Fuel Line Cut off
Fuel Line Cut off
I have a 1987 fc turbo II. Recently i've had some issues with the engine flooding and not starting due to stalling. A friend who previously owned a rx said there is a way to put in a fuel line cut off switch. You just have to splice into a wire under the steering, was wondering if anyone knew which wire i need to splice thanks!!!
This picture from the FSM shows the Circuit Opening Relay that turns the fuel pump off if the engine stalls. It’s a located under the dash next to the steering column and has a yellow base, so you can’t miss it.

The B wire (black with a white stripe) is the power supply from the 15A ENGINE fuse and the Fp wire (blue with a red stripe) goes to the fuel pump. The switch can go into either of these wires, it doesn’t matter which. Simply cut the wire, extend each cut end to your chosen switch location using the same or thicker gauge wire and terminate them onto the switch. Note that the STA wire is also black with a white stripe, but it’s thinner. Make sure you get the right wire.
The B wire (black with a white stripe) is the power supply from the 15A ENGINE fuse and the Fp wire (blue with a red stripe) goes to the fuel pump. The switch can go into either of these wires, it doesn’t matter which. Simply cut the wire, extend each cut end to your chosen switch location using the same or thicker gauge wire and terminate them onto the switch. Note that the STA wire is also black with a white stripe, but it’s thinner. Make sure you get the right wire.
Although NZConvertible is right, I'd cut the "ground" wire.
The wires NZConvertible described are the high-current wires of the relay.
If you interrupt the low-current side of the relay, it effectively does the same thing.
If you do interrupt the circuit on the high-current side, you need to make sure the switch or the extra relay is able to handle the higher current (15A - same as the fuse).
-Ted
The wires NZConvertible described are the high-current wires of the relay.
If you interrupt the low-current side of the relay, it effectively does the same thing.
If you do interrupt the circuit on the high-current side, you need to make sure the switch or the extra relay is able to handle the higher current (15A - same as the fuse).
-Ted
Ted, that won't work unless you use two switches or a double pole switch. The circuit opening relay has two coils that can operate the switch, one connected to the AFM safety switch (the Fc wire in the diagram above) and one connected to the Start circuit (the STA wire). Interrupting only one of these will still allow the fuel pump to run on starting.
A 15A switch is easy to find and pretty cheap.
A 15A switch is easy to find and pretty cheap.
Last edited by NZConvertible; Jun 12, 2005 at 07:55 AM.
He could disable that *START* circuit by pulling off the small black/white wire if a turbo or black/red wire on a non turbo and do what the Ted said. I find that particular coil just redunant and not required (proven over several months).
Sorry, just couldn't help from posting that.
Sorry, just couldn't help from posting that.
Originally Posted by NZConvertible
Ted, that won't work unless you use two switches or a double pole switch. The circuit opening relay has two coils that can operate the switch, one connected to the AFM safety switch (the Fc wire in the diagram above) and one connected to the Start circuit (the STA wire). Interrupting only one of these will still allow the fuel pump to run on starting.
A 15A switch is easy to find and pretty cheap.
A 15A switch is easy to find and pretty cheap.
This guy is telling the truth. I just wired mine (the ground method) before I found this thread and the fuel pump would not cut off. Guess I will switch it off with the B wire now.
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Oh, I didn't say a 15A switch is hard to find.
But, I think I can confidently say that a sub 2A one is *EASIER* to find than a 15A one.
On top of that, a lower current rated one is usually cheaper; we all know FC owners are cheap asses.
Just to pull out my trump card, lower current electrical components (in general) are more reliable.
Higher current stuff tends to "burn out" faster...
-Ted
But, I think I can confidently say that a sub 2A one is *EASIER* to find than a 15A one.
On top of that, a lower current rated one is usually cheaper; we all know FC owners are cheap asses.

Just to pull out my trump card, lower current electrical components (in general) are more reliable.
Higher current stuff tends to "burn out" faster...
-Ted
Originally Posted by are_one
This guy is telling the truth. I just wired mine (the ground method) before I found this thread and the fuel pump would not cut off. Guess I will switch it off with the B wire now.
If you had just pulled the black/red wire(non turbo car), off the relay and tied it back and done what you said you did, then the fuel would have cut.
Originally Posted by RETed
I think I can confidently say that a sub 2A one is *EASIER* to find than a 15A one.
There are various ways to do this, I just posted the easiest way for people who ask. If you already know about disabling relay coils and wiring double-pole switches, you're probably not going to be asking how to do this here are you?
The Spyder made a VERY good write up for this 
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/my-fuel-cut-switch-write-up-pictures-343361/

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/my-fuel-cut-switch-write-up-pictures-343361/
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