Disco 2 TD5 Fuel priming does not seem to work

This site contains affiliate links for which LandyZone may be compensated if you make a purchase.
mad85

mad85

Active Member
Posts
524
Location
Malta
Whenever I change the diesel filter or touch something related to fuel (injectors, fuel regulator etc), and then try to use the automatic diesel priming procedure, this does not seem to be working. The pump is sounding like it is working but the car will still not fire up. After many attempts and many battery boosters, the car usually fires on 3 or 4 cylinders and finally after a short drive is becomes smooth again.

I do have a genuine fuel pump that seems to be working fine during normal driving. The battery has also been recently replaced for a heavy duty battery

Any idea what could be causing this?
Mark
 
Can you just confirm that when you start the priming/bleeding procedure the MIL flashes, you can hear the pump working, that you are giving it a good 5 minutes or so to run through the cycle, and that if you can still hear air in the system when it is done that you are running it again until the air is gone?
If the bleed process is working properly and you have one, connect a diagnostic tool and check the injector balance when the engine is runnning; a healthy injector should be flickering around +/- 1%. Obviously check for fault codes at the same time.
If the injectors are fine, it may be useful to check the fuel pressure at the Fuel Pressure Regulator. You can attach a gauge by removing the sensor and with the ignition on you should see a stable pressure close to 4 bar. If not, it could be the pump or the regulator at fault.
 
Yes that is the procedure that i used and it sounds like it the procedure is working. Will check the injectors and the fuel pressure. Do you know if the icarsoft i930 is capable of checking the injectors as you described?

Pressure Regulator was changed before the last attempt so it should not be the problem.

thanks
Mark
 
Sorry no experience with the icarsoft product. However, at the very least it should give you access to the DTCs. Any sign of crank position or top switch issues?
 
four errors came up... literally no idea what they mean, but i did try to clear them and they showed back immediately after switching it off and on again:

manifold pressure circuit fault. logged high
Air flow circuit fault. logged high
Road Speed Missing. Logged
Can error fault. Currently Active
 
The first two possibly mean you have an aftermarket MAF fitted and it is giving crap readings. Not sure about the third, but someone more knowledgeable will be along in a minute.
The CAN bus error might be a clue. This relates to the Controller Area Network and the linkage from the engine ECU to the transmission ECU. A commmon reason is that oil has made its way from the injector harness past the O ring seal at the connector on the front LHS of the rocker cover and into the red plug of the ECU. This can give some very odd symptoms including injector faults. Open the cover for the jack, remove the ECU and check for oil contamination. If present clean it with a suitable solvent (I like brake cleaner as there is no residue) and soon thereafter replace the injector harness. This is fairly straightforward as only the rocker cover needs to come off.
 
yes i had a lot of oil on that red plug which is why i had changed the injector seals, and injector harness and obviously cleaned it up with a good solvent
 
mad85 said:
yes i had a lot of oil on that red plug which is why i had changed the injector seals, and injector harness and obviously cleaned it up with a good solvent
Click to expand...
Apologies if teaching you to suck eggs.
How long ago did you change the harness and have you checked for oil again since? There will still have been oil in the line from the harness to the ECU which will have deposited more oil after the harness change.
 
Si Click said:
Apologies if teaching you to suck eggs.
How long ago did you change the harness and have you checked for oil again since? There will still have been oil in the line from the harness to the ECU which will have deposited more oil after the harness change.
Click to expand...
no problem... i cleaned it up about 3 weeks ago, so it wont harm checking it again.... since it is working decently I will not open the ecu though since i am going overland next week and do not want to risk anything... afterward ecu is coming apart and will let you know... map sensor should be siemens right?
 
mad85 said:
it is a manual. i used the icarsoft i930
Click to expand...
You can't rely on that scanner when it comes to the Td5 engine data... those fault codes are most probably false and the evidence is that manuals dont have CAN at all.. the Icarsoft is with OBD2 protocol which is not compatible with Td5
mad85 said:
map sensor should be siemens right?
Click to expand...
no, it should be genuine LR made by Bosch(MHK100640), it's too important for the management to play the lottery with aftermarkets... though you should read the codes with a compatible tester cos that manifold pressure code might not be real
 
Last edited:
well, now i changed the injector seals, fuel regulator, tank pump, fuel filter, map sensor and cleaned wiring loom to ecu. is there anyway to retest the priming function to see if this is now working as required? If it does not work I will try to change the return valve...
 
The only thing not done is a proper diagnosis with a compatible (ie non-OBDII) reader. The fact that your iCarsoft has thrown up a CAN bus fault demonstrates that it is not reading correctly as the manual D2 has no CAN bus to fail. If you can find someone with a Nanocom or Hawkeye it could save you a great deal of time and money. For instance a comparison of injector performance would be useful in order to rule out a fault there.
 
mad85 said:
well, now i changed the injector seals, fuel regulator, tank pump, fuel filter, map sensor and cleaned wiring loom to ecu. is there anyway to retest the priming function to see if this is now working as required? If it does not work I will try to change the return valve...
Click to expand...
You have to hear a hissing sound from the FPR area if the purge is performing well
 
tomorrow it is booked for something else (key fob/alarm trouble), i will ask them if they can check injector performance as well.

thanks a lot
Mark
 
You must log in or register to reply here.

Similar threads

mad85
Disco 2 TD5 Low Fuel pressure!!
2
Replies
22
Views
960
mad85
mad85
Skyisthelimit
Disco 1 1991 v8 fuel pump electrical wiring
2
Replies
31
Views
2K
Skyisthelimit
Skyisthelimit
Chazb5046
Disco 2 TD5 injector seal - disconnect fuel lines?
Replies
12
Views
1K
tilly2
T
F
Disco 3 (LR3) Dreaded Limp Mode - Suggestions?
Replies
13
Views
1K
ffisher
F
stumpyj
(2000 TD5 90 defender)TD5 Fuel Pump
Replies
7
Views
563
Anaconda
A
Back
Top