In short - If you are unable to (the satisification of the Examiner or Inspector) complete all areas of the PTS you may not pass the exam. You may want to look at number 2 in the following reference.
JAFI
http://av-info.faa.gov/data/practicalteststandard/faa-s-8081-14a.pdf
page 9
Satisfactory Performance
Satisfactory performance to meet the requirements for certification is
based on the applicant’s ability to safely:
1. perform the TASKs specified in the AREAS OF OPERATION for
the certificate or rating sought within the approved standards;
2. demonstrate mastery of the aircraft with the successful outcome
of each TASK performed never seriously in doubt;
3. demonstrate satisfactory proficiency and competency within the
approved standards;
4. demonstrate sound judgment; and
5. demonstrate single-pilot competence if the aircraft is type
certificated for single-pilot operations.
JAFI
http://av-info.faa.gov/data/practicalteststandard/faa-s-8081-14a.pdf
page 9
Satisfactory Performance
Satisfactory performance to meet the requirements for certification is
based on the applicant’s ability to safely:
1. perform the TASKs specified in the AREAS OF OPERATION for
the certificate or rating sought within the approved standards;
2. demonstrate mastery of the aircraft with the successful outcome
of each TASK performed never seriously in doubt;
3. demonstrate satisfactory proficiency and competency within the
approved standards;
4. demonstrate sound judgment; and
5. demonstrate single-pilot competence if the aircraft is type
certificated for single-pilot operations.