Juki Foot Pedal
 

When I push down on the pedal to speed up the stitches, the fabric puckers with the stitches made. How can I resolve this?

It sounds more like a tension issue, or feed dogs. The foot controller is only responsible for your speed. Are your feed dogs fully up? Do you have the proper presser foot tension on? Stitch length normal? Those are the things I would check... and also if there is lint, thread, or anything else in the feed dog area that may be causing a problem.

I agree it's not a foot pedal issue. I'm thinking your tensions are too tight.

Ok, but wouldn't the tension be a problem during "normal" speed? I seem to only be having this issue at "high" or fast speeds. Would you recommend I lower the tension then?

I have noticed the same issue on mine, lowered the tension a bit and it helped... have also had to rethread from time to time when doing high speed sewing as the tension can get wonky unless I'm consistently sewing at high speeds, which I almost never do...

Is your thread catching on anything, such as a notch in the spool?

Check your foot pressure. The fabric can be pulled between stitches if there is not enough tension on the fabric. I often sew wide open with my Juki, and never notice a difference. However I prefer to sew with a smaller stitch than most.

However, just about everything is going to be exaggerated when you go high speed - it's a good way to make sure everything is adjusted correctly. I've seen many machines that appeared to be adjusted correctly - when sewing slowly on heavier fabric. Switch to fast on lighter weight fabric, and it was obviously not.

BTW - that is how a gather foot works, it is formed so there is no pressure on the fabric behind the needle, so when the fabric is fed, it allows the thread to pull tight and pucker up the fabric. You can adjust the tension and stitch length to affect the amount of pucker, but it's the lack of tension on the fabric that allows the pucker to form in the first place.