4.4TDV8 HPFP

Hi Guy's, my 4.4TDV8 l322 has just been diagnosed as the high pressure fuel pump failure.

What I want to know is that what are the chances of it knackering the injectors in the process?

Also, if I decided to fit a new pump, how are they timed to the engine??


Many thanks in advance

Ash

There is a good chance of damage to the injectors. You should have them checked by a specialist to be sure. A lot of modern hpfp aren't timed but there are always exceptions.

Yes, the pump is 'timed' - but you can replace it without special tools, you should replace the bolts and the 'O' ring seal though. LR specify that the HP fuel lines should be renewed, personally, as long as they're not corroded, I wouldn't bother. If your replacement pump comes with the gear pulley attached, then just rotate it to match the position of the woodruff key exactly to the same position as the old pump and make sure it doesn't shift whilst fitting.

As above, depending on the defect with the old pump, there is a good chance the fuel injectors, pipes & rails could be contaminated. the pipes & rails can be flushed out but it'd be wise to have the injectors tested.

For reference, contaminated with what? Does the pump internals break down AMD swarf/chips entering lines and injectors?

Yep, if the bushings are failing, then the vanes start to contact the carefully machined casing and start putting 'sparkles' into the fuel. There's a relatively coarse gauze in the top of the injectors but if the 'sparkles' get into the Piezo or pass through to the tip, then the injector is scrap. The clearance of a 'good' pump is such that a molecule of diesel will not fit between the housing and the edge of the pump vane, so you can see how a collapsing pump bushing (bearings are too coarse and have too much {relative} movement in them, some pumps have Phosphor-Bronze bushings, some have PTFE) would allow bits of the vanes to scrape on the casting and deposit bits of itself in the pressurised fuel. Don't worry about any that has gone back to tank, the fuel filters are good enough to capture that. The primary cause of bushing failure is contaminated or incorrect fuel, as diesel is the lubricant for the bushing too - so you can see if the pump is run dry, how it would cause damage, this is also the reason modern diesels have a 'driver inducement' misfire at low fuel levels and a 'forced shutdown' before the tank is actually empty, to preserve the HPFP & injectors.

OK, I've realised I was mixing up terminology with 'vanes', the pump elements - there's either two or three per pump, driven by lobes on the pump rotor (see exploded view) do have metallic close-clearance machined pistons, but not 'vanes'. Everything else is correct, particularly about the bushings and the adverse effect of contaminated or incorrect fuel on them and the pistons.
The pump elements have guide pins that the pistons run up and down, these also have bushings (mostly PTFE), clearly, any wear or excess heat will cause the pistons to contact the bore, creating 'sparkles'.

The exploded view below is very similar to a 3.6 TDV8 HPFP in that it has three pump elements and therefore doesn't need timing, the 4.4 TDV8 has two pump elements at 90 degrees and has to be timed, actually, phased is a better description. Incorrect timing will increase the load on the timing gear and can cause poor running (lack of power, surging, etc.) dependent upon how far out the 'timing' is.

Apologies for any confusion or misleading comments - it wasn't intentional, I put it down to a very long conversation earlier in the day about sequential diesel injection pumps on a old transit!