Ok, I have a question. I recently bought another 1986 Rx7 fc GXL it is very clean. It has one owner and it has 44k original miles. From what I was told the car stopped running at a random time when driving. But from what I know it just a fuel pump issue right? But the issue is the previous owner changed the fuel pump. And it still does not run.

He let me know that he did take it to an electrician and he told him that the CAS was the only thing wrong with the car. But I do have another running 1986 Rx7 fc and I changed the good CAS from that car into the other one. And I still got nothing. (Forgot to mention the electrician told the previous owner that the injectors were getting no electric pulse). So I took off the manifold and I inspected those injectors and I changed them with the known good ones from the other car. And I still got nothing. So I read forums and they mentioned to me that I had to change the resistor pack. And I changed it with the good one again. And it nothing. At this point I had no idea what was wrong. So someone mentioned to me that maybe it was the computer and I changed it aswell and nothing. I also changed the AFM but did not hold it open and I got nothing.

Any thoughts?

 

How are the engine grounds?

maybe this thread will help:

Help with Crank Angle Sensor - RX7Club.com - Mazda RX7 Forum

 

Did you check the EGI fuse in the main fuse box next to the battery?

 

basically if you take a spare CAS plug it in, and spin it by hand with the key on, you should hear lots of clicks from the injectors and spark plugs.
if not, then you'd maybe start by making sure the ECU has power

 

Well, since I made the thread i have lots of updates. I did make sure to read other threads and learn the common mistakes and mishaps of what 13bs usually fail. But at this point I don’t know what could be wrong.

For example:
- All of the fuses were checked and changed from another fc that had good ones (same year)

- Someone suggested I change the main relay and I exchanged it from the other car

- I did try to open the AFM while cranking and nothing happens

- I suspected there might be a break in the wiring harness but I checked the injectors when key is ON and it’s receiving 12V and I took off the throttle body and cleaned all of the grounds (that I could see)

- I changed ECU from other Fc and nothing happened

- I replaced the injectors with known good ones - unclogged and nothing.

- after changing the CAS there is a tachometer bounce when cranking.

- right after checking the injectors I suspected now it wasn’t receiving file or it might be clogged so I changed the fuel filter. and still nothing

- it was suggested to jump the fuel pump and I did but still nothing happened..

- I did open the fuel like multiple times and there was no fuel pressure coming out. Both primary line and secondary.

- I changed the resistor pack early on and still changed nothing.

At this point I’m not too sure what is the problem anymore. If I could get help it would be greatly appreciated. There is some things that might be the cause:

Things to note:

- When the key is ON position one of the fans turns on immediately. I checked and people suggested that the sensor might be faulty or a ground. I have yet to resolve this issue.

- after some time the key being in ON position a certain humm comes from the inside. People suggested it was the coolant sensor. I have yet to try to solve this.

- and lastly, I suspect that the apex seals might be stuck because it has sat for some time. But the weird thing is that the car starts when you spray fuel down the throttle body. So I’m not sure if they are or not.

At this point I don’t know what to do. Any suggestions?

 

Have you checked for power at the pump? If you’re jumping the test connector it should have power with key on. If it does and you don’t have fuel pressure it’s either a pump or a screen or it’s leaking around the seal where the pump connects to the fuel lines.

 

Since the other owner let me know he changed the fuel pump I did not check it. I will make sure to. But I’m unsure if it is the problem given that he was a mechanic. Another thing, if the pump is cheapy could it stop it from running?

 

I mean it depends on how cheap is cheap, do you have a copy of the factory service manual? In it there’s several ways to test your fuel pump to be sure it’s actually performing if you’re worried about a subpar pump. It’s possible the pump is fine but a relay or connection isn’t. For lack of technical terms, the pump has a nub on it that seals into a bell shaped piece of tube with an o ring to transmit fuel pressure into the system, I had issues with mine leaking fuel pressure back into the tank which is something you can’t really tell until you test or try and pull it out.

 

I mean, since I have another car that runs completely fine what I will probably end up doing is just trying the other pump in the GLX and see if it changed anything.

 

yeah, be sure to check voltage before swapping in case that’s the problem

 

Ok, some updates. I checked the fuel pump. But the fuel pump hangar had no screws whatsoever. I’m hoping that’s the issue to my no fuel pressure.

 

I am not sure no screw would cause your issues, I am siding with no. It is a major safety hazard though.

Check for busted screws. If there is empty the tank and let it dry. You can the drill and tap the broken ones.

Don't forget the gasket between the tank and the assembly. Also, there is a yellow connector, in s4's anyway, near the air box. Bridge the pins, remove the fuel line from the filter to the engine at the engine. Drop the hose into a glass jar after refilling some or all of the fuel tank. Two people help, with a fully bled system and a quick bump of the key, you should have fuel in the jar.

If not, it is time to learn schematics. I have seen where people rewire the pump where it bypasses the safety system. If you get in a accident it can spray fuel everywhere. Making a bad situation mich worse. Don't do that.....

Also, check your fuel sock on the pickup near the pump in the tank. Those get clogged and cause issues. As the poster mentioned check for leaks at the pump. It is very cheap to replace the lines when you are in there. Just get fuel injection rated line.

 

I want to thank all of you for such a great help you have been. After countless hours the car finally started. What it turned out to be is that the previous owner lied to me about him changing the fuel pump. I changed it with the one from my other car and it started right up. With some goodies (the 13b might be ported &#128513

-this is what the pump and hangar looked like-

 

Nice..... Hopefully the previous owner didn't pay someone to replace it and got that.

With that much rust, I would flush the tank really well and refill. Also, try to pressurize the system and check for leaks.

Best wishes with everything.

 

Yikes! Do you know how long the car had been sitting since it last ran? I would guess years/decades with that kind of rust in the fuel tank.