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[Marketstreeman]

It just Won’t start, wife went to do school run
It will turn over but not fire, went to when RAC pit easy start in?
RAC and mechanic can’t get there laptop to talk to ECU even tho there is power to it, we didn’t think there was at one point.
Mechanic has checked all fuses, relays etc, we took the fuse board out and the 2 green printed Circuit boards under drivers – it seem to have some corrosion on one of the top three plug connectors cleaned up with nail file and replaced no joy!

So is just one of those Annoying electrical gremlins!!!!!

Any one with any ideas I’d be out of the dog house

 

[Arctic2]

What engine is it? was it ok starting when cold ? or will it not start when hot only, if the later & it is a TD4 then possibly is the cam sensor,

 

[Marketstreeman]

It started every time hot cold, wet or dry, I thought cam sensor but why no Coms with ecu?
Td4 bmw engine 04 face lift

 

[GrumpyGel]

The fact diagnotsic kit can't talk to the engine's ECU indicates an electrical gremlin - but it not starting does not necessarily.

I'm not sure what you're saying about the easy start. Did the engine start? Did it start and die almost immediately or did it start and continue to run?

The main problems for TD4s not starting appear to be (as said) the cam sensor, fuel lift pump failed/failing, wiring to fuel pressure sensor corroded (at socket), O Rings failed in the high pressure pump solenoid or injectors.

 

[Marketstreeman]

Ok appreciate your time thx, the engine rubbing a form of life with easy start, but did not run.
Had issues with fuel pump in tank last year so mechanic fitted an electric pump, up by the battery so tank pump was doing less work, this and tank pump all come on and seem to go for start, RAC even hit tank to make sure pump was alive!
So I guess Fuel is getting to rail, ignition on, dash all lights up, to begin with the ECU relay was make a loud clicking, RAC swap out to check relay wasn’t faulty. He check all fuse, both under bonet and dash foot well.
So he was running out of test he could do as ecu not Coms with his laptop.
The mechanic took dash fuse board out, some water damage to one of the 3 block Connectors on the top of fuse box removed the two green printed circuit boards and filed pins clean reconnected no change!
I checked ecu had power to it, a mate found wiring dig, and we fig Out which pin was earth and live, at ignition as not constant live.
So happy to think it’s a sensor cam, crank or even fuel valve but haven’t necessarily got the time and money to chase electrical gremlins through all of these without more than it’s got to be one of them

 

[GrumpyGel]

I didn't think a 2004 TD4 had a pump in the tank, thought it only had 1 in the rear wheel arch.

 

[Marketstreeman]

Only going on what I’ve been told/lead to believe. RAC did hit tank with rubber hammer!

 

[tlo]

Had issues with fuel pump in tank last year so mechanic fitted an electric pump, up by the battery so tank pump was doing less work

As far as I am aware there is just the one in the rear wheel arch sounds like someone has by passed it, I think only the earlier freelanders had a fuel pump in the boot

 

[GrumpyGel]

As far as I am aware there is just the one in the rear wheel arch sounds like someone has by passed it, I think only the earlier freelanders had a fuel pump in the boot

I wouldn't think they've bypassed it - if there is a pump in the engine bay, they would probably have broken into the pipework there to "assist" a failing pump in the wheel arch. Probably means they didn't replace the filter next to the pump in the arch and its clogged up!

 

[Marketstreeman]

Yes the fuel line in the engine bay was cut into, to put this new inline pump in, the lack of fuel could be the issue but that doesn’t solve the no Coms to the ecu

 

[Nodge68]

Had issues with fuel pump in tank last year so mechanic fitted an electric pump

There isn't a pump in the tank of an O4 TD4. The low pressure pump is in front of the rear wheel arch, along with the filter and sedimenter.

So happy to think it’s a sensor cam, crank or even fuel valve

Have you checked the rail sensor for corrosion? That's a common cause if starting issues. Also the high pressure fuel pump regulator O rings split, also giving a non start.

 

[Nodge68]

Yes the fuel line in the engine bay was cut into, to put this new inline pump in

Sounds like a bodge to avoid sorting out the real issue.

The COMs problem could be as simple as a dirty or spread connection on the data port.

 

[GrumpyGel]

I believe the engine ECU is working - or else the car would be "imobilised". I may stand to be corrected or confirmed by those that actually know - but when you turn the ignition on, the car's immobiliser computer will "handshake" to the engine ECU and exchange codes that must match. If they don't, the engine ECU will not provide fuel and the imobiliser ECU will not let the starter motor turn.

So, as the engine is turning over, I believe your ECU is working. Similarly, the fuel pumps are powered from a relay controlled by the engine ECU - so as they appear to be running, that's another sign the ECU is functioning.

Its a shame you can't get a code reader to communicate to the ECU as that would possibly give error codes if the cam sensor is faulty and will provide fuel pressure readings.

If the lift pump is not providing sufficient pressure, the ECU will not enable the engine to function normally. If pressure drops whilst the engine is running it will go into "limp mode" which is reduced power/revs - essentially meaning it will only recoognise the first (say) 25% of the accelerator movement/demand. I'm not sure if it will enable any fuel injection if the pressure is to low on start up?

The same is true if there is insufficient pressure in the injector rail - this is picked up by the pressure sensor on the end of the rail. This may be due to the pump not providing enough pressure, usually because a small rubber O ring/seal has perished, or because the the pressure sensor wiring is not sending the reading to the ECU, usually because the wiring connector to it is corroded and there is an updated/improved wire/harness/loom available because this is a common issue.

I find it a bit perplexing that your "mechanic" would cut into the engine bay fuel lines and install another pump. If the fuel pump is failing, it would presumably be easier to just replace it! As he has done what he's done, you'd have to question the whole setup. If he's put a pump in, is it suitable for diesel? If he's used one that's designed for petrol, I would have thought it would struggle with the more viscous diesel fuel. I would definitely question whether he's even considered the fuel filter and whether its blocked.

In the "good old days" of mechanical pumps driven off the camshaft, the cam driving them would wear and the easiest way to fix it was to wire up an electric fuel pump and bypass/remove the mechanical one. There's a bit more to consider these days as there are sensors and controls to monitor them.

 

[Nodge68]

I find it a bit perplexing that your "mechanic" would cut into the engine bay fuel lines and install another pump. If the fuel pump is failing, it would presumably be easier to just replace it! As he has done what he's done, you'd have to question the whole setup. If he's put a pump in, is it suitable for diesel? If he's used one that's designed for petrol, I would have thought it would struggle with the more viscous diesel fuel. I would definitely question whether he's even considered the fuel filter and whether its blocked

The additional pump could potentially stop the engine running. There's a low pressure rail sensor that monitors the low pressure pump output. Now my way of thinking is, if the rear pump has failed and the new front pump is working. The low pressure measurement could well be below that needed for the engine ECU to initiate fuel injection.

With these modern common rail engines, you can't simply bolt in extra pumps, without it upsetting something else in the system.

Personally I'd replace the rear mounted pump and remove the bodged in second pump.

 

[Marketstreeman]

Hi guys, thx so much for the feed back, I’m glad to say (only because ima big tall chap and had to almost break my neck to get in the dame thing)
the boss (wife) decided to sell her beloved freelander, we got a good price as she wasn’t starting and to all 5 Windows need replacement motors, the rear lens was broken, the heater switch was broken so all in all it was time for it to go.............