87 mr2 starts but blows the efi fuse - 1987 Toyota MR2

check for a dead short in starter relay , wiring etc after the fuse

you may have a short of some kind, when a fuse blows repeatedly it is no good just replacing, you are being told that something is wrong with the equipment.
You will almost certainly have to visit a technician for a diagnosis. It is unlikely to be something that an inexperienced end user can sort out I am afraid.

GOOD LUCK

It is not related to car being cool down , I think you are having ignition switch on . The EFI fuse goes directly to the contact switchin the EFI relay. Maybe try removing the EFI relay, turn the ignition to ON, and see if the fuse blows.
Doing this, the car won't start, but it might give you a clue as to where the short circuit is located. ... Check the fuse/relay box next to the driver side fender in the engine compartment.

there is a short in a unit or wire that the EFI unit runs. It may even be in the EFI unit itself. Insert a new fuse and run the fault codes to determine if a fault has been recorded.

A little bit of gas in your carburetor and change the spark plug that you should be golden

There is only ONE reson why a fuse blows: Something is overloading the circuit and drawing more amperage than the fuse is designed to handle. This is what is known as an "overload" or a "short circuit".

Plesase read the following two articles:
Where's the fuse?
What else could be wrong?

If after reading these two articles, you think you would like to try your hand at tracking this down and fixing it yourself, and you are sure you have the correct equipment (as listed in the articles), let me know and I will help walk you through it.

EFI (electronic fuel injection) is a nasty fuse to blow. Unplug EFI module for 5 minutes. Plug it back in and try to start it immediately to confirm a heating short or possible bad module.

I had the same problem with my 1990 P/u. It turned out to be the O2 sensor touching the underside of my box shorting and blowing the EFI Fuse

you can try a bigger fuse and if it still blows it then you have a short in one of the wires. i then you will have to hunt down the short that can take awhile.

The EFI fuse is for fuel components, and for powering up the ecu. There is a lot on that circuitry. The 15 amp fuse, is also the power for the EFI relay. If this relay is without the power from that fuse, you probably won't have the fuel pump working, and the ecu won't be fully powered up.
Check the fuse again to see if it blew out again. If it did, you will have to trace the circuits for a short. Also, the EFI fuse gets power from the 40 amp AM2 fuse, so if the EFI fuse has power to it, the AM2 fuse is okay.
If I were you, I would test and check all fuses in all fuse/relay boxes under the hood. checking fuses is easy with a cheap test light. With the key in ON, every fuse on the car has power to it. So you clip tester light to ground (use neg. batt'y post), and then use test light probe into the little slot on the top end of a fuse. You do not have to take fuse out to visually inspect.
On the top end of all fuses are 2 little slots (one at each end of fuse) that is open to the metal strip inside. So you turn key to ON, then probe one end of the fuse. The test light should light up. Even a blown fuse will light up tester on one end of the fuse. Now to test the fuse itself, use the probe and touch into both ends of the fuse. A good fuse will light the tester on both ends of the fuse. A blown fuse will only light up one end of the fuse-the metal strip has blown so no power on both ends of the fuse, SEE?
And by using the test light, you also verify that power is getting to
the fuse. It is easy, and you are on the way to becoming an automotive electrician. Next, you need to buy and use a multi-meter, for automotive uses buy a digital volt-ohm meter (DVOM), which is what most multi-meters really are. And you don't have to buy an expensive one. I have a Sears Craftsman DVOM, about 20 years old, and it only cost like $30.