Cranks fine, but fuel doesnt pump when the car is cranked. It does work cause we looped the test harness and fuel went, but we cant get it to go with the starter and ignition on. The car had an auto, and an alarm, and some weird relay stuff under the dash on the fuel relay harness or something. Any ideas? thank u

John

 

Yeah. The wiring is connected up wrong because the car was a automatic at one time. When you hold the key to Start, you send batt voltage to the starter solenoid and also the circuit opening relay. It's either a black/white wire or a black/red wire that splices off the starter solenoid wire and goes to the circuit opening relay.

I attached two jpg. You'll have to figure out how and where the missing wire is.

 

Not only is the START signal supposed to go to the starter solenoid and the circuit opening relay, but it is also supposed to go to the ECU. Pin 3B I believe.

This signal to 3B, lets the ECU know that the engine is being started. Sort of a heads up to the ECU. That is done so the ECU will use an internal fuel map for the Start cycle in lieu of using the afm signal for fuel during start.

The wire that goes to the circuit opening relay and the pin 3B is after the Starter Cut Relay, according to the second jpg I attached, and seems to have something to do with the automatics INHIBITOR SWITCH, which I ASSume was on the automatic transmission, which ain't thar no mo.

Look under the car for a plug that is configured like the plug labled E-14. That's what I'd do. Should have a B/R and a B/W wire going to it.

It's too confusing to me. Plug should be down there somewhere.


By the way, the Circuit Opening Relay has two coils to pull it in. One is operated by the afm and check connector, the other by that signal from the start signal coming off the start circuit.

 

i'm not sure man, i know nothing about electrics, my buddy does though, hes coming over today or tomorrow, is there like, a laymans way to explain it?

 

The start circuit went thru a inhibitor switch when this car was an automatic.

Someone put a standard five speed in the car. It has no inhibitor switch.

Whoever did this conversion did some sort of workaround of the inhibitor switch, and when he did that, he ignored the importance of the wire in that circuit that sends 12vdc to the Circuit Opening Relay (operates the fuel pump).

Simply put, the starter is working now, but you need to splice that wire that goes to the circuit opening relay, TO the wire going to the starter solenoid.

I assume the circuit opening relay is not pulling in when you go to Start, because YOU implied that.

I'd prove it. Pull the small plug off the ECU. Pin 3B has a black/blue wire in it. Put the meter on dc volts and then put the key to Start. Approx 6-12vdc should show up on 3B IF things were done right. IF no voltage shows up, tough. Gotta find the wire that goes to the ECU and circuit opening relay, and splice it to the wire going to the starter solenoid.

According to the second jpg I attached, the color of the wire would be Black/Red

 

well, i've tried a few things with the wiring, I'm not sure which wires to connect where...

cause i dont have the wiring diagram near the fuel pump relay, and like, theres cut wires, and and an additional relay that used to be around the cut ones, they spliced into the blue ones iirc from the fuel pump relay, and like, i found the "inhibitor switch relay" from the ecu 3D cause i thought thats what i connect to the starter wire on the igntiontion the black and red...., is it the 3B that i connect to that one? lmk please i think i can get this figured out today, also the O2 connector i cant find it in the bay, its the S4... thank you for the advice

John

 

The non turbo series four has a Circuit Opening Relay. IT has nothing called a Fuel Pump Relay, even though the circuit opening relay performs that function plus some. I won't ever use the term fuel relay because it just causes CONFUSION if you look at the wiring diagrams for a non turbo car and are looking for something called *fuel relay*, it ain't a gonna ever, never be found. It just wastes time and effort to call it that.

The ECU does not in any form or fashion Control the Circuit Opening relay nor any part of powering the starter or fuel pump. The pin 3B is a INPUT from the start circuit, not an output from the ECU.

3B is on the small plug of the ECU and is Black with Blue stripe. Jpg attached.

I've never seen an automatic, but it seems the wire off the starter circuit is Black/Red and god only knows where that wire is on the starter circuit.

The Circuit Opening Relay sounds so honked up there's no way this person could figure it out from here (why the circuit opening relay is not getting pwr when the key is put to Start).

One of the jpgs attached shows the Circuit Opening Relay and what the plug looks like and what the wire colors to the coil look like. IF you car was a auto, then the circuit opening relay should have a B/R wire in its plug just like the picture. THAT B/R comes off the start circuit. All one has to do is find the small wire that goes to the starter solenoid. Then splice into that wire and run that wire to the Circuit Opening Relay where the B/R wire is shown in the jpg attached. Walla, if the ground for that coil is going to gnd, then it'll pull in each time you go to Start and hold the key to START.

All the wiring diagrams for a series four are online and can be downloaded. They show all wiring for the car except internal items of things like the wiper motor, ECU internals etc.

 

well, i hooked that brown wired from the relay to like, a few of the other ones, i got the fuel pump to make noise on start and cranking, but still no fuel to the housings, i think what happened is the engine harness up under the intake manifold in the rats nest, i cut it to do the swap, and i rewired it, and i may have connected some of the to the wrong place, so i'm gonna have to do and rewire that entire cluster of wires, would that cause fuel to not reach the housings when cranking? or does it still sound like a relay issue, i'm new to rx-7's so idk what its supposed to sound like, the fuel pump and everything is the relay supposd to hum the entire time? and the fuel pump make the humming noise...