Why can't he cum when I give him a blow job?

First I love a girl that loves a mouth full of cum... I gotta tell you that is a great quality. The guy may feel deep down that it is disrespectful to you and really cares about you, so tell him that you enjoy his come down ur throat and ask him to please unload on your tonsils and he may just come around.. haha that was a pun. Take care and hang in there, also maybe when he is close, use more hand and less mouth, and let him shoot in ur mouth. That may also be beneficial. Hope I helped. I am actually very horny now after telling you all this.. haha. Talk later

Dominate him physically and psychically. Own him. He is yours.

Dear Challenged, find out if the guy who doesn't is using some type of herbal stimulant or Viagra because male sex enhancers limit a guys ability to come no matter how good the blow job. But he may be better off not cumming in the long run. If you have a moment read my blog listed and scroll down to the article "The Power of Sperm."

For what it's worth:
I read a statistic saying that 75% of the guys don't come from a BJ.

It happens all between the ears: a guy who kicks on domination over a woman will get much more turned on by a BJ than a guy who doesn't.

it all depends on his size... does he look at you while your on the knees?

It sounds like an issue on his end. Make sure that he feels comfortable enough to tell you what he likes (not that it is necessarily your job, but since you are the one asking the question.). If you are doing the things that turn him on, then he may just have a mental block or some other frustration that is preventing him. He might be having trouble relaxing for some other reason. On the other hand, he might be relaxing so much that he can't build up the intensity to cum. There are really a lot of factors that could be involved and most of them are on his end. I would recommend talking to him specifically.

Also, the fact that you love making guys come in your mouth. well, I cried tears of joy when I read that.

If he's like me his past girlfriend didn't like it & he always he's it back. Now he has to change his way of thinking & let it go. Do tell him to let you know by either saying I'm cumming or a tap on the shoulder. You guys decide the signal if you want one at all.

NICE! I'd like to say thanks for answering my question first.
Now for your question. In a previous question, I said that oral sex for a guy is not about the position it about the technique. Well, different techniques work for different guys, but there is one trick that is absolutely sure to work. Like a woman's clit, the tip of the penis is a massive collection of nerve ending (half the amount of the clit though), if you play close attention to the tip of the penis, he'll cum hard.
In a better understanding of what Men go through during oral sex. Things like putting in all the way in your month or playing with our balls, these are all psychological turn ons that result in physical pleasure, but the cu de gra as you might put it is the tip of our dicks, that is purely physical pleasure, which still requires a bit of tech to get it right. I say practice on him, and you'll get a mouthful soon enough.

I myself have this problem I had a girl blowing me for 45 minutes and gave up 'cause she got nothing then again I had a girl rubbing me and massaging my head with her tongue then deep throating to keep lubing my shaft it was hot it still took a while but she eventually got me off, just try experimenting with him if he has to rub himself to blow in your mouth try rubbing for him or lock your fingers between his and double team his shaft just do something different surprise him next time you go down on him and I bet you will see a different result, another method I have had done is the girl used a little warm water in her mouth while blowing me which was a little weird at first but felt amazing when she really got going, the key to getting the result you want is just experiment if he starts bucking into the back of your throat you know your on to something, just mess around with different ides and you'll get there.

Guys are all different and he might just be less sensitive, but I did once have a boyfriend who told me that he thought cumming in a girl's mouth was degrading. He said he couldn't do it unless it was a girl he wanted to degrade. Which was kind of messed up because when he got back with his ex who had hurt him he had no problem, but with me it was impossible.

Use a combination of manual masturbation and oral stimulation! Experimentation is the key. I guess men are just as different as women when it comes to orgasming.

Well you know, every guy is different, and I've found that guys who have a lot of stamina during sex take longer to orgasm during oral, too. My advice? Start out having sex, and once he's getting along, go down on him. That should give you a better shot.