I've bought an '87 TurboII with a blow rear rotor. It would run (kind of) on one rotor. I got a J-spec engine with good compression and installed it. It will not inject fuel.
The car is an early '87 so it had low impedance injectors fro the factory. Come to find out the bad engine that was in it was a J-spec engine with high impedance injectors (offset tab on plug), but the resister pack was not jumpered for the high impedance injectors. I jumpered the resister pack for the high impedance injectors in the new J-spec engine and it will not inject fuel. It will run when I squirt in starting fluid/gas, but stops when it runs out. I even tried going back to the resister pack, but nothing. I'm getting 12 volts to the black wire that goes to the resister plug and 12 volts to the fuse at the main block.
Anyone have this problem before?

 

Sounds more like a fuel pump problem to me. Tried jumpering the pump to see if its running?

 

make sure the fuel lines are right too. they are backwards on the j-specs...

 

pump is putting out fuel. Good pressure.

 

Fuel lines are right. 12 volts to resistor pack, 12 volts to fuse. High impedance injectors

 

Double check the fuel lines. As Scott said, they're arranged opposite on J-specs (i.e. supply to secondary rail, return to primary rail. This is a common J-spec swap mistake.

 

Your description seems confusing. Let me go over how each system SHOULD work, then you can troubleshoot whatever you have rigged up there on your own.

LOW IMPEDANCE:

The main relay sends 12vdc+ to the injector resistor pack. Here, the single 12vdc+ wire is split into 4, each of which is run through a resistor. OUtput of the pack is 4x12vdc+ @ 6-10ohms. From here, each of thse 4 wires carries power to one side of each injector plug. This is a constant power supply. The injectors are triggered by ground, which comes directly from the ecu. There are 4 ecu injector outputs, each of which goes straight to the other side of the injector plug, and combined with the constant 12vdc+ leads, triggers injectors. The injectors are 2.5-3.5 ohm, the pack is 6-10ohm, and the ecu sees about 12-14 ohm load.

HIGH IMPEDANCE:

Same as above, but there is no resistor pack. The single constant 12vdc+ wire is split in the harness and supplies constant, non-resisted power to each injector plug. Again, the ecu triggers ground via 4 independent wires. Injectors are 12-14ohm each, with no resistors, and the ecu sees that same load.

IF you don't get injector pulse, find out whether you are missing the constant + or the ground trigger pulse. Most likely it will be the constant +, a wiring or fuse issue found easily enough. Lack of ground trigger indicates a problem in the ecu or CAS, or grounding of the engine/ecu.

 

I've got 12vdc+ at the one black wire at the resistor pack. I've jumpered that one wire to the 4 brown injector wires. I have the fuel feed line (the one that has the fuel filter on it) connected to the fuel line that has the pressure regulator (I also tried this both ways just to make sure.) I've checked all the fuses at the main fuse buss in the left side of the engine compartment with a fluke meter for continuity. Is there any check I can do at the computer in the passenger side of the car? It worked fine when I had the old j-spec in the car just before installing the new one. The old j-spec had high impedance injectors, but worked with the resistor pack, is this possible? All injectors on both engine have offset notch on outside of injector and are a redish color.

 

The FPR is always the LAST component in your fuel system, before the fuel gets returned (low pressure) to the tank. I think you have your lines backwards.

Secondly, you didn't say you checked for injector pulse on the primaries, nor did you say you checked for 12vdc+ on one side of each injector plug, and ground trigger on the other side of each primary plug when the key is on and the CAS/engine spun (I use a spare CAS for this, without even turning the engine). IF we're going to help you, you're going to need to follow instructions.

Your rig with the injectors doesnt sound right. IT shouldnt keep the car from running, but I wouldnt leave it like that. Remove the injector plug, and check impedance of all 4 injectors, just to be sure. IF they are 12+ ohms, then remove the injector resistor pack. Jumper each of the 4 terminals to the center wire, completing the circuit and bypassing the pack altogether, this will be the same as a stock high impedance harness.

Also see www.rotaryresurrection.com in the tech section for injector info.

 

Wait a minute.....
Ok so NZ says Jspec fuel goes to the secondary rail first.

and Kevin says the FPR is always last.....

