TD5 defender fuel pressure test. Dropping dead

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ONE LIFE LIVE IT. D90

ONE LIFE LIVE IT. D90

Active Member
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953
Hi guys

I've done a fuel pressure test on my defender TD5 from the regulator sensor today. As soon as the pump kicks in, its reading a healthy 4 bar! But immediately after the pump turns off, it drops to absolutely nothing. Not just a steady decline, it drops like a sack of ****. I thought they were meant to hold pressure in the head???? Or am I totally mistaken.

Reason for testing is, still haven't found the slow starting and struggling to start cranking over before it fires. The regulator was rebuilt with a bosch unit and new o rings, could it be faulty?
Injector seals done twice.

Any ideas guys?
 
Last edited:
l had this issue with our 2005 TD5
Slow to start and fire up, but OK once running.
Eventually (after doing the injector seals, harness, fuel filter housing, and fitting a new battery) it turned out to be the STARTER MOTOR
Even though it turned the engine over fine, it was faulty and putting some sort of voltage spike or interference into the ECU

A new starter and it started instantly from then on.
l would never have considered the starter, as the engine turned over fine.
 
lightning said:
l had this issue with our 2005 TD5
Slow to start and fire up, but OK once running.
Eventually (after doing the injector seals, harness, fuel filter housing, and fitting a new battery) it turned out to be the STARTER MOTOR
Even though it turned the engine over fine, it was faulty and putting some sort of voltage spike or interference into the ECU

A new starter and it started instantly from then on.
l would never have considered the starter, as the engine turned over fine.
Click to expand...

Thanks mate. Had a new starter on mine too
 
This was part way through the MIL bleed programme with the gauge attached today. At each pause in the pump cycle, it dropped to nothing. Pump engages straight back to 4



I thought they were meant to hold 4 bar in the head and not drop
 
ONE LIFE LIVE IT. D90 said:
This was part way through the MIL bleed programme with the gauge attached today. At each pause in the pump cycle, it dropped to nothing. Pump engages straight back to 4



I thought they were meant to hold 4 bar in the head and not drop
Click to expand...

how? when you break into the system it leaks fuel out it doesnt spurt out
 
jamesmartin said:
how? when you break into the system it leaks fuel out it doesnt spurt out
Click to expand...

Very good point. I feel stupid now haha!
I spose I've been seeing it like the screenwash pump, where it has a non return valve fairly close to the pump so the water doesn't travel all the way back to the jet each time.

Thats what I thought happened in the head.

So it appears that test is all perfect then? Onto the next to find the fault. Thanks alot @jamesmartin as per!
 
If you've got a fault code reader like a Nanocom you can have a look a the engine revs while it's turning over on the starter Mine typically shows about 260 rpm or so. If you can see something like this it shows the ECU is getting a usable signal from the crank position sensor and the starter isn't interfering. Alternatively, if you can start the car by towing it or rolling it down a hill but it won't start on the starter it suggests the starter is interfering with the crank position sensor signal.

My fuel pump switches itself off a few seconds after having reached 60 psi and the pressure drops. Once the engine is started the fuel pressure is less important - the engine will even run if you unplug the fuel pump completely. It's been like that ever since I've had it and it's done over 140000 miles, so I think the designers knew what they were doing.
 
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