Can m50 run off m40 fuel pump?

[DtfwithE30s]

I have a 91 318is and I put an m50 vanos in it recently and after diagnosing it looks like I'm not getting enough fuel pressure, cylinders 1,2,3 aren't getting enough fuel but 4,5, and 6 are working properly, it's not my fuel injectors, I'm getting excellent spark, I just want to know if the 4 cylinder fuel pump can power the m50?

[DtfwithE30s]

Or do I have an old shitty pump

[DtfwithE30s]

M42 sorry

[mpowerful]

I have not personally used the 4cyl pump but i have considered it. I pulled some and they were pretty small compared to m20 or m5x pumps which are about the same size.

[JOMARO]

My 20 years old m40 one didnt work well with my m50 , although it was running good with my m42 swap

[justin_l_]

Check your fuel pressure

[Nick_S]

Yes mine has been just fine...well aside from the original one crapping out but that was likely from 20+ years and over 200K miles.

[Roysneon]

I've used the stock fuel pump in my car that came with an m40 factory for years with a 24v. No issues.