Usual intermittent TD5 starting problem

I know there's a lot of info out there already on this so apologies for posting again but it seems there's a lot of reasons why td5 engines have intermittent starting problems so i'm wondering what's the best next stop in resolving mine.
I have a 10p 2001 TD5 Defender, i inherited it's intermittent starting problem - it'll generally fire up first time if i turn the key and wait (probably around 40-60 seconds) for the relay behind the bulkhead to click and the fuel pump to stop before turning it over. If i try to start just after the glow plug light goes out it'll start first turn 60% of the time, if not it usually starts second attempt and if not that definitely third so not a pressing issue but i would like to get it sorted.
Stuff done: I've recently done a full service, replacing fuel filter above the nearside rear wheel and replaced the non return valve in the housing with a genuine landrover one. I've also replaced the injector loom and seal as there was the usual leakage problem and occasional miss-fire on startup (resolved since). I just replaced the started motor too with a professionally reconditioned OEM unit as i was advised these are better than many of the aftermarket options and i have to say it does crank over a lot quicker. Voltage on the battery reads good and doesn't drop dramatically when turning over. I replaced the relay under the seat too.
Haven't got the tools to check the pressure at the bar but i'll check that next time i'm near my local landrover mechanic.
I don't mind spending money to get it running perfectly but i don't want to fork out for a new pump if there's other easier fixes i can try first.
Any idea's?

Apart from the pump possibly crank sensor/ connector?
Mine had a noisy pump I thought was on its way out but after a service and a blast whatever was the issue cleared itself, pump very quiet and now starts on the button every time. Don't know if it was bad fuel or sitting around for 6 months that caused it

Thanks Jim, i was thinking crank sensor was a likely culprit or possibly the fuel strainer. The pump is not making unsavory noises and runs great when its running so i'm reluctant to splash out for a new one before trying a few other things first. Might try borrow a nanocom and see if it tells me anything about the crank sensor.

Do the fuel pressure regulators cause issues and is it something worth changing out?

tdfyffe said:

Do the fuel pressure regulators cause issues and is it something worth changing out?

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I guess the diaphragm can get weak but normally just need replacing when they start to leak, bit awkward to get at
I would have though if it was that it would present as a problem generally not just at startup

Could it be an air leak somewhere? Did you say you'd replaced the bleed valve on the new filter assembly and did it have the membrane in it

i replaced the non return valve, didn't notice a membrane, i just took out the old valve and put in the new one. There was nothing in the hose nearest the chassis which i found confusing as there was another fitting supplied with the kit presumably for this but i believe this is normal for the 10p engine and the15p has some kind of fitting that goes in there too?

I'd be inclined to put my money on the crank sensor as it runs great when started so surely an air leak in the fuel supply would cause hiccups while driving too? i will get the pressure checked when i get down to my local land rover mechanic to pick up a cps though.

if you get a crank position sensor, try and get a well known branded one rather than the Britpart ones that go for under £20 in some cases. The latter can throw up errors even when fairly new in my experience.

thanks, i usually get advice from a well seasoned land rover mechanic as to what to go for / steer away from

Does the fuel pump whine for several minutes when you switch on the ignition?
Its pretty easy and cheap to make up a pressure tester which can be screwed into the temperature sensor opening on the FPR, this will tell you about the pump and the FPR.

I'd describe it as a low hum, it's definitely not whining as it would if you were purging the system. I'll look into making a pressure tester, seems like a sensible thing to have in the tool box anyway.

any recommendations for crank position sensor? should i splash out the 236 quid for a genuine land rover one or any cheaper ones as good?

also any idea where i can get the part number for the 10p cps? was chatting to my mechanic today, he said its not something he stocks but fork out for genuine OEM