Dr. Shehzad Basaria of Brigham and Women's Hospital in Boston conducted a four-month trial in order to observe the effects of testosterone therapy on those with ejaculation problems. Basaria and his colleagues studied 76 men with symptoms of ejaculatory dysfunction, such as delayed ejaculation, inability to ejaculate, reduced ejaculate volume, and reduced force of ejaculation. All of these men had been diagnosed with low testosterone levels.
In the end, it was shown that testosterone therapy had no positive effects on those with ejaculatory problems, suggesting that low testosterone may not be the only contributor to such issues.
You can read more about this study here, and see the study itself, the results of which were published in the Journal of Endocrinology & Metabolism, here.