So for the past few years I've been looking into and learning about rotaries and RX7s. In this time I've spent plenty of time on Facebook marketplace and craigslist. Many times have I seen an FCs with a 13B converted to be carbureted. I don't understand why some one would swap to a carburetor over the stock fuel injection. I ask this because I found a very nice FC, but I am very uncomfortable with carburetors. Therefore I would also like to know whether it would be an easy conversion back to fuel injection.

 

I don't understand it either. At least on a streetcar. I think there were some racing classes years ago that wouldn't allow swapping the factory ecu for a standalone but did allow you to switch to carbs so that reason made some sense. I think those classes may allow aftermarket ecu's so even that no longer makes sense to me, but to someone who knows carbs maybe it does. As far as bringing it back to Fuel injection depends on which pieces are missing. I think it could get expensive sourcing the missing parts. Also could depend on haw intact the wiring is or if it got hacked up during the conversion. Might be best to keep searching for an intact fuel injected car.

 

When I bought my 1st car it had a couple Weber carbs on it. I asked what happened to the fuel injection and the seller told me that he put the Webers on there when the fuel injection had an issue and he didn't have the money to hunt it down and deal with it.

That was on an old Porsche 914, but maybe something similar is going on with that FC.. Simplification.

 

Carbs are hard to beat for simplicity and are easy to tune. The stock ECU is not well suited to a modified engine, and aftermarket ECUs can be expensive/complicated.

I ditched the EFI in favor of a Weber 48IDA on one of my GSL-SEs and it was fantastic. Total cost of about $750, would definitely not have had the same power/response unless the whole EFI system was swapped out.

 

The wiring harness would get brittle from heat and develop failures with amazing speed, in as little as five years. A used wiring harness would be about as likely to be bad as the one being taken out. So, people would do a carb conversion, as standalone EFI systems were either very poor, very expensive, or both.

How easy it is to return to stock depends a lot on how it was done and how easily you can find parts. As alluded to, OE wiring harnesses in good shape are basically gold unicorns, and a lot of the other parts are hard to find anymore too.

 

I don't know what the O.P. did about this car bought/passed it by but there is another option as well. It's a deep dive but one could get a standalone and unterminated harness and build their own harness. Get throttle bodies for whatever manifold style is on the car. Should end up better preforming than stock stuff or the carb. Problem is I'd imagine it would be overwhelming for someone new to both rotaries and ECU setup/ tuning.

 

That is why there were a large number of FCs running Haltechs and Megasquirts... get rid of the OE harness.