Ref:
dead aquastream - red LED blinks continously

I just got a new pump, and it exhibits the same behaviour; no difference with or without the deaeration jumper and pulsing every 1.6 second (instead of pumping continously). I can feel this pulse on the outgoing tube for the first 5-10 cm (high attenuation), but I can't feel it on the intake. I've gotten the air out of my system already, but the water doesn't come squirting out of the radiator vent (instead it flows slowly). The water coming out of the radiator with the open vent is forced by gravity - not the pump.

I do not believe the loop is obstructed. However tilting the reservoir so that the return-flow is above the waterline does not make any audible noise, and there are no ripples that I can see.
So either I'm doing something wrong, or I'm misinterpreting the pump.

* How should the pump look during normal operation?
* Should the red LED blink?
* Should the pump be pulsing once every 1.6 seconds?
* Would a complete obstruction somewhere after the pump cause this behaviour?
Problem solved. I switched to my intended powersupply (Corsair), and it started right away. The problem was that the AT-powersupply failed to provide sufficient startup-current.

Followup: Observation.
I placed a voltmeter on one of the other Molex-plugs, and noticed that everytime the pump pulses the voltage dropped to <5V (ie. probably close to 0V). I then connected 3 fans to the powersupply at the same time, and the effect is so pronounced that I can hear the fans die momentarily, then resume.
The powersupply is old; it's an AT-powersupply and as such does not need the jumper. I have successfully run 2+ harddrives on this supply without other load, as well as the three 120mm fans currently.
Should the startup-current be that strong?