1992 Toyota Corolla Repair Question
Mileage: 145,000 miles.
The cars blows the efi fuse
Answer
The pump is not a likely suspect. If it shorts, which is real uncommon, it will always be shorted and will blow a fuse instantly, not after 20 minutes. Pumps usually fail when the brushes wear away and create an open circuit. Open circuits result in no current flow. Fuses blow from too much current flow.
A more common cause of too much current is a grounded wire leading from that fuse. Harnesses that slide back and forth on the body sheet metal as the engine rocks back and forth, wires draped over a sharp metal bracket, and wires that fall off their mount and onto hot exhaust parts are common causes of grounded wires. Component failure should be suspect too but things like that are hard to find when they act up so intermittently. A simple trick to finding a short is to replace the blown fuse with a pair of spade terminals, then use small jumper wires to connect them to a 12 volt light bulb. A brake light bulb works well. When the circuit is live and the short is present, the bulb will be full brightness and hot so be sure it's not laying on the carpet or against a plastic door panel. Now you can unplug electrical connectors and move things around to see what makes the short go away. When it does, the bulb will get dim or go out.
i did check the injectors which were in spec.i looked at wires in the engine compartment and the interior which which most are covered in black wire loom and didn't see anything touching.i do have a code 24 which is the iat sensor/circuit.though the check light is not on.i read that the iat sensor has something to do with sending information to the efi circuit.i checked the cor which seemed to be working though i don't think the cor has to do with fuses blowing.
EGR VSV, Air control valve VSV, Ciruit Opening relay and fuel pump shares the EFI fuse. Any of these are possible causes.