engine cutting out problem

[opusnine]

where to start.....
when driving you can drive for 2 hrs towing (a caravan) , car runs ok
any longer i.e 3 hrs and car develops a fault which it seems like the engine cuts out intermitantly then cuts back in... i.e car shudders
i have been told that it could be the fuel pump relay being faulty.... this would produce this effect. going to change this first.
it seems to me to only do this when the engine gets hot, as when towing. on A roads or running around town the car is perfect...
no engine management light comes on, the car just judders every so often, and then seems to rectify itself.
today was pretty bad, thought we were going to break down comming home from hol... but the car went ok again....
it is deffinatley an intermittant fault and as i have discovered these are very hard to track down...
before i go any further i was wondering if anyone had the same problem...
it is a L reg car and is a pleasure to drive apart from this annoying problem.
we are going to cornwall later this year and i dont want this problem to cause us breakdown on such a long run advice please

[Big Rod]

Sounds very much like fuel starvation.

Have you changes the filter recently?

[opusnine]

fuel filter changed 12 months ago,

been told it could be the fuel pump relay or something called an amplifier which is attached to the coil or dizzy its a small bakolite bit with 2 wires

anybody heard of this

[chrismec]

Deffo first things first, change temp sensor[back of thermostat housing above alternater] will do wonders.
Fuel pump relay symptoms, won't start hot when left for little while, can't say i've heard of relay doing anything else.
Oh and welcome to the foram

[king nero]

might be the dizzy, leads or spark plugs?
mine did, but it didn't wait for 2 hours...

[bstardchild]

Definately change the Fuel pump relay first - they are right little sods for getting hot and then chattering on the contacts causing some really weird symptoms - sometimes totally unrelated to fueling

"Low Battery Voltage" is a classic trouble code thrown up on a 24V when the relay is past it's best!!!