Thread: 10P to 16P Fuel Regulator?

Make sure the fuel line supply from the tank goes to the top of the regulator.

Has the engine been running in another vehicle previously or freshly built ?

ok so after on and off again troubleshooting the defender I finally sorted it all out. I thought I should record the results and findings here as its sometimes hard to find information on specific problems and their solutions when you're searching.

The regulator issue: ended up being a non-problem. TR Spares built the engine up based on my VIN, so although its a 16P block they fitted a 10P head so the plumbing would all be correct. No worries.

The crank sensor issue (which I mentioned in another thread): I damaged the sensor when I removed the engine because I missed the step of removing it (dumb). Once I put a new one in I was then getting appropriate numbers in the nanocom for engine speed when cranking it over. I tried fitting a spacer as that was apparently done by LR in some markets, but that just caused faults so I removed it. The wiring at the plug was damaged by age (cracked) so I found a plug the same which was unused (it was beside the brake MC and just didn't plug in anywhere) so I chopped that off and made a repair of the harness with that plug. Checked resistance at the ECU end and all was good again. This did not turn out to be the "big problem" though.

Fuel pump issue: I jury-rigged a fuel pressure gauge by plumbing into where the fuel temp sensor fits. I was only getting 1bar. I assumed this was a faulty pump so I replaced it. I remain mystified as to why this was happening though because at this point I had changed nothing in the fuel system other than fitting a new filter. As it stands the old pump was fine. The new pump did not fix the problem, still 1bar of fuel pressure. Then I replaced the regulator, this made no difference. In desperation I replaced the air-bleed valve in the filter housing ($78!) and again, no difference. At this point I was a couple of months down the track from fitting the engine and very, very frustrated about the whole thing. I should note I also checked every part of the electrical supply to the pump, including putting 13v directly on the pump, this made no difference.

The solution: in a final act of desperation I physically traced every fuel line from end-to-end. This isn't simple because on my car where the lines leave the chassis rail and move across to the tank they're in a "bundle of snakes" as a result of some weirdness that went on when I fitted the long range tank years ago. Back in 2019 I had the fuel pump replaced by a Melbourne LR specialist - at the time they told me "the colour codes on your fuel lines were wrong so we couldn't get the car to start. Eventually we worked it out and fixed the colours so they're correct now" - I took this to be fact. I was wrong. They hadn't actually changed the colours around on the lines (which is a simple thing to do) so when I re-plumbed the new pump I was fitting the lines incorrectly - the low pressure line was fitted where the high pressure line should be. I found this by having someone wiggle the lines while I looked in the top of the pump. I swapped the lines around (and fixed the goddamn colours) and voila! she started right up. It then ran like a dog and pumped black smoke everywhere and refused to run smooth. Another round of troubleshooting things like oil-in-harness (which it did have but I fixed it years ago), wastegate actuator (had already fixed this years ago, but confirmed it's still fine) and testing the injectors with the nanocom (all good). Finally I took a few jerry cans to the servo and topped the tank right up to full then ran the fuel pump by bridging out the relay - this did the trick. It's now running perfectly as a TD5 should.

So in the end I don't really know what was causing the low fuel pressure initially (before I replaced the pump). All I can think was maybe a combination of things including a not-quite-full tank (it was about 1/2) and a blocked air bleed valve might have been causing the fuel to be aerated at the pump intake? Anyway, eventually I got there. The moral to the story is do not believe mechanics who say they've done a thing, and use first-principles when you're troubleshooting. My brain kept telling me "it has to be fuel" and my brain was right.

Now I just need to pull the oil filter housings back off because there is a leak somewhere.... always something!

Cheers,

Adam