FC S4 NA Changed Alternator Now Won't Start
 

1986 automatic - running prior to changing the alternator. No 'mods', just went from running to not running. Not flooded, getting spark...at a loss. All I did was disconnect the battery, pull the old - add the new, re-connect the battery. Has new fuses for under the hood and new plugs. Please help, didn't find an answer searching the boards. Would something have shut off the fuel?

Are you sure it's not flooded? Are you getting fuel to the engine?

^ What he wrote, and also:

Don't overlook the obvious:
-> Are the battery cables correctly connected to the alternator? Because as far as I remember (I may be wrong) S4 alternators have 3 terminals.
-> Is the new alternator also from a S4? Or is it from a S5?
-> Have you tried putting back the old alternator and see if it works? If it does, then the new alternator may be faulty or not the same as the old one.

I have gone through both of the de-flooding procedures. When I pull the plugs after trying to start it there is a little fuel on them, slightly wet and smells like gas.

Is there something else I can do to ensure it is in fact 100% not flooded besides the tow different de-flooding procedures?

Battery cables are connected to the alternator. It came off an 1986 non-turbo, would it make a difference between base (mine) and a GXL?

Going to put the old on tonight or tomorrow ... was hoping to get it going today :)

On the S4 alternator there is the clip in the back with two wires (looks like a T) for the R and L terminals and the hot from the battery. The 'leftover' terminal being 'F' and I call it leftover because I do not recall unplugging anything from there nor can I find anything in the FSM that shows a use besides testing.

Doesn't matter what S4NA your battery cables are from, all are the same. But at the same time, I'd bet good money that one of them is the culprit. 25 years of prior-owner neglect really takes its toll on them.
Check the voltage on the positive cable at the starter. If your battery is reading 12.6 (full charge), voltage at the starter should be no lower than 12.5 when not cranking. If it is lower, your cables are the issue.

Ideally, you should de-loom the Engine Harness and extract the battery cables from it. Clean them up and/or replace per Aaron Cake's grounding article here:
http://www.aaroncake.net/RX-7/grounding.htm

Removing the positive cable is a minor annoyance due to the splices for the Alternator and Fuse Box. What I did was snip both at the large cable and give the fuse box input cable a suitable ring terminal or lug. 4 AWG cable should be used for the alternator and starter. Lengths are 24" from battery to alternator and 48" from battery to starter. Battery negative to chassis ground is 24", same for chassis ground to starter. Your positive terminal will now have three lugs on it: Starter, Alternator and Fuse Box. Good reason to get Marine Battery terminals.

The "T" connector on the back is so the Voltage Regulator can see what the alternator is doing. That is the "R" terminal on it. The "L" terminal is what turns on the warning light when voltage is too low.

The alternator, not the battery cables, came off another RX7. Good post though, will be doing this soon.

Put the old alternator back in and it is a no go. Didn't start. However, I did notice that the connector ion the back of the alternator that the top terminal wire popped out the the clip...so, I am going to fix that problem in the morning.

In the FSM it clearly states NOT to start the car with that disconnected which technically, it was. So, what damage may that have caused ? ? ?

You seem to be going in the right direction. Checking cables and their connections is always a good thing to do.
About the damage, I don't know what might have happened. Maybe someone else knows what can happen in those situations...

Good luck.

The car will start w/o an alternator as long as the battery has a sufficient charge to it. When replacing the alternator did you accidentally do something to the Water Thermosensor connection on the back of the water pump housing? Damage to the sensor and or connection "could" cause a hard start. And have you tried using starter fluid to get the car to start briefly? Also, make sure to doublecheck the 15 amp Engine fuse.

I thought the car would start w/o the alternator - wasn't sure it the rotary was different. Will check the fuses again the thermo sensor - where is the best place to spray a bit of starter fluid ?

Damn, I'd recommend a push start but it's automatic. Push starting is the easiest and least BSful way of starting a flooded rotary.

I got an automatic na because the boy will turn 16 in a few years and have been going over how to maintain the car - go figure, now i am stumped. Good lesson for the both of us:)

Next one will be a t2 5 speed...

The air intake duct on top of the radiator. It's best to do it with the fuel pump disconnected so if it fires up briefly then it should clear out the housings of excess fuel. Do this a couple of times if the first attempt to get the car to start works followed by reconnecting the electrical plug to the fuel pump (located in the rear of car) and then try to start the car in a normal fashion.

Didn't get a chance to try and start the 7 today - tranny went out in the wife's truck...but Ford is paying that bill :) But, that thermo sensor connection looks BAD.

Can they be repaired or just buy a new (new to me) one?

Also, thanks for the quick reply's - you guys are awesome. I'd rather have a non-starting rotary vs. a running Honda any day.

Pin 2I (Green/White wire) of the ECU is for the Water Thermosensor. The pin should read 2 to 3 volts w/key to on on a cold engine and .4 volts w/key to on on a fully warmed engine.

My mechanic buddy told to look behind the passenger kick plate for a button that may need to be pushed...look in there, didn't see this 'unicorn'. Is there another location for this 'reset button' ? he told me that he had a simliar issue with getting spark, fuel an air/combustion but it wouldn't start until he press the button.

I wonder... Is he talking about the circuit breakers on the fuse box?

I have checked everything under the sunrise red - tomorrow morning will make sure the oil is topped off and after that...I guess I'll start all over again.

