Hello all, thanks for reading.

I have an 88 RX7 SE that I acquired recently. It suffered a (small) engine fire which melted some of the wiring. I've replaced the entire wiring harness, but the car is still not getting fuel - the rotors are bone dry.

The Facts:
1) I have spark/compression: I dumped some fuel down the intake and it fires readily off that - so the electrical system is ok.
2) I have verified that the new wiring harness is installed correctly.
3) Swapped out computers for a different one - no change.
4) Checked & Cleaned all ground wires.
5) I have fuel pressure and have put fresh fuel in the tank.

Questions:
I have noticed that this "Shift Up" light is always on when I have the car at start or run. Is this normal?

I've also read that the 88's have a feature that, on startup, if the gas pedal is to the floor, it will cut off fuel to the car. Can anyone verify if either of these two things is normal/true? I tried disconnecting the Throttle Position Sensor to no avail.

My thought here is that if the car 'thought' it was at full throttle, then it might be cutting off its own gas.

I am considering getting a replacement set of injectors - how can I tell which ones I need? Low impedeance vs High impedeance?

Thanks for helping out a nuub - this'll be a fun car if I can get it working correctly.
-retrofime

 

Your taking a bad approach. Get a digital meter and find the ECU. See if there is battery voltage at each injector wire with the key to ON.

Have a factory service manual handy or downloaded from the free internet site with the wiring schematics.

With the key to ON and the fuel pump check connector installed, Pull off the fuel RETURN line on the left side of the engine and see if fuel pours out. Be careful. OR just install the fuel pump check connector and listen for the fuel running thru the rails and back to the tank. Listen at the filler cap if needed. If you hear it sloshing then you know thats not a problem.

1986 are all low impedence.

The gas pedal to the floor only applies to series five RX-7....ain't your car.

 

A slightly better idea. Since it's a series four non turbo you can take off your secondary injectors plugs. Do so and see if one wire on each plug has 12vdc with the key to ON. That might give you a clue. It won't verify the primarys are right but....will give you a clue.

By the way, is your injectors resistor package connected up???? Sorry, brain fade right now. Its a package of resistors located about a half foot below the air filter and held on the fender with two bolts. It has a aluminium cover on it. IT must be plugged in.

The solenoid resistor package looks like this: http://www.teamfc3s.org/forum/showth...threadid=33353

Let's say the package is connected up but the secondary do not have 12vdc. Then pull the plug off the package and see if there is 12vdc on the Black/Yellow wire in the harness plug. No 12vdc equals no injector voltage. See if the EGI INJ fuse is good or not.

 

Hi Hailers, thanks for the replies.

I took the intake manifold off tonight and to test some things. Since I still have it taken apart, I'll check all 4 injector wires for voltage Tuesday.

I did take a quick look for that resistor box you mentioned, but I could not find it.

I am certain I am getting fuel to the injectors - I have taken this system apart more than once now, and cleared fuel from the fuel rails each time (and it was under decent pressure)

I did some testing on the injectors themselves - when I apply a 12vdc charge, the injector does open.

I'll check the 12v lines tomorrow with my trusty multi meter.

Thanks for the ideas, I'll let ya know what I find.
-retrofitme

 

if its a real 88, it doesnt have the resistor box! and the injectors are high impedeance with the square plug on top, not sure the exact part number its in the FAQ somewhere i belive....

 

My bad. I for some reason saw 86 instead of 88. Forget the solenoid resistor.

 

Well I checked for voltage, and I get nothing. I tested only the secondary injectors with the key on the ON position.

I checked the fuses and all looked ok. I even swapped out a couple to test and still nothing.

Any more thoughts?

 

If nothing works, try and check your fuel filter. If it's not changed after a really long time, it could be clogged. If not, look at the fuel system components including the fuel pressure regulator and fuel pump components.
Also, try and look at your fuel injectors. If it's leaking, your engine may be flooded. With the injectors leaking, overtime it accumulates fuels which floods the engine. When you give it ignition, the combustion is offset because there is too much fuel and not enough air for the chamber. Try a fuel cut off trick. Underneath the dash where the pedals are on the drivers side there should be a yellow plug (check the manual for the exact plug location; electrical) and unplug it. This ensures no fuel feeding the injectors at all at start up. Start the engine and when it starts, connect the plug back to continue flow of the fuel pump. If this works, you have leaking injectors, and you need to replace it with OEM parts from your Mazda dealer or parts warehouse. If you have the money just save some time and just replace the primary and secondary injectors to ensure that they are brand new and fully opperational.
If this don't work, well....i'm out of ideas!

