XUD7 starting issues

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xceirwenx
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Joined: 12 Jul 2021, 21:01

XUD7 starting issues

Post by xceirwenx »

Hi,

I'm having trouble with my XUD7t in my 309. Suddenly one day spluttered and cut out at 70mph then wouldn't then restart. Would turn over but no fire. Eventually one random day it started again, so took it to work to have a look. As it was starting and running ok just replaced fuel filter, filter housing, leak off pipes and looked for fuel/air leaks - all ok. Again, it eventually wouldn't start again. Just turning over and not firing. On original Lucas pump. When it runs, it runs fine. Any ideas of where to check next? Don't want to carry on throwing parts at it and wasting money. TIA

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white exec
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Re: XUD7 starting issues

Post by white exec »

Working glow plugs are pretty much essential on these engines for a cold start.
Worth checking?

Check also there's a reliable electrical supply to the fuel cut-off solenoid (on the fuel pump).
IGN switches can go intermittent on some of their contacts with age, so try wiggling it when running.

xceirwenx
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Joined: 12 Jul 2021, 21:01

Re: XUD7 starting issues

Post by xceirwenx »

Glow plugs all good, and stop solenoid changed recently just in case but working. Can't even to get it to fire anymore after it running perfect for months

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moizeau
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Re: XUD7 starting issues

Post by moizeau »

Crack an injector pipe 1/4 of a turn then crank to ensure fuel is getting through. Hook up a 12v bulb to the glow plug rail to ensure the plugs are getting power. If nothing else these tests will confirm or condemn.

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white exec
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Re: XUD7 starting issues

Post by white exec »

If fuel is reaching the injectors, and engine warm (or GPs working), then brisk cranking should start it.
After checking that fuel is reaching the injectors (by cracking the pipes at the injector), when you crank, try rapidly using the priming button (or bulb) at the same time.
If it still won't fire, but fuel is there, possible that pump timing has slipped, although unusual.