When I flush my toilet bowl the flap doesnt stay open long enough for a complete flush.

You're to replace shutting valve.

Remove and clean the flush valve and the flush valve seat(it is the flap that opens up to allow water to flush the toilet). Once the edges of the valve and the seat are cleaned, possibly with "0000" grit bulldog steel wool, it should not leak anymore. To make sure it is not leaking, once tank has refilled completely, put some food die in the tank. If, after 10-15 minutes, the water in the toilet bowl is colored, you have a leak from the flush valve. Replacing the flush valve is very easy - just bring the old one with you to the hardware/plumbing store and ask for a replacement. Blessings and good luck!!

Check the water level in the tank and also make sure the flapper is staying in the up position long enough for a complete flush.

Sounds like you have a clogged drainline or vent-stack. Fill a large bucket with about three gallons of water and dump it quickly into the bowl. If the drainline/vent is clear, the toilet will "flush" like a gravity toilet and the water will drain from the bowl almost as fast as you can pour it in.

If the water level in the bowl slowly rises (as if it's about to overflow) and then slowly drains, you have a clog somewhere.

All toilets, regardless of their flushing mechanism, require a clear, unoibstructed drain/waste/vent system to extract waste.

If the toilet "flushes" with the bucket of water, you may want to call Flushmate tech support (the number is on top of the tank) or check out the installation and troubleshooting videos at howto.flushmate.com.

Hope this helps.

Alot of times this problem occurs when there is not enough water in the tank behind the seat and bowl. Lift off the tank lid and see how much water is it, It should be near full.If it is not your problem is not enough water.

The siphon mechanism works on a vacuum principle. If there is the slightest damage to the siphon membrane you will experience the problem you describe. A new siphon is required.

flush time depends on how much water is in it,
the water level flote has an adjuster on it, but i cant rember were it is,,, sorry

check water level in tank if low adjust float to proper level inside tank will see a level line also check flap as to opening all the way may have to adjust chain if problem continues hard water can cause build up in water holes and narrow tank to bowl tube

hello, this is a standard toilet you will need to inspect the flapper that is the rubber flap that holds the water up in the tank it works when you pull the lever it pulls the chain upward and lets the water flow if this flapper is old it may not stay up long enough for the water to flow. open the tank top and flush the toilet see if this flapper is staying up long enough and giving the tank enough time to empty if not change this rubber flapper its inexpensive part.
if this is not the reason then you need to adjust your water filler valve there should be a small screw on top of the pivoting float arm
if you have to adjust it for the water limit line inside the tank this will be the proper amount of water needed to flush once completely

also check that the chain lenth on the pull lever is not pulling the flapper down quicker than its supposed to,

try this let me know your results
hope it helps

Adjust the floating stopper in the tank to allow more water to fill the tank