We went to start the RX-7 last night for the first time, no fuel pressure (no fuel in the lines). Missed the instruction on having to pressurize the fuel system by using the jumper,

in every car I've been in (with electric fuel pumps anyway) the fuel pump kicks on for a couple of seconds when you first turn the key on.. I got nada when I turned the key, no voltage to the pump.

Now, when I set the jumper, pump ran fine..

Now, I read somewhere that the AFM has an output that goes to one of the solenoids that tells it that air is flowing, no airflow, no fuel pump.. Is that correct? I don't want to tear down the electrical system looking for a goof if that is correct.

BTW, did anyone notice that the fuel pump solenoid isn't wired the same way in the car vs. the FSM? The FSM calls for a 6 prong round connector.. I've got 4 prongs in a square/rectangle.

Oh, all on an 88 N/A

PaulC

 

TTT

PaulC

 

That's the way I read the diagrams. No air flow. No fuel pressure. Never heard my fuel pump run when the key is merely switched to on either.
'86 N/A

 

Yeah, I just bought an '87 that has been sitting for 3 yrs. Pulled the fuel pump and found the rect. speed fitting as well. Pump was shot due to being submerged in "varnish" for so long. got good used replacement pump. Am getting tank cleaned prior to reinstall- 1/2 inch thick sludge on bottom & good coat on sides. (PO parked it w/ half a tank!?!?!) But, no air- no gas, really? These rotaries do be strange beasties... That might stop me from embarrassing myself when I try to take back the new pump. But jumping the leads will start the pump and pressurize the system? I'm still learning about the way Mazda does things.

The more I learn, the more I learn there is to learn...
TMCX

 

Yup, that's correct. The fuel pump doesn't run when you turn the key. It runs when the AFM opens up. You can either lift the door on the AFM, or jumper the wires to pressurize the system.

 

k, thanks guys.

TMCX,

The jumper is a yellow connector on the passenger strut tower.. Jump those leads, and the fuel pump will run with the power on.

PaulC

 

Yep, correct. It’s a safety feature that most EFI cars have. It means if you have a crash and the engine stalls but the ignition is still on, the fuel pump doesn’t pump fuel out any broken fuel lines. I’m sure you can see the benefit if this...
If you follow the wiring diagrams, you can see when the key is in the start position, the safety switch in the AFM is bypassed to run the pump while cranking.

 

Is that just on the series4 setup, cuz in the process of designing a new intake for my 90gxl, I'm able to start the car with the afm disconnected. It ran hella rich though smoking up the entire block.

 

No, S5's too.The engine shouldn't run at all with the AFM unplugged! WTF have you done to it?!

 

Well the car is as stock as it can possibly get when I first picked it up, and all wires look factory so I assume there is no hidden haltech(I wish) that is running it.

One of these days I'm going to see how it runs WOT without that toilet plunger in place. But like you said, it's weird. Maybe it partially operates on memory, like when we flood the engine it will never start even if we wait for weeks and months.