fc3sguy

I had a question. Is it normal when you turn on your ignition ON and fuel pump doesn't get any voltage? I thought it supposed to pressurize the fuel system. In my case it cant do it since my tank is empty. Or does it turn on only once engine is running. I'm asking about it because right now my whole intake is in pieces and I can't start the engine.

Ranzo

In normal operation Yes the pump should prime. It will run for 2.9 seconds or until the engine is running. If your intake is in peices I might assume that the AFM is not connected and this would prevent the Pump from turning on.

NZConvertible

The fuel pump will not run unless airflow is detected by the AFM (i.e. engine is running). If the engine stalls the fuel pump's power is cut. This is to stop fuel pumping out of broken fuel lines if you spit the car into the scenery. Raw fuel + hot car parts = very bad...

For testing purposes and to prime the fuel lines, you can bypass the safety switch in the AFM by jumpering the little yellow plug by the RHS strut tower in the engine bay. This will allow the fuel pump to run with the ignition switched on. For obvious safety reasons, remove the jumper wire before driving the car.

HAILERS

1. Turning the key to ON will NOT operate the pump at all.
2. Turning the key to START, WILL make the pump run until you let the key return to ON, where upon the pump will NOT run UNLESS the car starts,then the pump will run.
3. If you pull the wire from the Circuit Opening Relay that energizes the relay when the key is put to START, I find the pump will still run because you draw enough air across the afm to MAKE the circuit in the afm that energizes the Circuit Opening Relay. I delibertly pulled that wire out of my 87turboii relay base to see if there are any consequenses. Ain't got none yet.

4. The other way of making the pump run has been described in a post above.

fc3sguy

ok I did the thing with the jump wire and the yellow plug and the pump started working. Now I know where the main relay and fuel pump resistor relay are located, but I don't know where is that circuit opeing relay located and what is its. I need to get all that crap straight in my head before I start messing with rewiring my fuel pump. thanks for help so far

HAILERS

Under the dash. Just above the steering wheel column. Look for a yellow relay base. Your profile says something about a 86na???? You don't have a fuel pump resistor relay in that model car. I must have misread/understood something.

NZConvertible

That'll be the fuel injector resistor pack, for the low-impedance injectors. S4 NA's don't have the resistor/relay for the pump.

fc3sguy

Sorry, I forgot to mention, my profile is not updated. Car I'm talking about is 87 TII. Oh and YES, thanks for reminding me NZConvertible about the fuel injector resistor pack. That's another thing I tried to Find on my TII. Reason for that is somebody who owned this car before me has cut off S4 and splice S5 injectors in their place. Somebody told me to check to see if they haven't bypassed the resistor pack or something, but that's where I don't get it. Now why low impedence injectors need a resistor pack. Don't resistors raise the impedence. How many ohms does the ecu have on injector outputs? Please help me solve this...

NZConvertible

All FC ECU's need to see high impedance from the injectors. Since the early (86-87.5) injectors are low impedance, the resistor pack is added in line with the injectos power supply so the ECU is happy.

fc3sguy

Thanks NZ, that would explain it. Ok so here's another thing that bothers me. I know that TII fuel pumps are operating at 9V when engine is idling or just cruzing but what makes the ecu give the signal to switch operating voltage to 12V, is it boost or rpm. My concers is that I'm using FCD and ecu is seeing low boost all the time, so I'm worried that it might also keep the fuel pump working at 9V all the time. Should I be concerned about this?

HAILERS

https://www.rx7club.com/forum/attach...&postid=871818

The pressue sensor was colored for another thread, not this one. The *0* are the players, not the *X*'s

NZConvertible

From my testing, it switched at 2-3psi boost. Don't worry about the FCD, it won't be making any difference.

HAILERS

Dittos to the above post. Just run a meter to the fuel pump wire and watch it while driving.

fc3sguy

alright thanks,
I ll keep an eye on it once I get my car running. One last question. Does anyone know where the injector resistor pack is located. I wanna make sure that it hasn't been bypassed or anything before I stick my old low impedence injectors back in. I don't wanna fry my ECU. Thanks everybody, this task went alot smoother for me.

HAILERS

Its bolted to the right fender, directly below the afm/filter assy. Just remove the afm assy and there it is. It has an aluminum cover on it and is held on with two nuts.