Is there a 'reset' on the circuit breakers on the fuse box? I have searched around but haven't been able to find anything.

http://mazdarx.narod.ru/manual/CIRCU...s/85816080.gif

Looks like this? Going to try this tonight or in the morning.

Yeah, I was talking about that.

Left side was popped but didn't help. Going to tow it to the mechanic and see what is what...

are you sure your getting spark?

try spraying carb cleaning into the intake and try to start the car. if it trys to run... then you have a fuel problem...... and i hope the computer is ok... jus sayin

Spark is blue. I hope it is ok as well!

On a side note I did just score a nice 1986 FSM for $5.00 plus $4.95 shipping :)

Should know more this weekend (hopefully) as what the problem is...will update it as soon as I know.

Narrowed it down - not getting fuel from the fuel pump. Tried the jumper and still nothing. Is there a fuel shutdown / reset button on this thing?

At what spot did you check that wasn't receiving fuel as it should?

The Circuit Opening Relay powers the fuel pump. It is Yellow and Black and located under the dash and just to the right of the steering column. There are five wires in the relay plug with three of them on the top row. Far left spot (Black/Red on autos otherwise B/W) has voltage w/key to start. No voltage here and the pump will not turn on. The center position wire (Black/White) has voltage w/key to on. No voltage here and the pump dies immediately after starting. In either case, the Blue wire (far right spot) will have voltage when the relay is working properly, and this Blue wire powers the pump.

Solid info - greatly appreciated. Checking this out today.

Black / Red has voltage, black / white has none.

The B/W wire should have voltage w/key to on. This wire is powered by the "15 amp Engine fuse." This fuse powers the B/W wire found at the back of the alternator and the B/W wire found in the two wire plug at the Main Relay as well.

If the Main Relay clicks w/key to on then the fuse is good. And that's the Main Relay clicking "and not" the Starter Cut Relay.

Oops - b/w is powered, b/r is not powered. had it reversed. ...with key on. Relay clicks with key on.

As originally stated, the B/R wire should have power w/key to "start" which is different than "on."

b/w is 12v at key on and b/r is at 7.5v at start. blue (double blue) is reading 0.0v at key on and about 0.25 at start.

With key to on, the reading of the Blue wire is normal. The reading w/key to start on the Blue wire is not normal as it should read basically the same voltage as the B/R wire has w/key to start. It appears the relay is faulty or the solid Black wire in the bottom row far left position of this relay, which should be a constant ground, is not grounded properly. You could jumper a ground wire to the solid Black wire in the relay plug to see if the fault lies within the wire or the relay. So jumper a ground to this bottom row far left position wire and w/key to start try taking another reading on the Blue wire.

Satch the Saint! Ground is solid, fuel pump relay is bad. Had pump running by bypassing the relay with 12v to pump for a couple os seconds and then it started for a few seconds. Thank you for all of the help. If the relay is bad i will be back...

Spoke to soon - not 100% that this car has a Fuel Pump Relay & Resistor. It is not on the wiring diagram. Best to just rewire the fuel pump?

Your car does not have that resistor relay as those are found on S4 turbos and not autos. It is your Circuit Opening Relay which is in question.

So, get a new one of these: http://lh6.googleusercontent.com/pub...p_ymZdL1CeZCSY

You stated the Black ground wire in that relay was solid. Not sure how you checked, but if you used the Black wire as the ground source for the multimeter when measuring for voltage on the top row center wire (Black/White) w/key to on and if you get the same reading as before,12 volts, then the Black ground is good thus the problem is the relay itself.

Regarding the B/W wire, I had a reading of 12v using the black wire and a reading of 12v after I grounded the black wire to the battery.

On a side note, a jumper on Yellow two prong by the passenger strut tower did absolutely nothing.

Then the relay is your problem. If you look at the diagram you provided the wire that goes to the relay at the top left of the pic shows the wire that provides voltage to the relay w/key to start and yours was about 7 to 8 volts. The Black wire at the bottom of the diagram feed the ground for the coil involved. When both these elements are present the relay closes and the voltage from the B/W wire is able to pass on to the Blue wire. You said you had a quarter of a volt when this happened.

Yes, key to start was one quarter of a volt.
Key to on was one tenth of a volt.

Is there a way to bypass this temporarily? I would imagine that a constant 12v to the pump would deliver more fuel than the engine could burn and flood. Could be wrong...idk.

The important number is the key to start. The relay requires the car to start for the AFM to supply a ground to the other coil located within the same relay. Since your car is not running you have no ground on the Brown wire and thus the relay does not close which is why the voltage off of the B/W wire does not pass onto the Blue wire so this is normal as can be, but the voltage on the Blue wire w/key to start is the problem w/the relay.

The injectors are responsible for how much fuel gets dumped into the engine and not whether the pump was constantly on or not. You could try providing constant voltage to the pump and see what happens.

I can apply a constant 12v to the pump and (with a jump start) the car will start and idle. When I put into drive it killed (with out the cables hooked up though).

That could be the battery for sure. FYI - New alternator is hooked up but the battery is probably toast, or really drained. Will make sure battery is good and retry.

The price you is never the price you pay :)

OK - sending a constant 12v to the fuel pump starts it.

Park to Reverse dies.
Park to Drive dies.
Park to Neutral runs, and then Neutral to Drive or Neutral to Reverse stays running.

When it was a 'cold' pressing the brake killed it.
Let it warm up for 2-3 minutes and pressing the brake did not kill it.

BAC needs cleaning, idle adjustment and/or weak tranny...?

Getting about 13.9v at battery right now while running.