U's efforts earn a point.
Colchester started the game two points outside a play-off place and Plymouth were still within a chance of battling for the top of league as Doncaster failed to win in their last fixture.
Colchester United gave it a real good go against a promoted for the second home game running - but had to make do with a draw once again on Saturday afternoon.
U's fans knew a home win was crucial, having drawn their last two games which has kept them from entering the top seven.
The first Colchester United chance of the game fell to Tarique Fosu who collected the ball just outside of the box, and dribbled inside before placing his shot just wide of the far post.
There was another clear chance for the U’s on 9 minutes, an early cross from Brennan Dickenson found Chris Porter, but the striker’s header was directed straight at Plymouth keeper Luke McCormick.
A brief pause in play as George Elokobi and Oscar Threlkeld clashed shins as the two battled for possession at the corner flag.
Play resumed and on 25 minutes, and Drey Wright’s strike from range took a deflection off Jakub Sokolik and the ball fell loose in the box, but McCormick managed to claim the ball just before an on-rushing Porter who was inches away from poking home.
The first Plymouth chance of the game came in the 32nd minute, Antoni Sarcevic was played in to the box but fired a shot wide of Sam Walker's net.
Ten minutes before the break, Dickenson ran 30 yards into the Colchester half and picked out Porter with an inch perfect cross, but the striker mistimed his jump and it rolled just wide of the post.
A minute later, Wright found Fosu free in the box, but as he looked up he was surrounded by Plymouth defenders who blocked the imminent shot.
Plymouth quickly cleared a Colchester corner and mounted a counter attack, the ball was switched out wide but Cameron James’ brilliantly timed tackle denied the winger a clear run on goal.
On the stroke of half-time, a short corner from Wright found Fosu on the edge of the box, who twisted and turned to lose his defender before firing a left footed shot just wide of the keepers far post.
First chance of the second half went to Plymouth, as Sarcevic set up a volley for himself from 20 yards out, but the weak shot was easily collected by Walker.
Seconds later, Wright found some space and had Colchester’s first shot of the second half, it was on target but not enough to worry McCormick.
Next, Wright found Fosu on the edge of the box, whose shot flew passed the face of the goal out for a goal kick.
A long goal-kick forward by Walker was then collected by Dickenson who was racing forward, the winger managed to get the ball down and produce a low cross in to the box, but it was cleared away for a corner by a Plymouth defender.
Two minutes after the hour mark, Fosu found space 20 yards out and shot high over the crossbar.
Moments later, a quickly taken short free-kick was whipped in by Brennan and it took a deflection before rolling across the goal-mouth, out for a corner.
A long-range shot from Drey Wright took another huge, but important deflection for Plymouth away from goal, Eastman’s header from the resulting corner was gratefully caught by the keeper.
With 18 minutes left on the clock, a rare chance for the visitors came but Elokobi was present with a diving header to clear the danger from a deep Plymouth cross that looked like it might find Slew at the far post.
Another chance for the away side, as Gary Sawyer whipped a cross in to the box and found Threlkeld at the back post who couldn’t keep his shot down.
A long range 25 yard shot from Graham Carey was fired inches wide of Walker's post and almost gave the visitors the lead in the 82nd minute.
Straight down the other end, and Wright drilled in a low cross in for Porter, who controlled with his right foot before spinning his defender and firing a left-footed shot just wide of the post.
With four minutes of additional time indicated, there was plenty of time for Colchester to snatch a deserved winner, but it wasn’t to be as the game was played out with each side having a chance to take all three points, but neither taking their opportunities.
The point for the U’s wasn’t the ideal situation, but they still have a chance of making the top seven.
They now sit three points outside of the play-off places and need to pick up wins in their final two games of the season, starting with the away trip to Leyton Orient next week Saturday.