A bit of a strange one here. A few days ago I changed my spark plug leads to some RE Ameniya ones as my current ones have been on almost 19 years I think and their resistance was way higher than what they should be. Anyway, I turn the key and the engine fires for a second and then dies. I think it's flooded so check the wiring and pull the plugs but no fuel and all seems well. But it still won't fire.

I did some troubleshooting and found that my 15A engine fuse was blown. So I replaced it and rechecked the plug wires to make sure they were fully connected but it blew straight away, even with the key just put to the "on" position (not even starting). I started to wonder if it was some of the wiring in my fuel pump rewire modification that I'd done so I pulled the 15A fuse going from the battery to my new fuel pump relay to check, but as soon as the key goes to the "on" position the 15A engine fuse will keep blowing.

Have no idea what I could have done that would cause this fuse to suddenly keep blowing; could I have knocked something near the ignition coils when I was replacing the leads? Any thoughts on the problem and how to solve it would be greatly appreciated

Should note I have also tried changing back to the original leads and I still have the same problem.

 

T'ain't the new spark plug wires, you must have dislodged something hot while changing them out.

 

The ENGINE fuse feeds the coil of the MAIN RELAY.................the coil of the CIRCUIT OPENING RELAY.............the fuel pump via the CIRCUIT OPENING RELAYs internal contacts........and the black/white wire on the small plug of the alternator.

That's series four. Series five similar. See your local wiring diagram.

 

OK, well I'm thinking I've taken the fuel pump out of the system. I pulled the fuse I've got about 6" from the battery and then which goes to the fuel pump after my rewire (which has worked fine for over a month), and it was still blowing fuses. Hmmm... the plug on the alternator might be worth checking.

HAILERS - I've seen your comments on checking the main and circuit opening relays before. These are under the steering wheel, right? What colour are they? Just want to make sure I'm pulling off the right bits.

EDIT: I also pulled my battery out to charge it. Wonder if I knocked something out doing that.

 

Post #166 in link below, first pic, depicts the Circuit Opening Relay.

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/86-tii-swap-wont-start-but-really-wants-887302/page7/


Main relay is fastened to the fender and located between your trailing coil and the fire wall. It will have two plugs, one with 4 wires and the other with 2 wires. Engine fuse connects to the 2 wire plug. Disconnect this plug.

 

Near the coil and fire wall? Hmmm... definitely worth checking that I think then. Will buy a whole bunch of 15A fuses to replace the ones I kept throwing in there today and for troubleshooting. Will report back tomorrow night with my findings.

Cheers for your help so far

 

As HAILERS has mentioned before, if I remember correctly, if your car "is/was" an automatic then there would be a 4th possible issue.

 

Isn't and wasn't ever an automatic so hopefully this 4th issue won't apply.

 

OK, progress report time.

Pulled the 2-wire plug out of the main relay and turned ignition on - fuse blows
Pulled the connector out of circuit opening relay and turned ignition on, fuse doesn't blow. Turn key and engine almost fires but then dies.

Tested circuit opening relay and all the voltages & resistances came back ok. I then look at what the circuit opening relay does again, and go to the back to check my fuel pump relay I rigged up. One wire (blue and something) was loose so I reconnected it and put the connector back onto circuit opening relay. When ignition goes to "on" it's fine, but when it goes to "Start" it blows again. Then tried putting ignition to "on" and then connecting the fuel pump diagnostic switch (the yellow one in the engine bay). Sure enough, as soon as I connected it, the fuse blew.

So it looks like my fabulous mechanical skills have failed somewhere again. Am going to have to check and probably redo all the wiring going to the pump and maybe get a new relay too

 

The circuit opening relay is probably just fine.

No power goes to the fuel pump on a series four car unless the key is HELD to START or if the fuel pump check connector is jumpered. Jumpering that connector does the same as HOLDING the key to START...............both acts pull in the circuit opening relay which in turn passes power on to the fuel pump.

Meaning that the wiring to the fuel pump is suspect.

 

Yeah, it does look that way. Damn I hate wiring (and most of the time it hates me too).

OK, with the pump I've got a wire from the battery that's connected to the relay and that's got a 15A fuse on it. If that wire is shorting out anywhere, surely it would blow the inline fuse, right? So it could be the wire that goes from the circuit opening relay to pin 85 on the relay, seeing as it's causing the 15A engine fuse to blow?

Am just trying to work out my best strategy for tackling this thing as I'm not so sure what I should be testing. I've got a new relay in there with the fuel pump resistor eliminated, and just to reiterate it has been working fine for over a month.

 

Turbo or non turbo car?

Either car the wire color is BLUE in the rear harness plug that connects to the fuel pump check connector. The blue wire is a bit larger than the other wires in that plug. I'd disconnect that blue wire from your relay and then see if the fuse blows or not.

IF someone has installed a fuel cut switch at the circuit opening relay .........that might be suspect also.

Turbo cars have the OTHER relay called the fuel pump resistor relay located up front in the car near the right headlight. The circuit opening relay passes power to it before that fuel pump resistor relay finally passes the power on to the fuel pump plug in the rear of the car.

 

1991 S5 turbo. Japanese car with full fuel pump rewire (relay inserter & resistor relay eliminated).

No fuel cut off switch currently; just the rewire.

 

Well on a series five the wire that feeds power is BLUE/GREEN instead of the pure blue on a series four. So disconnect that blue/green from your relay and see what happens.

 

Once again, you've helped me out

Pulled the blue wire and blew a fuse again when I turned the key, but mentioning the resistor relay at the front got me thinking. Pulled the air filter out of the way and found some of the insulation tape I had on one of the soldered connections had come off, and typically it was resting on a grounding point. Insulated it again, reconnected the blue wire and turned the key. Engine fire up first time.