 

Odd no power to the fuel injector plugs whether primary or secondary. With the meter on a good ground and the key to ON the Brown/Yellow wire on the rear secondary and the Brown/White wire on the front secondary should have shown 12vdc.

So let's say it does not. Well, the voltage comes from the MAIN RELAY and it passes thru only one connector besides the one at the main relay before getting to the injector plugs. That plug is located above the passengers feet and to the far right of the foot well. It's a dark yellow plug and hard to reach. It will have a Black/Yellow wire in it that comes from the Main Relay. So you'd check that one.

But this makes no sense. That same (Black/Yellow) wire feeds the coil assy's and you have spark, so you KNOW the fuses are good and the Main Relay is good. I'd double check the wires at the secondary injector plugs. Maybe you had the key off when you checked? Use the engine or the battery neg termainal for the meters ground when you do this. DO NOT use the other socket of the two in the injector plug.

 

Ah! Replaced the entire wiring harness did you. Maybe you didn't get that connector on good I talked about above. It's dark yellow and has 13 sockets/pins. Look for two Black/Yellow wires in the plug, one above the other. They each should have 12vdc with the key to ON. That would be the half of the plug on the FRONT harness. You just replaced the EMISSIONS harness half of the plug when you changed harnesses.

Another thought is that someone sold you a turbo harness or a early 86-87 harness. They would need the Solenoid Resistor I talked about in the beginning. It that were the case, then you would find on that below the air filter, on the new harness, would be a very large round plug with nothing connected to it.

 

Well, here is the latest.

I pulled the entire intake manifold off (again) and removed the primary injectors and tested them with the car. They have fuel in the rail, but not a drop comes out when turning the car over. So I feel I have eliminated any sort of fuel problem.

Next, I am going to put my meter on the injector wire itself and attempt to turn the car over - to see if I am getting any voltage. If I find I am not getting voltage to the injector wires, what could be the cause of my issue?

Thanks again for all your help - this forum is exceedinly helpful and I appreciate it.

 

No. When you turn the key to ON or better, you put 12vdc on one wire at each injector.

The other wire recieves a momentary ground signal from the ECU. That causes the injector to spit fuel.

You said you have spark. The same wire the supplies voltage to the coils supplies voltage to one wire on each injector.

The cas when turning, sends the signal to the ECU as to where the rotor is at a given time and the ECU then causes the coil to spark and also causes the injectors to inject when they are supposed to by putting a momentary ground signal on the injectors.

If you have spark then you know the cas wires are good b/t the CAS and the ECU.

You check for voltage at each injector plug by putting the meters negative lead on a known ground such as the battery negative post or the engine housings and the positive lead on the injector plug socket. Which wire on the injector? Colors are in the fsm but as long as ONE on each injector plug has 12vdc that is good. The plug does not care which socket the voltage is on.

The voltage for the injectors comes from the EGI INJECTOR fuse (which you know is good already), to the Main Relay (which you know is good already) to plug X-16 on a 87 series four (called FEM-02 on a 88) then to the fuel injector and from there to the pins 3C, 3E, 3F, 3H where at the right time the ECU will put a gound on them in turn momentarily.

No voltage with the key to ON? Then I suggest you find the connector called either FEM-02 or X-16 and pull it apart. Fing the Black/Yellow wires (see the S in wires????) and see if you have 12vdc on them when the key is to ON or better. You would look at the FRONT harness part of that plug. The other half is the emissions harness part of that plug.

I also worry someone sold you a 86-87 1/2 emissions harness that requires a solenoid resistor to work. A large plug would now be disconnected under the afm if that was so.

If you tire of me answering this thread constantly, then start another thread and I'll stop answering and let others pipe in IF they have better ideas.

