Bath taps with shower connection

Help : I have a set of bath taps which has a shower connection pull up plunger thing to change between bath and shower. The pressure on the taps is ok but when I pull the plunger , the taps stop but the water pressure decreases so the shower head just trickles ( well maybe a little more than a trickle ). I have changed the shower head and lead that connects it but still low pressure...Any ideas or are they not very good anyway? The feeders also connect to another shower unit that is fine so i assume it is this lever plunger thingy...Any help welcome...Cheers

have you tried disconnecting the shower hose and seeing what rate the water comes out the top of the mixer when you do? if it comes out of there slowly then I think it's safe to say that the lever mechanism is at fault. I don't know if they can be replaced without replacing the whole mixer or not.

Yes, I disconnected it and it bubbles up about 5 inches, Do you think that is about right? Thanks for your help so far,

you don't tell us if it's gravity or mains pressure.

no it's not the mixer taps at fault, did you check on the instructions for what pressure is best suited for them taps

i would say your gravity fed and depending on your feed pipes your connections you may of restricted the flow.

alot of taps now are designed for mains pressure and don't work on gravity.