Bleeding Hell!. Can't get no pressure on front brake!

[scorcher]

Got punted off my bike a couple of weeks ago, by my following mate , right outside a carpark where Dorset's finest were holding a Bikesafe day . Anyway, after sorting things out thought it was probably best to get on home, but found I never had any front brake pressure so came on steady on the rear brake. Have tried bleeding it several times, but it's a struggle to get any brake pressure and when I do, it's only temporary. If I keep the brake held it comes back to the handlebars and then won't hold. I can pull it again and get some pressure but again it will fade if held. I've pushed the pistons in the caliper right back and even struggled getting those to come back out again. Also , when I release the brake lever I'm getting bubbles coming back up into the master cylinder or it will spit brake fluid out over the top.I've let fluid just run through the system with out pumping the lever and there was loads of air in there.I've tried an easy bleed thing and I'm struggling to push fluid throughand even doing it the old fashioned way I just seem to get more and more air. I'm beginning to think I have problems with the master now as the bike came down on the handguard and then the brake lever. Tried reverse bleeding but the syringe/tube wasn't sufficent for the task. Tried cable tieing the lever to the grip when I have pressure but it just goes soggy again.
Bike is a KTM 690 SMCR. Any thoughts from the mechanical experts?

[billinom8s]

Have you removed the brake line? Might fine that when it hit the ground the line got moved and is now allowing a little air in through the banjo bolt, check tighten them.

Do you have a spare lever? May be worth pulling the old one out just to make sure there's no damage to the master cylinder.

[Ruffian]

Sounds like the plunger in the master could have a bend on it

When pulled in through its range of travel is actually twisting and drawing air through.
If you pull the brake pipe off the caliper and put it into the master reseviour then keep pumping it will push all the air out. This way it wont get pressure but can see if it pulls air in then you know you definitely have a problem.

Also dont rule out the brake line as could have a small kink in it which may hold pressure on but doubtful it would pull air in unless damaged the copper washers

[Buggs]

You msy have a hairline crack in the caliper, stumped me when i piled my ktm into a bank same symptoms wouldn't let fluid out as such but would let air in, id only just done the master so was confident it wadnt that. Worth doing the seals in there first only 10 min job, if you back blead them you'll see a leak elsewhere easier