Several ways to make blood gush from a wound... By the way I'm not an experienced make-up effects artist, I just read books and think about what I would need to see to make me believe this is real.
Blood as established, Karo mixed with red food coloring, I add a little blue to give it a dark look. Also I'm not sure but I believe your best bet is to go with the clear karo syrup, not the maple house kind you use for pancakes, although it could work too.
For some cheap effects on blood gushing you could buy some condoms, yes do not be afraid! Fill them with your blood mixture and tape them to the victim’s body. This works best for stunts where the actor is wearing clothes and the skin isn't revealed, you could easily walk up to the person and pop the bag. Although you should be very cautious especially if attempting to cut the bag with a real knife. This technique actually works with different stunts as well, like Last House on the Left, the women who falls in the pool gets her throat cut, but what actually happens is under her shirt is a bag filled with blood, when the actor appears to cut her throat the women pops the bag and the blood shoots up, looking as if she really did cut her, good stuff.
Intestines, well yes you could always use real ones, but that’s kind of nasty to me, anyway...here's my take. Buy some more condoms, or well rubber balloons, what everyone you want. Fill them with peanut butter and jelly and connect them all together, soak them in some of your blood mixture and there you have it. Not sure if it's a good effect, but it's worth a try.
Also some of the greatest effects can be achieved right at your very own home. Suppose you are filming a scene where zombies are eating, well take some left over chicken mix it around in your blood mixture, if you really have some money to spare you could do it with steaks also. So you see it's really not that hard, just think what would you have to see to make you believe it's real. Also tubes come in handy as well, just tape them to the victim or what have you, make sure they are concealed and just pump the blood through. There you go that’s my take.