Selespeed pump fails when car is running for approx 20min
I know there are hundreds of threads on Selespeed problems and I have read many but struggling to find any with the exact problem I have.
The selespeed system runs perfectly when the car is cold for a period after starting the engine or without the engine on. The pump operates when the drivers door is opened and after a few gear changes. With it on alfadiag the pressure is at about 55 after the pump has run and drops to about 45 after a few changes and then the pump runs again back up to 55 ish.
The problem happens after the car has been running for about 20-30 minutes and everything is up to temperature. The pump just fails to kick in when the pressure drops to 45 and I get a few more gear changes until it drops into it's 30's and then there isn't enough pressure to do anything and it kicks it to neutral.
The car has no MOT or Tax at the moment so I can't drive it and all of this happens with the car sat in the driveway. I was hoping to fix up the car for it's MOT as it's in pretty good condition elsewhere and I didn't want to break it.
I've changed the pump relay (between engine and battery, under the air inlet hose). I've tried a new battery and checked the fluid level. The previous owner of the car had a lot of selespeed problems and changed the actuator and accumulator for a different fault but this was about a year and a half to 2 years ago, could this have gone again so soon? He then gave up as he had this problem develop and I bought the car for the Wheels, leather interior and bose system for my old 147. I don't want to spend a fortune on it though so would hate to buy parts and replace them and it not fix the problem.
I'm thinking either pump or accumulator but I just find it strange that it will only ever happen with the car hot after running for half hour. The system seems to run infinitely with the engine off. I can sit and change through the gears constantly and it operates perfectly.
Any advice to save the car before I give up and break it?