NASA fuels space shuttle Endeavour for launch

* NASA fuels shuttle for 7:13 p.m. EDT (2313 GMT) launch

* Ship to deliver porch for space station experiments

* Fuel leaks, lightning thwart 3 previous launch attempts (Updates with start of fueling, weather forecast)

By Irene Klotz

CAPE CANAVERAL, Fla., July 12 (Reuters) - Hoping to end a string of delays, NASA will try to launch the space shuttle Endeavour on Sunday on a mission to deliver the last piece of Japan's Kibo laboratory to the International Space Station.

Liftoff is scheduled for 7:13 p.m. EDT (2313 GMT) from the Kennedy Space Center in Florida. Forecasters predicted a 70 percent chance the weather would be suitable for launch.

NASA canceled Saturday's launch attempt after a spate of lightning strikes near the shuttle's launch pad. Engineers spent the day checking the spaceship's electrical systems and other equipment to make sure there was no damage.

"We've seen nothing so far that indicates anything was actually affected by the lightning strikes," Mike Moses, the shuttle program manager at the Kennedy Space Center, told reporters after Saturday's postponement.

NASA managers met early Sunday to review the engineers' findings and cleared the shuttle for flight.

Shortly before 10 a.m. EDT (1400 GMT), technicians began pumping a half-million gallons (1.9 million litres) of liquid oxygen and liquid hydrogen into the ship's external fuel tank for the 8 1/2-minute ride into orbit.

Endeavour's primary cargo is a porch for Japan's $2.4 billion Kibo lab complex. The platform can be used to expose experiments to the open environment of space.

The porch is scheduled to be installed during the first of five spacewalks planned during Endeavour's 12-day stay at the outpost, a $100 billion project of 16 nations.

The space station has been under construction 225 miles (360 km) above Earth for more than a decade. It consists of nearly 26,000 cubic feet (735 cubic metres) of pressurized space, about as much room as a typical four-bedroom house.

The shuttle also will be ferrying a new crew member to the station. NASA astronaut Timothy Kopra will take over for Japan's Koichi Wakata, who has been aboard the station since March.

NASA had hoped to fly Endeavour last month, but the mission was rescheduled after hydrogen leaked from a vent line while the ship was being fueled for flight. (Editing by Jim Loney and Doina Chiacu)