Working S5 motor and harness into S4 chassis.

Finished everything, now it wont start. I can't seem to find the fuel pump relay, its missing, so i just hard wired the fuel pump to the battery. next i checked for spark, spark is fine. then i made sure there was fuel pressure. all i did, was take the fuel return line off of the fuel pump, hooked it up for a moment, and fuel flowed from the engine towards the fuel pump like it should.

With a trailing 1 spark plug removed i hooked up the fuel pump, waited 10 seconds for priming. then attempted to start, I dont believe any fuel is coming out of the spark plug hole.

My first question is if the fuel pump relay is in some way connected to the injectors working, i cant see it in the wiring diagrams or see a reason for it to. But i'm unsure, anyone know for sure if it will run without the relay?

And if it will run with out it, any specific reasons as to why the injectors arent firing, the car run before i took the motor out.

Thanks

 

The pump relay is under the dash, i know that at least.

Check to see if youre getting 12v (but not a ground) from the injector connectors when the ignition is on. Also, are you using the right impedance injectors for your wiring harness?

 

Not according to the FSM

Bottom right turbo II picture shows it up front.




I found the plug, for me its in with the left side headlight harness, but mine is backward because i'm using a complete RHD harness.

The harness, injectors, ECU are all the same as it was before. Only think changed is the fuel pump....and a missing fuel pump relay.

the circuit opening relay is under the dash, are you think if that one?

 

I just checked grounds and such.all major engine compartment grounds are in place and tight. There is a bunch missing in the dash and rear because for the most part there is nothing there.

None of the cluster or instruments are in place and are not connected. But i dont see how that would cause the injectors to not fire.

The ECU engineground is in place, just under the TB at the transmission. the ECU ground is connected to the ECU holder. The main battery ground is connected to the frame rail/strut tower. Plus ramdom grounds around the engine bay.

What would keep the injectors from working? fuel pump relay have anything to do with it?

 

There is and never has been a PRIME for the fuel pump. Period.

Next time, remove the RETURN line for the fuel pump and then turn the fuel pump on. Your favorite method of jumpering the pump will do. If fuel flows out the RETURN line FROM the engine, then it isn't a fuel problem.

Look for battery voltage at the fuel injector wires on the ECU PLUG. Plug disconnected from the ECU. No batt voltage means there's SOMETHING not connected up.

 

Did you check for 12V at the injectors?

 

the relay is under the dash closest to your break . its actualy behind it. its common to modd off of that relay and make a fuel cut off switch.
if your going from s5 engine to s4 chassy harness. that very well may be your issue.....

 

well is that s4 or s5?

 

Like the man said, look for 12v at the ECU PLUG for each injector. No 12v.......sometning isn't connected up right.

There is and never has been a PRIME for the fuel pump. Period.

Next time you jumper the fuel pump, look for fuel coming out the RETURN line, not the pressure line. IF no fuel is being returned.........the fuel lines are crossed at the engine.

There is NO fuel pump resistor relay package on a series four non turbo. Only the Circuit Opening Relay.

 

Manual says to prime it. so i did. Cars usually tend to, you know, turn the car to on, and you can hear the fuel pump hum for a couple of seconds.

I did remove the fuel return line at the fuel pump, and that is what happen...did i not explain that above??!?

I'll try that ECU plug, the voltage is constant correct? ECU controls via the ground?



No, I like the way above better, I'd perfer to not take off the upper intake manifold.




Nearly everything is Jspec S5 TII. pretty much only the stuff that has to be changed is, for instance, wiper motor, hear core, ignition swtich.

All harnesses are S5. the diagram is for S5.

 

I'm not jumpering, it wouldnt do anything, the fuel pump relay is missing, like i cant find it, with the fuel pump plugged in, it wont turn on, so i bypassed it and just hard wired it.

lol I already said fuel is being returned. So that is fine.

You last sentance interest me. Ok, so no fuel pump relay. S5 Tii, is there a resistor in the relay that is required my the injectors to work correctly?

 

No resistor in play.

If I remember, you said pressure came out from the pump. That is not the same as returning from the engine. If the fuel lines are crossed, fuel pressure may be at the engine, but it won't return. The fuel should be constantly returning to the tank if the pump is ON.

Early 87 had a SOLENOID RESISTOR in line with the fuel injector power wire. Located below the afm and bolted to the fender. Large plug with five wires. One wire power, the other four coming out of 6.0 ohm resistors inside and going to the injectors and then to the ECU. That's why it's been repeated to check for 12v AT the PLUG on the ECU. Remove the plug and check for 12v at each injector wire. No power.........no injection.

 

No, fuel goes all the way around. and shoots out of the hose and would be going back into the fuel tank.

I'll go check the ECU for 12V right now


...ok, there is no voltage at the injectors, I used the battery post as a ground.

 

SHE RUNS!

Thank you for everyone help

Connector X-11 by the firewall was not connected to connect the power from the front harness to the engine harness.