My S5 Jspec has the FPR on the secondary rail.....

So I am going to believe Kevin just because that sounds logical to me.

Care to explain why a Jspec fuel system would be switched?

 

HEre is how a fuel system works. A pump alone generates some pressure, and volume. However, it can't biuld full pressure without a restriction somewhere, which is the pressure regulator. Since you want the injectors to get this high pressure, you put the FPR after the injectors. The FPR acts as a one way valve, building pressure between it and the pump, at times letting more fuel out than others (variable fuel pressure dependent on load). So, the FPR helps form a high pressure side and a low pressure side...whatever the FPR vents out, goes through the return line into the tank.

So, switched fuel lines will lead to little or no fuel getting to the injectors...the FPR acts as a one way valve.

 

Yeah I understand that.

I'm just curious as to why a Jspec engine would have it opposite? or why people believe this?

It doesn't make sense to me for Mazda to completey reverse the fuel components because that would mean the FPR would have to go on the Primary rail which has Very little room under the UIM and the costs alone sound illogical.

My S5 Jspec has the fuel setup of a US Spec or atleast that's what it looks like.

 

The FPR is always the last thing before the excess fuel gets dumped back in the tank. Jpg supplied. Make your car look like this:

 

I've bypassed the resistor pack and jumpered the 4 brown leads to the center black 12vdc wire. I've also tried putting it back th way it was.
The injectors are a reddish color(purple before years of heat) and have the offset tab on the outside of the square plug=high impedance.
I'm just going now to check the injector pulse on the primary injectors, and by "ground trigger' I'm assuming that is on the computer side of the injector wiring (negative.) CAS is a ?
What I'm wondering is that the j-spec engine I took out had the red/purple high impedance injectors but it ran, how is this possible. Can the high impedance injectors open with less voltage?

 

ok...I have this same problem on my J-Spec, except mine is a little wierder. The car was running perfectly on thursday night. Parked it about 3am, got up at 10am and installed a 3rd gen fuel pump. Now it wont start, I thought i flooded it, did the procedures for that, and still nothing. Reinstalled the stock one, made sure it was working, still nothing, plugs firing, It will run when I squirt in starting fluid/gas, but stops when it runs out. All I can think of is that injectors arent firing....

 

We are both correct.
Then it hasn't got J-spec fuel rails.
I have no idea, you'll have to ask Mazda. But they are opposite.
I believe it because I've seen it on my own engine, on friends' engines, and in pics of J-spec engines on this forum.
Another Mazda mystery. There's plenty of room under the UIM for the FPR. It's the same size as the PD remember.

 

agree with jason here, the jspecs have opp fuel lines from a- spec, but on my re motor the fuel lines were feed on lower and return on secondary rail.

 

bump^

 

Well my Jspec has proven to be an abnormal S5 engine.

Like I posted in another thread by UIM has no mounting holes for a ASV for the PS and the Intercooler has no extra holes in it for what ever that nipple does on A Specs.

The Fuel rails also has the PD on the primary and FPR on the Secondary.

 

****The Fuel rails also has the PD on the primary and FPR on the Secondary****

Both my series four have that arrangement. For what it's worth. I consider that normal for a series four USA

 

It certainly has. Where did you get it from? Is it fresh off the boat or has it been previously modded in the US?

 

I can say that I have never worked on a jspec that has the FPR and FPD swapped. Wouldnt this also mean there would be a different jspec vacuum rack? This doesnt make sense...

 

I'm surprised you've never seen this. I've never heard of a J-spec that didn't have them it opposite locations to US-spec engines. It almost sounds like you still don't believe...

I stated in several threads that it doesn't seem to make much sense, but I guess Mazda had their reasons. And yes, a different vac rack would be required.

 

I dont really care one way or another, as far as believing. I just said that I had not yet seen this setup. I dont deal with a lot of jspec stuff, though, perhaps that is why. I have worked on 4 or 5 supposed jspec swap engines, and none had this.

 

This engine was a Core Jspec from the west coast.

I have no idea on what car it came from. The intercooler did have japanese writing on it though.

Kevin. This was the engine you rebuilt for me. It was the one with the rusted/bad front rotor.

I've already hacked the vac rack so I can't takle pics for you.