My 2001 honda prelude just started pouring oil from front of engine behind crankshaft. what could it be and how do i fix it

That would be the crank seal that is leaking.

1. Before servicing the vehicle, refer to the precautions in the beginning of this section.
   
2. Disconnect the negative battery cable.
   
3. Safely raise and support the vehicle.
   
4. Remove or disconnect the following:
   
   • Splash shield
     
   • Engine accessory drive belts
     
5. Turn the engine to align the timing marks and set cylinder No.1 to TDC. The white mark on the crankshaft pulley should align with the pointer on the timing belt cover. Remove the inspection caps on the upper timing belt covers to check the alignment of the timing marks. The pointers for the camshafts should align with the green marks on the camshaft sprockets.
   
6. Remove or disconnect the following:
   
   • Upper timing belt covers and crankshaft pulley
     
   • Lower timing belt cover
     
   
   NOTE Mark the direction of the timing belt rotation if it is to be reinstalled.
   
   • Timing belt
     
   • Crankshaft Position (CKP) sensor from the oil pump, if equipped
     
   • Stopper plate
     
   • Timing belt sprocket from the crankshaft. Do not lose the sprocket key.
     
   • Seal from the front of the engine, using a suitable seal removal tool
     

1. Clean the seal mounting surfaces on the engine block.
   
2. Apply a thin coat of grease on the crankshaft and seal lips.
   
3. Install or connect the following:
   
   • Seal with the part number facing out. Use a seal driver to seat the seal against the oil pump. Clean any excess grease off the crankshaft and be sure the seal lip is not distorted.
     
   • Timing belt sprocket and key to the crankshaft
     
   • Stopper plate and if equipped, the CKP sensor to the oil pump. Tighten the stopper plate and sensor mounting bolts to 108 inch lbs. (12 Nm).
     
   
   NOTE Verify that the engine is at Top Dead Center (TDC) for the no. 1 cylinder on the compression stroke.
   
   • Timing belt
     
   • Timing belt covers and crankshaft pulley. Tighten the crankshaft pulley bolt to 181 ft. lbs. (245 Nm), with the aid of a crank pulley holder.
     
   • Accessory drive belts, then adjust.
     
   
   NOTE Verify that all engine components that may have been removed have been reinstalled correctly.
   
   • Splash shield and lower the vehicle.
     
   • Negative battery cable
     
4. Top up the engine oil if necessary.
   
5. Run the engine and check for leaks.