Commuters travelling from south of Dalkey in Dublin will not be able to get the Dart on Saturday until a fault is fixed.
Iarnród Éireann said overhead lines had been damaged and services would run from Dalkey to Howth and Malahide only.
Stations affected include Killiney, Shankill, Bray and Greystones.
“Engineers working on it at present. Hopefully will not be too long,” a spokesperson said.
Iarnród Éireann said Dublin Bus would honour rail tickets for passengers that are affected.
In general, normal rail services had resumed on Saturday but a number were affected by flooding.
The Sligo line has been closed between Longford and Carrick on Shannon due to high water levels and bus transfers are available.
The Belfast to Connolly line is also experiencing delays and bus transfers are also in operation in Limerick, Ennis, Galway, Rosslare and Gorey due to flooding.
