1995 525TDS E34 difficult to start when cold ?

Recently it became difficult to start when hot or cold on an upward facing hill - garage said it was the fuel pump on top of the tank, tested pressure
(low) and fitted a new genuine part - problem didn't re-occur for a week. Now it is suddenly difficult to start but only when "cold", when glow plug indicator light comes on. Hot starts or when car has been used in last hour or two are fine - cold and hot idle are fine as is higher revs. - Its just the starting.....
I wonder if it is possible the glow plugs are, intermittently, not being activated when they should be..... Is there some relay to handle the presumably significant current these will all be taking when heat is called for and where is it to check. Can I put a meter on the glowplugs to see if they are being fed volts ? I presume they wouldn't all have failed together and even if one or two were dud, presumably the engine would start, with "misfiring", initially ?
Or any other areas I should be looking ?
Thanks,
Nick
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They do fail. Measure the resistance with a DVM. And also check they are being fed with volts when required.
--
*Life is hard; then you nap

Dave Plowman snipped-for-privacy@davenoise.co.uk London SW
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Based on experience with other diesels I'd certainly suspect the glow plugs. One or two may have failed in the past and you probably didn't notice it. Now another one or two have failed so it's finding it hard to start.
There will be a relay and you could check the supply to the plugs but I'd pull them and check them by connecting to a battery (assuming they are 12v as all the ones I've ever used were) and checking which glow and which don't, remember they get hot so clamp them in a vice to do this!
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