Infill very sparse, help!

Hello, I was looking for some answers as to why my prints have such sparse infill the image print had an infill set on 0.4 with a 0.35 layer height, When i change the layer height to 0.2 results are better but infill is still extremely sparse. Happens for both PLA and ABS. the second image is an example of another print with the same settings but the file comes out great and manages to do some infill not amazing but it works it just seems to be with bigger objects. My printer is a prusa i3 with a 0.35mm j head hot end using a bowden extruder.

slic3r gcode:
; generated by Slic3r 0.9.9 on 2014-08-22 at 14:23:10

; layer_height = 0.2
; perimeters = 3
; top_solid_layers = 3
; bottom_solid_layers = 3
; fill_density = 0.4
; perimeter_speed = 30
; infill_speed = 45
; travel_speed = 120
; nozzle_diameter = 0.35
; filament_diameter = 1.75
; extrusion_multiplier = 1
; perimeters extrusion width = 0.52mm
; infill extrusion width = 0.52mm
; solid infill extrusion width = 0.52mm
; top infill extrusion width = 0.52mm
; support material extrusion width = 0.52mm
; first layer extrusion width = 0.17mm

It looks like extrusion starvation. Some things to check:

Calibration of e-steps per mm.
Calibration of reference voltage for extruder stepper motor driver (might be missing steps).
Number of bends in the bowden tube - more than one increases filament friction and can cause extrusion starvation. Look at changing the path of the tube so there's only one bend / curve.

Speed looks OK.

Are you sure that your idler is tight enough on the extruder? This looks a lot like my first prints before I realized that the material was slipping.

I had similar problems. Solution was to make sure the filament is tight against the hobbed bolt and reduce extruder motor acceleration.