rOt0rHeAd

I have a 90 N/A that I am having trouble getting started, and I have got a few questions. Should the fuel pump come on with the ignition switch in the IGN position, I am talking about the position before the start position? Also, what role does the circuit opening relay play in the fuel system?

MountainTurbo

No, the pump does not prime by itself with the key to "on". However, if you turn the key to on and jumper the test connection or open the AFM door, the pump should turn on.

The relay your talking about turn the pump on during cranking, and once the car is started the flapper door of the AFM being open is what keeps the pump running. IIRC.

Hellkat

There should be a yellow 2 pin connector near ur airbox that you can jump in order to prime or test ur pump. Just take a wire and cross em. If ur pump fails to turn on, try see if ur grounds are grounded. Also rx7 fuel pump is quiet compared to other pumps so u might have to open ur gas cap to look for the noise. Also make sure u have at least a quarter of a tank, for some reason mine dident start because it wasnt
sumberged enough when i released my fuel pressure and i had to fill it to quarter.

HAILERS

The fuel pump is fed 12vdc thru a set of contacts in the Circuit Opening Relay.

Those contacts are open unless: The key is HELD to START or the key is to ON and the engine is running.

So there are two seperate ways for that Circuit Opening Relay to close the contact. One way is for a switch in the afm to *make* and supply a ground to the Circuit Opening Relay so it's coil can pull in. Or there is another coil in the Circuit Opening Relay that can pull in IF you hold the key to Start.

Go look at the wiring schematic for the Circuit Opening Relay. It's free and a online download.

Bottom line is the Circuit Opening Relay has two coils, either of which will close the contacts and supply voltage to the pump. One coil is dependent on 12v going to it from the START position and the other coil is dependent on a GROUND from the AFM OR the Fuel Pump Check Connector. See the schematic and it will all make sense.

HAILERS

As for what HOT means: If you look at your series four FSM, page 4A-80, you'll see that when they checkout the FPR solenoid, they jumper the Intake Air Temp Sensor with a 2-3K ohm resistor to simulate HOT.

Now if you look at the next page over, page 4A-81, there is a chart there. It shows that at 122*F the resistance of that sensor is 11.85K ohms plus/minus 1.19K ohms. And at 185* the resistance of that sensor is 3.5K ohms plus/minus 0.35 ohms. So I assume from those figures, HOT is when the Intake Air Temp Sensor is somewhere around 190-200 degrees and above.

If its hot on a series four, the book says no vacuum will go to the FPR for 50-90 seconds.

The series five book, when talking about the Fuel Pump Resistor and Relay, in the OutPut Devices page, says it'll put out a full 12vdc during HOT conditions at idle. That explains the clicking from the Fuel PUmp Resistor Relay package sometimes.

And the series five fsm says/mentions the reason for no vacuum to the FPR during HOT conditions (for 50-90 seconds), is to prevent Percolation of the fuel in the rails.