Scudo Scudo losing power

[Rudder73]

Hi can I get some advise please ! I have a 2002 scudo d non turbo. Van will run but lose power management light flickers on and off then sometimes will hear a rattling noise from engine! Took to garage for diagnostic but came back no fault codes!! He did say it might be fuel pump but he also said he don't wanna do it as its a nightmare to do!! Any words of wisdom would be much appreciated ....