91 RX7 NO spark no fuel No tach
 

First post.

Yes I have checked the internet and yes i know how to use a search button that is why I am here asking this.

To start things off I just purchased my third fc n/a at auction the other day and I am having trouble with it starting,

The car, 91 Fc Convertible
Here is my diagnosis.

It has 6 healthy puffs when i turn it over.

I am not getting wet plugs i have new ones ordered. but i have taken and sanded the carbon off the flat sections of the electrodes.

Not getting spark, I have Ohmed out my plug wires, ive tried traditional trailing and leading plugs along with a brand new ngk copper i use to test my other cars for spark with. no luck even a spark tester.

Next I am not getting fuel I have replaced the sending unit and pump out of my running rx7 it doesnt prime unless you jumper the yellow plug on the passenger side of the engine bay. along with that i have dumped 5 gallons of fresh 93 premixed into the tank the gas is still orange when i purge it out via the yellow connector.

My tach isnt bouncing when i try to start it, not even slightly. which would mean the cas is bad but I checked resistance like it said to in the fsm, it was around 150~156 which is acceptable. given the values in the fsm are 110~210 from the fsm

So I pulled the plugs,pulled the wires checked the coil packs and im not really getting a reading I am not sure if i am testing it right but I am going by the fsm I am testing the yellow and black wire for 12v with the ignition on. I am not getting any voltage even when rotating the engine. Should the coil already have a 12v since its triggered via ground?

My thoughts on this is that my cas is bad. Either that or my ecu isnt getting power. I cannot really find a way to properly diagnose the ecu. aside from grounds. If it helps when i turn the key on there isnt a check engine light or a just my washer light, and some other light. i believe my seatbelt.

I am going to attempt to pick up a cas from my friends turbo2 that he has taken out. that is a known good gas. but I am having trouble locating the red/yellow marks on my crank i can visibly see the marks but can anybody assist in marking them with a picture or what have you.

The Black/Yellow wires at the coils have voltage w/key to on. If it does not then you need to check the EGI fuse in the engine bay fuse box and also check the 15 amp engine fuse in the interior fuse box as well. The CAS does not control voltage to the B/Y wires of the coil as this is a function of the main relay.

Just went out and checked after looking at the ecu pinout. on 1b I am getting 0.19v and on 1a I am getting 11.82v which it should be I went and replaced the main relay with one i already had and I checked my fuel pressure (which i wasnt getting any before and I have 40~ +/- psi on start and while i was cranking it i still have no spark nor injector pulse.

I am not feeling the main relay click

I am getting a small amount of voltage on my lead coil b/y wire. not much but .01v nothing other than possible static

The engine fuse engages the main relay. There is a two wire plug at this relay which has a B/W wire and a Black wire. The engine fuse powers the B/W wire w/key to on. Does or does it not? If you were to check these things out as suggested you might find your problem.

I will try that tonight when I get off work and let you know my findings

After checking the voltage on the wires you suggested checking for the main relay, I checked them with the key on and I have voltage and if the key is off the voltage is 0, I didn't hear it click so I took the case off of my spare relay and tried to check them and compressed the relay and I got a click from my emissions. Clicked the other section and I didn't hear anything click, so I hooked my multimeter up to my coil and tested the voltage when I compressed the relay and I have 11v!

Attached is a video on what I did ignore the trailer park boys.

https://youtu.be/I7Vegx_35KQ

If the B/W wire in the 2 wire plug has voltage w/key to on then the B/W and B/Y wire in the 4 wire relay plug must also have voltage (the other two wires in this plug must also have constant voltage-no key necessary). Which does not occur in your situation.

I'm literally having the same exact issues. No spark, fuel or tach with no click from main relay so I swapped it with a known good one and still no click! If you figure it out let me know lol :lol:

Did you ever get it figured out? I have all of the same issues

sadly it's been 4-5 yrs since these guys last logged in. maybe try posting in the 2nd gen specific section.

also having same issue. Any ideas?

finally got mine figured out. I had a couple rusted and burned spots in my ecu not to mention every ground needed to be redone.

1990 rx7 convertible - grounds I fixed
-Cleaned starter grounds
-cleaned alternator ground
-Ground cluster behind passenger pop up headlight
-ground wire going from firewall to top of transmission
-ground on the drivers strut tower that comes out of the main harness
-fixed both battery cables
-sanded to bare metal the mounting surface for both leading and trailing coils. On the trailing coil there was a separate ground leading into the harness
-cleaned the ground going to the upper intake manifold (S5, I believe on S4s it’s underneath the intake)
-fixed the ground going from the far right ecu plug connector
-redid the ground cluster that’s located somewhere I believe to the bottom left of the ecu
-sanded the ecu mounting plate, inside of the ecu itself, and the floor where the ecu mounting plate bolts to.
-Tore apart the ecu and replaced any rusted and burnt pieces with spare parts I stole from my cruise control module and redid just about every solder joint inside of it.
-redid all the solder joints on the idiot light cluster on top of the dashboard (even got the clock to work!)

I also swapped a couple other parts from a working s4 earlier like the coils and wires, and the CAS.

and rebuilt the fuel pump and extended the fuel lines to run it in a clean bucket of fuel since my tank is full of rust.


good luck with yours!