1st Generation Specific (1979-1985) 1979-1985 Discussion including performance modifications and technical support sections

Fuel pump cut relay

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Old 05-21-10, 11:26 PM
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WA Fuel pump cut relay

I just got a new fuel pump (mine died) and i installed it. i turned the car on and it ran for about 20 to 30 sec before it would choke out..... I could pump it and start it again and it would do the same thing.

I looked in the repair book and found where I could test the fuel pump cut relay. I jumpered it and the car would run and rev and hold at whatever i would want it to... I pluged the relay back in and it would choke out again..

I called around looking for this relay and no one has one or can get one. Does anyone know where i can get one. Or what would happen if I just left it jumpered. Maybe jumper it and put a 5amp or 10 amp fuse on the jumper wire to make sure i dont blow something..

Has anyone else had this problem?
Old 05-22-10, 12:05 AM
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A lot of guys just jumper them, including myself. My relay died early last year, jumped it and no issues since then. The only difference is that the pump will run when the key is turned on, rather than waiting until the motor is cranking.

But, before you jump it, is your car an 84 or newer? If it is, then see if you have spark on the trailing (upper) spark plugs. If the trailing ignition is not working, then neither will the fuel pump relay. If your car is 83 or older, this does not apply.

Good luck.




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Old 05-22-10, 01:49 AM
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I have a 85 GS model. I will check for spark in the morning.. If I have no spark what could be my problem? I just put new plugs in it (NGK 2329) have been trying to come up with the money for the wires, cap and rotor.
Old 05-22-10, 01:50 AM
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Oh also. Should i fuse the jumper or just straight jumper it?
Old 05-22-10, 11:56 AM
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I tested for spark and I have spark on the trailing plugs.
Old 05-23-10, 12:04 AM
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So i tried a relay i know was good and i got the same thing. I put the relays in a different rx7 and that one ran fine. What kinda problems an i looking at now?
Old 05-23-10, 06:35 PM
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Blown fuse, bad wiring, bad fuel pump. Check the fuses, check for power at the fuel pump relay, check for power at the fuel pump. If all that is good then your pump is bad.
Old 05-23-10, 11:23 PM
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Just bought a new fuel pump, I have power to the pump. Fuses are all good. Tested the wires to the fuel pump cut relay and i have power. The only thing i can think of is maybe a faulty ground to the ECU from the pump cut relay
Old 05-24-10, 09:40 AM
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Just because it's new doesn't always mean it's good If there's 12v at the fuel pump itself, check the ground wire. Use the meter on ohms, from the wire to anywhere on the frame should be 0ohms, or at least less than 5. If that's good and you're still not getting fuel pressure then the new pump is junk.
Old 05-24-10, 10:24 PM
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I put a jumper in it and put in line 10 amp fuse. works great!
Old 05-24-10, 11:54 PM
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I took the original fuel pump positive wire to a 30a relay for the trigger. Then ran a direct line
form the battery to the relay, to the pump positive. Pump ground was on the frame, did not
reground the stock fuel pump ground wire. It is a little quieter now than reusing the stock fuel
pump wires, plus the pump doesn't pulse with the turn signal/brake lights/any electrical load. It
also seems like my other electrical's are more "stable", for lack of other words.
Old 05-25-10, 08:17 AM
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where is the fuel cut relay
Old 05-25-10, 10:43 AM
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anyone here
Old 05-25-10, 11:07 AM
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Under the steering wheel...
Old 05-26-10, 02:06 AM
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The fuel pump cut relay is under the dash (you have to get under there to see it) and its round and is bolted by its self. (no other relays by it)
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