HECK, I wouldn't pull the manifold off to check voltage for the injectors. I'd pull the small plug off the ECU and with the key to ON see if there was 12vdc at each of the pins I denoted earlier. 3E, 3F, 3C, 3H. Schematics/pictures of the ecu PLUGS are in the fsm in the Contro Unit pages. Or the wiring schematics. P.S. the injectors have to have their plugs on to do the check at the ECU.

I know the first thing I would have done if I knew I had spark, would be to go to those pins on the ECU. If no voltage there I'd disconnect the FEM-02 and check the voltage on the black/yellow wires on the FRONT HARNESS.

EMISSIONS HARNESS........the harness with the fuel injectors.

FRONT HARNESS..........the one the emissions harness connects to in the foot well (not the ECU plugs but those two large dark yellow ones).

 

Hi Hailers - I want to assure you that I greatly appreciate your replies. You're the only one who has taken notice of my thread and I value your opinion. I feel there is a great deal about this car I can learn from you. I think you may be correct that the wiring harness I got from ebay was not from an 88 (though I verified twice with the seller before purchasing that this was the case (grrrr). I do have an extra connector right where you say it should be, it is oval shaped, white connector with 4 or 5 connectors (I don't have it in front of me right now). If this is the case, can I use this harness, or am I SOL?

I didn't realize that it was a ground-activated system for the injectors - that's good to know.

I'll read through the ECU pinouts diagrams I have and test from there.

Thanks again, I'll let you know how it goes.
-retrofitme

 

Ah! Your in luck. There will be no real problem. That plug has ONE wire that should be black/yellow and it is the HOT one with 12vdc witht the key to ON.

What you have to do is splice ALL FIVE wires together by hook or crook. Your method, your choice.

You could just cut the plug off and strip the ends of all the wires and splice them together/solder them together/crimp them all together and then cover them with some shrink tubing or some kind of wrap to keep them from shorting out if they touch ground.

Once you do that the car should start right up.

Or you could try to come by a Solenoid Resistor Package off a early model RX and use that. Pesonally I'd just get it over with and do a good splice 'em all together job and start the car up.

Don't get jumpy about joining all five together. It's one hot wire that will be now feeding the other four. The other four go directly to the fuel injectors.

With a little luck the CLOWN did not sell you a turbo harness. I assume yours is a non turbo (frankly I know squat about models of RX-7). One way to tell right away is to turn the key to ON and look at the idiot lights. If all the lights light up then you have a non turbo. That is IF the alternator wires are connected up to the alternator. If the lights don't come on, errrrrrrrrrrrrr , could be a turbo harness, maybe.

And the plug you described is the one for a Solenoid Resistor Package.

 

Hey I checked that line and it is showing 12+ on that wire. I can splice that stuff together - I've got everything I need there. I don't have time to work on it tonight, but I am sure I will get a chance to work on it tomorrow.

My car is definately a non-turbo. I wish it was. Maybe someday!

I'll let ya know how it goes.

Thanks again!
-retrofime

 

Start simple. First, check to see if your fuel pump is getting 12v, you got to open the tank... multimeter the lines with the ignition on, not started, work your way down the circuit, then the fuse... THEN check the fuel filter, then the regulator, <i>then</i> your fuel injectors, if you know for sure its them.

 

You seem to have missed the boat, KamakazieX. His problem was CLOWN sold him a early 86/87 harness that requires a Solenoid Resistor Package (his car is a 88), , hence no injector action due to the lack of 12vdc at the injector plugs.

Splicing the five wires at the solenoid resistor plug WILL result in injector action and he already had spark and fuel in the rails. The car WILL now start.

 

Well I did a test with those five wires linked together and still nothing. I literally have the injectors out of the rotor housings so I can watch and they don't open/spray fuel.

If he did sell me a turbo harness, how would I know?

Thanks,
-retrofitme

 

Even with a turbo harness it should have started.

I need confirmation. With the five wires spliced together, and the key to ON, if you take an injector plug off, do you have 12vdc on one of the two sockets?

