HELOC vs Selling property

[Homa Teramu]

I have a SF property a property located in Silver Spring, MD. I purchased the property four years ago (04/2014) for $289,000 with FHA loan (house hacked for 3 years). In 02/2016 I refinanced the loan to 15 years @ 3.12500% rate and switched it to a conventional; avoid paying PMI and take advantage of the low interest rate for 15 years amortization ($2,285./month). Currently, the principal on the property is $253,915. It has been rented out since May 2017 after I purchased a townhouse in Olney, Md for my primary residence(Price $357K, 30 years and 4.75 rate).

The rental property brings about $2500/month which does not cash flow, but only covers the mortgage, tax, insurance and half of the utility. As of now, the property has equity that ranges from $100K to 130K (minimum 100K).

So, my plan for 2018 is to expand my rental portfolio down to Baltimore, Md since the market at Silver Spring, Md is becoming more for appreciation, but not for the cash flow. My question here is which way should I go :

1. HELOC: pull 80-90% of the equity and keep the current rental property as it is (there is no room to increase the rent amount) ?
2. Or sell the property: pocket the profit for the next income portfolio?
3. If either of them are not good options how can I expand my rental portfolio ?
4. What are the main things that I need to consider deciding between the two?

Note: the rental property is a 15 year mortgage