What if all the Solo-jec 5 plus vaccine didn't go into puppy?

About 3/4 of vaccine went into puppy, 8 weeks old and puppy is very small does this make my puppy at risk?

There is a certain amount of vaccine necessary to trigger the canine immune system. That amount is the same for a Chihuahua as it is for a Great Dane and that should have been the amount contained in the syringe. I'm assuming you attempted to vaccinate the dog yourself? Well, now you'll have to at least call a vet and find out where you go from here. It would have been cheaper and way more effective to take him to the vet for his vaccinations.

Possibly. That said why are you giving the shots if you don't know how to give them properly? Stick to using the vet.