How do I fix an electrical outlet that tests ok, but does not work with larger appliances?

I have three outside recepticles that all are wired correctly (I have checked) and that all have voltage. No circuit breakers are tripped. I can use a clock-radio in each outlet with no problems whatsoever. However, when I go to use the outlets for a power drill, an electric hedge trimmer, or even Christmas lights, the outlets do not work. There is no GFCI switch being tripped. I appreciate any help!

Note: I have tested the outlets for wiring problems already using a recepticle tester. I have also used a voltage tester (in addition to the clock radio) to assure power to the outlet.

Thanks for the assistance to date. I did as suggested, and tested each of the outlets. Believe it or not, the three problematic outlets are spread over two different breakers / circuits. And, when I went home tonight, I put the most current heavy appliances I have on 100ft extension cord to maximize resistance and all of the outlets worked! Great in the short term, but I am still confused as to the real problem. I would agree it could be a breaker, except for the fact that the problems are from two different breakers. Again, any suggestions are appreciated.

If you have approximately 120 volts between the hot and neutral wire at each receptacle then it sounds like your circuit is ok.

I suspect your receptacles are old and worn out. I recommend replacing them. If you replace your receptacles, ensure they are GFCI protected.

Your voltage needs to be within 10%.Find the exact voltage. If that tests o.k. then replace your breaker.

I've had this problem before. You're getting enought voltage, but not enough amperage. If it was the outlet, you would probably get arcing and be able to smell it.
When this happened to me, it was the circuit breaker. Take out a good breaker of the same size elsewhere in your breaker box and put it into this circuit. Then try it out.
BTW, turn off the main breaker to the house before taking the breaker box cover off.

put a 220 volt outlet for larger appliances like washer or dryer.. instead of standard 120V?

I agree with Dave. It's probably the breaker. The breaker may be bad or not large enough. There is a small possibility that it could be wired wrong somewhere or that the outlet is just not meant to handle a very big load.

You need to check out the specifications for your breaker, what gauge of wiring is run, and how much of a load you have running on that circuit. Are their other appliances running on that circuit? It sounds more like an amperage problem.