So, as far as I can tell, I've got an RX-7 that likes to run on air.

Picked up a non-running 1988 T2 as a parts car for a 1986 GXL, figured we'd mess around with it, see if we could get it running. First thing we find out is the fuel pump is dead. I guess here is a good time to ask whether the fuel pump from a N/A will supply the T2 adequately? To test, we replaced the fuel pump with the one from the GXL, also gave the T2 new plugs, new wires, full fluid replacement... And what happens is that it'll start, go for a bit, sometimes idle on its own, and eventually die. The turbo appears to be shot and definitely needs a rebuild, I think. Haven't taken it off to check.

Anyway, after the initial start, the RX-7 won't start again, UNLESS we remove the fuel pump from the tank, remove the lines, but don't unplug it, then let it burn what was in the lines, and then place the fuel pump back in the tank. At which point it will do the same thing, meaning not idle indefinitely.

Is it the turbo being shot giving it issues? I'd figure it'd at least idle, but I can't be 100% certain. Any thoughts?

 

An NA fuel pump will be able to start and idle the TII engine, but it will blow the engine under boost. The NA pumps have almost no flow at higher fuel pressures.

A blown turbo won't cause idle issues. When you remove the intake piping, check for in-out play and side-to-side play. There should be zero play in-out, and only a little side-to-side. If the wheel contacts the compressor housing, the journal bearings are done.

Idle issues are generally TPS or vacuum leak related. Did this car sit for a long time? If so, the fuel system will probably be in bad shape. Beside the pump, the filter and hoses may need replacement too. http://www.aaroncake.net/rx-7/unstore.htm

 

Thanks for the help! I haven't found any vacuum leaks, so I'm guessing it's going to be the TPS. Are they swappable between a TII and NA, or will I have to get a new TPS to see if it's the problem?

For the fuel system, the hoses appear okay and we cleaned them out, definitely going to replace the filter though. Going to have to find a TII pump somewhere though.

Another question I have is, do rotaries have something similar to freeze plugs like piston engines? We put coolant through the radiator cap to make sure it had some going through it since it's not pumping right away when it only starts for a little bit, and when we put in coolant, it just splashed down through the bottom cover. It didn't appear to come through the engine, as in seals blown, but I'm not entirely sure.

 

The TPS on a S4(86-88) N/a Or TII are the same.
So you can use the TPS on whatever engine.

 

There are freeze plugs on the back of the engine, facing the transmission. If one comes out, you'll have a coolant waterfall on the ground.

I'm not sure what you mean by this. You poured some coolant in when the engine was cold and running, and it overflowed onto the ground? The thermostat will be closed before ~180F, meaning the radiator is not part of the cooling system until that point. When cold, you won't see coolant moving via the filler neck.

When filling the cooling system, be sure to make use of the bleeder screw on the top/side of the radiator. Leave it loose with a rag underneath, and fill slowly until the level stays constant, and fluid starts to drip past the bleeder.

 

Been a while since I worked on the car. I managed to get the fuel pump, and found that the engine just seems to constantly flood. This led me to finding that low compression ie a worn/blown engine is the most likely culprit, so to forestall wasting money on more parts, I picked up a compression tester.

Now here's where I'm a bit confused. I tested using this method here and on the rear rotor it tested 32ish on each face, evenly, and overall was 91-93. So not too bad, old, but not too bad.

On the front rotor it was an entirely different story. Now, I can't tell if I managed to do something weird to my compression tester or put something in weird, but I did it multiple times and all I get is barely any blips, and an overall compression of around 10psi? Does that mean I'm doing it wrong, or is it really possible for a rotor to be that blown/worn out? Also what I find odd is that I can hear air being pumped out, and it doesn't sound that far off from what the rear rotor sounds like. Not sure about this one.

Thanks for all the help with this!