yes, I ran the pump backwards on a bench a couple times for just a few seconds or so while it was sucking (from the "wrong" side) on some diesel fuel. It immediately spewed ugly stuff out.
I am no expert , but was told that the pump was not binary in behaviour. So I just mentioned that.
The fuel pump relay too is not necessarily a yes or no relay. It can be intermittent because of temp changes. The solder points expand and shrink.
That is why it is good to either jump it or borrow a good relay for a test.