Ok so I have a '74 RX-4 with a 13b GSL-SE FI motor in it out of a 84 RX7. I got the car running today and I took it for a drive down the road.

I had been driving it for 10-15 minutes and it was running great. I hit a bump in the road and the motor died.

I found it was the fuse that feeds the main relay had blown. So I put in another fuse and it fired right up and drove another 10 feet and died with the fuse blown again. I then put in a third fuse and as soon as I started cranking the motor over the fuse blew again.

So I have blown about 6 fuses now. Everything has power until I crank the motor and then it blows the fuse and won't start. I tried jumping the connection with a wire and the motor started for about 10 seconds and then the circuit opening relay went "eeeek" and smoked and the motor died. Please help! What could be causing this?

I am pretty sure its a short somewhere but I dont know where to check exactly being as the fuse is fine and everything is fine with power until I crank the motor then it blows the fuse immediately. PLEASE HELP!
I have a wiring diagram but I cant think of what would cause it and I checked quite a few things already. Thanks.

 

Tie your battery down so it stops hitting the inside of the hood?

You've had something bounce out of place and cause a high-current short, or a wire has gotten pinched & the insulation cut through. You need to isolate, visually inspect, & correct the short.

Since it's happening when you turn the key to "Start," you can probably work backward from the starter; disconnect the starter positive lead, insulate it so it doesn't touch anything, and try again. If the problem doesn't happen, the fault is in the starter. If it still does, it's further back, like in the solenoid or the start lead.

If you had experience with using a VMM, you could instead disconnect the battery and then keep isolating things until the resistance rises.

 

Would a bad ignition coil or ignitor cause this?

 

It was a short in the wiring feeding the power to the ignition coils.

Anyone have any old school 13b's laying around that they want to sell?
I want to go with an original 13b

 

the 74 never had a option for a 13b only the gsl-se's

 

REPUs from '74-77 had the very first 13B engines, perhaps that is what he is referring to.

 

if he wants to go carb why not just take the ecu and FI gubbins out and put a carb on? why go through with a full engine swap? given you can fix that ignition short.

 

The 1974 RX-4 I have originally came with a 13b. I was wanting to find an engine that matched the car.
How hard is it to change the GSL-SE engine to carb? Is there a big difference on how they look on the outside?

 

Very easy. Looks way cleaner and cooler. I have an 86 6 port 13b in mine on carbs and love it

 

basically all you need to do is get a carb and manifold. there may be something about ignition but i think thats still dizzy and coil operated the rest of it is just running the fuel line and removing the FI pipeing and the ecu.


im sure someone with more experience can tell you the exact steps to do it. hell i bet you could even sell your FI system to help offset the carb and manifold you may even make money

 

Check grounds. I swapped a motor in my honda. It did this exactly. Turns out I bolted a ground down, but didn't tighten it... so when I hit a bump, the ground would kill
the engine