when i turn on ignition i see 12 v at the circuit opening relay for the fuel pump ,but when i crank the engine the voltage drops to 0 volts at the relay

 

Share schematic?

 

Here's a schematic for a 2001 (it looks so similar to the one for my '94 truck, that I'll bet this one is 99% applicable to luci1957's Camry).
https://www.autozone.com/repairguide...6b43f8037894d#

When you say the voltage drops to 0 "at" the relay, tell us what you mean. If you're measuring the voltage actually at the relay, there are four pins, and each should have a different voltage. If pin 1, probably a bad ignition switch. If pin 3, could be a short in the wiring to the fuel pump. You get the idea.

Having said all that, this site is designed for Toyota truck owners. We're happy to help, but I'm sure you can find someone who knows a lot more about your rig.