This wall infill problem (no replies)

I'm using Marlin and am getting pretty good results except when an object has thin walls. I don't get good infill . I'm printing with 90% infill and have 10 solid layers set. If there is a wide solid surface, the infill is fine.

I think it has something to do with acceleration. I don't think the extruder has time to get up to speed on short runs. I've tried all kinds of acceleration setting but can't seem to get it fixed.

Any ideas?