Land Rover Repair: Disco I surging, sec intervals, jason randall

Question
Hi,
I have a 97 Disco and when engine is warm to hot, the engine seems to surge
on and off, almost like you are turning the fuel on and off in 3 sec intervals.
Can you direct me?
I have replaced the fuel pump, but still have problem.

Thanks, Jason Randall

Answer
The surge is probably caused by some kind of fuel trim issue.  I think you would see the problem if you connected a t4 or autologic test system and watched the live data stream when the engine acted up.  You'd be able to see what parameter was out of range.