I've seen the same with my Suzuki DT200EFI.
The hose at home has enough pressure, and so does one at the yard where I keep the RIB. However the tap nearest to where the boat is parked just doesn't have enough pressure.
I panicked the first time, but wen I moved it to the other tap it was normal again. I just have to make sure I stop on the way in to fush the engine rather than do it after I'm parked up.
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