Xantia - lumpy running, smokes

[Jaf]

Hello.

Yesterday Fred starting stuttering lightly at tickover and upto 2,000 revs, no loss of power or smoke.

Today I changed the fuel filter, she started perfectly and ran smoothly for a minute or so, turned her off. When I started her again she is really lumpy/ clattery and whiteish smoke badly. Revs ok and when back to idle is smooth for a couple of seconds. At high revs there’s black smoke (normal smoke for her age).

Does this sound like air ingress? The primer bulb only takes 5 pumps and makes no difference to engine running.

(The fuel pump and leak off pipes are only a few months old).

Thanks!

[Jaf]

Confused.

Changed the fuel pipe from fuel primer to fuel filter, for clear pipe. No bubbles. Engine ran nicely for 2 mins, then went lumpy/ smokey.

Adjusted static fuel pump timing. Engine runs nicely, no smoke!

How can a fuel filter change affect the fuel pump timing?!? Was the fuel pump compensating for the dirty fuel filter somehow?!?

[admiral51]

Maybe when you changed the fuel pump ( original post ) it was set correct for the fuel flow at the time, change the filter and increase the flow pump is out of time ??
Anyway glad it is sorted another Xantia continues to pound the highways and byways

[Jaf]

Thanks. Yes that’s something I’ve pondered. Can’t remember if I changed the fuel filter when I replaced the fuel pump. It’s possible I didn’t as it wasn’t an old filter. Hmmm.