1998 Chevy S-10 Hard cold starting at 6 degrees or less

I have trouble starting when outside temp is 6 degrees or less. Have to pump accelerator up to 10-
12 times and it sometimes starts. Cranks fine, so not
a battery issue. About 32000 since last tune up. I usually have to wait till temp hits 12 or 13 degrees
before it will start. Had new fuel pump put in about
2 years ago but, it did not help. It also starts hard sometimes in warm weather after sitting 30 - 60
minutes. I then hold accelerator to floor and it starts
fine. Can anyone help?