.

If no comms with any ECU there is a problem which can affect the starting too so concentrate on that cos the BCU acts as a gateway for diagnostics and any faulty ECU can disable the K line. First of all check battery voltage while cranking, if it drops below 10.5V it will not start.

you can put the non working ECU into the 2004 vehicle without damaging anything but dont try to crank it just connect hawkeye and see if there are any codes stored dont go into programming...if no comms with that ECU in the working vehicle you need a good one. Disconnect the battery negative lead before the swaps and then the original ECU will work like before. Good luck

Thanks,
Il have another look at it later and report back. Appreciate your help.