Fans coming on separately ?? and fuel purge???

[tim shap]

I have just noticed that the fan on right comes on first then 3 or 4 mins later the one on the left comes on?? Is this normal as I have never noticed this before in 4 years happy motoring with my Chim 500. I have checked the wiring and all seems to be in order I have also developed "clunks" from the fuel tank and when releasing the fuel filler cap there appears to be a large pressure differential which again has not in the past been significant. I have checked the purge cannister in forward offside wing and cant really tell if its ok. There is an open ended pipe which when closed with thumb for a while builds up pressure although not sure which way....must be inward ??? tried blowing down pipe but valve seems to be closed thinks.. any views out there... Great trip to Blackpool at the weekend and enjoyed listening to the 4.3BV Griffs

[mk1]

Perhaps the pressure differential maybe a low flowing (semi-blocked) fuel filter? Change it anyhow there cheap enough!

[RobM]

The fans are supposed to be staggered as the surge can blow a fuse if they both start together. Dunno if the interval is supposed to be that long though ?

[Marshy]

They come on together on mine too. But they do have a fuse each, rated at 40amps. Peter Beech's site talks about staggered fans being a modification rather than standard factory spec.

[jase]

The fans have one fuse each so it shouldn't make any difference to fuses if they come on together. The rating for the fuses used to be 25 amps, the factory then recommended an upgrade to 30 amps because they used to blow all the time. Just while we're on the subject Fernies fitted a neon in the steering column that lights when both fans come on. If a fan comes on and there's no light it means one of the fuses has blown. They also fitted a button to override the fan switch and turn them on permanently.