That motor is trying to start on full load, the motor could be trying to take up to ten times the running current on start up so if there is any type of overload protection on a 4 amp SMPS it will shut down. You need something like a super cap or a battery in the circuit to meet the initial demand, messing around with resistors and plain capacitors will just come to grief.
This motor starting problem is something I see frequently in my line of work, customer "why cant wont my welder/ compressor run on my generator, after all the generator is 5 KW and the welder/ compressor is only three and a half, the generator must be faulty" I then have to go into long explanations of motor startup current demand when all I want to do is shout at them I told you you needed a bigger unit than that and why are you coming to me to complain I told you that those cheap Chines pieces of crap are not up to the job which is why I wont sell them.