If your API limit has been exceeded for the day, Zoho CRM will not 
respond to the API calls for the rest of the day. You need to wait till 
the API limit is reset for the next day. API limits are reset everyday 
between 12 am and 3 am PST.
If the present API limit does not 
meet your business requirement, you can increase the API limit/day. To 
know more about the pricing details to increase the API call limits, 
please send an email to 
support@zohocrm.com.
To optimize your API usage, get a maximum of 
200 records with each request and insert, update or delete a maximum of 
100 records with each request.
Note: In all the Zoho CRM Editions, the 
getSearchRecords & 
getCVRecords methods have a standard limit of 250 API calls/day.