steve post

does any one know how fuel cut off relay works and what its purpose on 85 rx7. I can not get fuel from pump unless I jump out relay does car have to be running before fuel pumps operates

Rx-7Doctor

iTrader: (13)

You have to be cranking the motor before the fuel pump starts. This is a safety feature in case you get in an accident to prevent fuel from being delivered while the motor is not running.

steve post

thanks so the relay must start the pump when I crank engine

Rx-7Doctor

iTrader: (13)

The relay is there to feed power to the pump once you start to crank the motor.

trochoid

iTrader: (6)

Is this a 12A or 13B engine? Iirc, only the FI engine has the jumper. On the FI relay, it's 2 stage. In the start position, the pump comes on, once the engine has started, the flapper door in the afm closes the circuit when the key is returned to the run position. This setup also helps prevent the engine from flooding, especially with older, leaky injectors.

steve post

12a

blazer1313

there is a post recently about how to check to see if your relay for your fuel pump is ok or not. there is 2 i believe..one under the passenger side floorboard and the other under the drivers side dash...I beleive....

cdrad51

I believe you got it wrong. There's only one - under the dash.

cdrad51

At least it should. Unless there's something wrong with your trailing ignition. Your relay might be fine. Is your tach working?

Stevan

iTrader: (17)

blazer 1313 may be refering to the control module, or ecu under the carpet on the right side. I think I read(Rx7Carl) that besides emissions, the unit is only needed for the fuel pump cut relay function.
I believe RX7Doctor is correct as usual, it is a safety feature. Iv'e replaced mine and keep a jumper wire with a diagram for which terminals to jump tied to the relay with a bread tie.

steve post

no tach working

cdrad51

Are you saying, "no, tach is working" or "no tach is working (tach is not working)?"

Rx-7Doctor

iTrader: (13)

These, and other questions on the usage of the "English" language when we return,lol..

steve post

tach is not working

Rogue_Wulff

Check the trailing ignitor, as the tach gets it's signal from the trailing. That same signal also tells the safety cut relay to turn on the fuel pump.

thunder01

So Can the flapper door not working properly also cause the car not to start i.e.
flooding etc.

Rogue_Wulff

Assuming that you are talking about an SE with EGI. Yes, the "flapper door" in the AFM sticking open can cause flooding issues, and sticking shut can cause the fuel pump to not be turned on.

thunder01

YES SE EGI but if I hold the pedal down and try not to over crank it, it will start.
BUT if it sits for a hour or two start fine. This might be a different issue but it is something I can check. Thanks

trochoid

iTrader: (6)

Now you're back to leaking injectors.

Rogue_Wulff

Odd how that keeps coming up, ain't it?