Help please - 8 month pup jumping and biting

Our 8 month old NI pup had always been very mouthy and bitey ever since we got him at 8 weeks.
We have tried to discourage him by giving him time out - either putting him in another room or leaving the room, which seems to work for a few minutes or an hour and then he starts again.
He gets lots of exercise, has lots of toys and bones and has been going to training classes from 11 weeks old. He is good at doing all the commands as long as he is not distracted by other dogs.
We have read all about bite inhibition and things like yelping etc just make him more excited and he thinks it is a game.
He is very excitable and jumpy and doesn't seem to settle even when he is tired. He has had a behaviourist out who recommends time out but it is not getting him out of this biting.
Is there anything else we could do to get him out of this as he is 5 stone and it really hurts now he has his adult teeth. We are bruised and I think he could draw blood if he doesn't stop soon. He only does it to us, not to other people. We are doing all the pack exercises to show him we are the pack leaders ie sitting for everything and going through the door first.
He was neutered 2 weeks ago which we hope might calm him down as he is so excitable. He is very friendly and loves people and dogs and he will be fantastic if he calms down a bit and stops biting.
I don't know if a spray collar might be worth a try as we don't know what else to do or if he will just grow out of it eventually. It is not aggressive biting but it is a problem as even playing with him with his toys ends with him preferring to chew us so distraction with toys and bones isn't working either.
Any advice would be appreciated as we are lost for what to do now and it is affecting our lives as we can't sit down without being bitten.

Thanks

I forgot to say we tried the pet corrector which has no effect at all as he wasn't bothered about the hiss and a personal alarm which does seem to interrupt him but then he thinks it is a game and starts again.

Hello Heidi and welcome to Dogsey
When you say 'putting your puppy in another room', I can never see the point in this, by the time you have got the puppy into the other room it will have forgotten the incident, so will actually be learning nothing at all.

Play biting is normal behaviour, puppies do it when teething,to explore the world and during puppy play and they do grow out of it to a certain extent. It is a good idea to teach your puppy to bite ever more gently so that when he has adult teeth and jaws should he ever bite he will not hurt anyone and this is 'bite inhibition' . Don't expect it to work instantly, it will take time particularly now your puppy has been allowed to continue with the unwanted behaviour until 8 months, teaching bite inhibition should be started when the puppy is very small. Also you need to be consistent, patient, stick to one method and everyone in the house needs to adopt the same strategy.
Here is a link to teaching bite inhibition.
..click here

Can I also ask what you are feeding your puppy? Does it contain lots of additives.

He is on Burns mini bites and gets egg and chicken breast as extras or for training treats. We have been doing what we were advised to do since we got him but he has always been extremely mouthy and sometimes the pressure is ok, but when he jumps and bites the pressure is hard.
His dog etiquette is good and he does not bite other dogs like this so I am not sure why he does it with us. He is quite strong willed and in the teenage stage so it could be part play and part pushing his luck. We don't worry about him with other people as he doesn't do it to them or if he does it is very gentle.

Heidi it does sound as if you have tried lots of things which will be very confusing for your puppy.
Have just noticed to say you can't sit down without being bitten, is he jumping up when you sit down?

If so you need to calm your excitable puppy while making it clear to him you are not going to play, his bad behaviour will not get your attention. So if he jumps up when you are sitting down don't look at him or make any eye contact, stand up with your arms across your chest and turn your back on the puppy . Again everyone needs to do this every time he does it with no exceptions and it will work.

When your puppy is sitting down and being good don't forget to speak to him calmly and give lots of praise so that he learns this is good behaviour that pleases you and he will learn to repeat it.

He does jump up and mouth. He tends to launch himself sometimes. If we keep still or turn our backs he just keeps doing it so we have to move to stop him. It can't be for attention as he does it even when he is getting attention and we are playing with him.

We have had 4 GSDs in the past and helped a rescue and I have never seen anything like this before and we have seen a lot of dogs in our time.

Heidi he sounds a good puppy and well socialised with other dogs. If you read the article I posted on BI and stick to it you will get there.

At 8 months yur puppy will be experiencing a surge of hormones too, neutering will not alter that because the hormones will still be active for some time.

I don't think your puppy is pushing his luck, he just hasn't learnt what behaviour is expected of him. Dogs repeat behaviour that brings 'a reward', the reward can be treats or your attention. If the behaviour brings no reward it will eventually die out.

The food seems ok, Burns is one of the better complete foods.

Heidi do you/others speak to him when you move which is still giving him attention .I would not move or /speak/look at him until he stops, he has to stop sometime. When he does tell him he is good, if he jumps up turn away again and he will learn what you mean..jumping up brings no reward.

it is play/a behaviour that he finds rewarding both when you are already playing or if he tries to initiate play with this behaviour and it has become a habit because it has not been consistantly checked.

I can only suggest that you try the methods described above and stick to them. Don't expect instant success particularly now he is older, only time and consistency will make it work.

Can I ask a few questions, how much exercise does your dog get each day? Is it off lead free running, chasing a ball or similar or a walk around the pavement on lead?
Do you reprimand him at all when he jumps? I know you said you turn your back and ignore him but do you actually sternly tell him to "Get off".? With the mouthing do you tell him "No biting" in a stern voice?
I do know how difficult it can be with a large young bouncy dog jumping on you mine took a while to cure but I got there with a bit of help.

One of mine is a great jumper-upper still, although her sister isn't. Rattling stones in a bottle worked for a while but then she got used to it and ignored it so I have gone back to squirting her with water and that does work. As has already been said turning your back works as well as mine eventually sits and waits for me to turn around and then she is praised. I always take the washing up liquid bottle out with me and the minute she goes to jump I shout NO and squirt her, so she is beginning to stop it now.
I have tried all the other techniques including the citronella collar, all worked for a while and she stopped and then started ignoring whatever deterrant I had in place. Luckily I have never had a problem with mouthing or biting, they do that to each other!! However squirting with water works every time as she hates water on her face.