A good indication of turbo vs a non turbo is when you turn the key just to ON, do the idiot lights all light up? This is with the alternator plug installed on the alternator. IF the idiot lights were working before you did you harness change, then they should all light up now EXCEPT if you have a turbo harness in its place.

Another key is that the turbo emissions harness won't have a plug for the alternator, unlike your non turbo.

If each of the injector plugs has 12v on one of their sockets, then visit the ECU and its small plug. With the key to ON, check for 12v at each injector wire. Plug on or off the ECU matters not. Your checking the socket on the small plug, NOT the ECU samll jack.

Another thing. The grounds for the circuitry of the ECU are located on the TOP OF THE REAR ROTOR HOUSING. Two black wires in a ring terminal bolted to a *boss* on the REAR ROTOR housing. They MUST be bolted down.

EDIT: You know there is no fuel pressure in the rail unless the fuel pump check connector is jumpered and the key is to ON or the key is held to START.

If you have 12v at each of the injector wires and the ring terminal is on the REAR ROTOR HOUSING then the ECU is suspect.

Remember something about your harness. When you installed it you had two plugs going to the ECU and two other plugs up higher colored dark yellow. Those last two must be also connected up. Recheck them.

 

One more thought. You said you had 12v at one of the five wires at the solenoid resistor plug before you spliced them together. Is it possible that you shorted that wire sometime while doing the splice and blew the fuse????/ EGI INJECTOR FUSE in the engine compartment. Maybe check the ENGINE fuse in the interior fuse box also.

 

ok, here is the latest:

I need confirmation. With the five wires spliced together, and the key to ON, if you take an injector plug off, do you have 12vdc on one of the two sockets?

No, my volt meter only shows 0.20v on one line, and nothing on the other for each plug. This is true for all four injector wires, primaries and secondaries. I tested my meter on the battery with the same ground and I get 12v no problem.

One more thought. You said you had 12v at one of the five wires at the solenoid resistor plug before you spliced them together. Is it possible that you shorted that wire sometime while doing the splice and blew the fuse????/ EGI INJECTOR FUSE in the engine compartment. Maybe check the ENGINE fuse in the interior fuse box also.

When I first went out to the garage tonight, I reverified that I have 12v coming through the resistor connector - I also rechecked the fuses and they still look good. I havent actually spliced anything yet - I just took some spare wire an insterted it into the plugs so that it was making contact. However, I think I may have accidentally grounded out the connector - now all I get is 0.20v from that line too. Does the fuse box in driver's side footwell control any of the engine components?

Another thing. The grounds for the circuitry of the ECU are located on the TOP OF THE REAR ROTOR HOUSING. Two black wires in a ring terminal bolted to a *boss* on the REAR ROTOR housing. They MUST be bolted down.

Tonight I replaced both ground wires with new wires. I used new connectors, and used my dremel's wire wheel to clean all the contact points. Unless there is a ground wire I haven't found, my grounding should be good.

Thanks again for your help...I don't suppose you are planning any trips to Minnesota any time soon?

-retrofitme

 

Oh. The 12v at the solenoid resistor comes from the Main Relay. The Main Relay should be fed from the 40 amp EGI INJ fuse in the engine fuse box. That fuse also feeds the coil assy's. Black/Yellow wire.

I'll also jpg a picutre of the solenoid resistor plug. It sounds like you have the right plug. Some what oval in shape and five wires. Fairly large plug compared to others.

You must have shorted something. I KNOW if you put all five together you don't short anything, just feed 12v on each individual wire to each injector.

The only fuse in the interior that could cause a problem would be the one labled ENGINE fuse.

 

Here's a couple of jpg of the solenoid resistor. You'll see the half of the plug you DO NOT have. It has five pins in it. DO NOT pay any attention to any words on the jps. They were directed at someone else long ago.

 

These two jpg show the circuit. You have to put both jpg together to make the picture. Follow the BY wire from the Main Relay to the solenoid resistor.

You might check and make sure the ENGINE fuse is good. It pulls in the Main Relay when the key is to ON.

 

Hi Hailers - that is the plug I jumped together. I had voltage on that plug until I accidentally grounded it out, now it shows only 0.20v I'll check the fuses again, and I'll check the fuse box in the car and let ya know.