No Power to Fuel Pump???
04-19-06, 11:25 AM
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No Power to Fuel Pump???
ok so when i bought my TII the guy said he had to direct wire the fuel pump and thats why there was this little switch i had to hit every time i turned the car on or off......so i just thought he meant he just put in a fuel cut switch to save the car from flooding...........
turns out it really is directly wired.....i followed the wire from the switch and pulle dup the rear carpet to access the fuel pump....and the power wire from the switch is tied into the wire for the fuel pump...nothing was cut just piggy backed.....
so basically when i stop the car, i can turn the key to off and remove it and the car still runs until you flick the switch to off...
i havnt tried to disconnect the wire to see what happens but im assuming the fuel pump wont turn on without this direct wiring.....what could be the cause of this???? seems very bizarre to me.....
also on a side note does anyone know where i can find just the cover part of the gas tank that holds the fuel pump....its rusted and missing a few screws...which is the reasoning for the fuel leak from my previous thread....i can only seem to find just the tank itself.....
turns out it really is directly wired.....i followed the wire from the switch and pulle dup the rear carpet to access the fuel pump....and the power wire from the switch is tied into the wire for the fuel pump...nothing was cut just piggy backed.....
so basically when i stop the car, i can turn the key to off and remove it and the car still runs until you flick the switch to off...
i havnt tried to disconnect the wire to see what happens but im assuming the fuel pump wont turn on without this direct wiring.....what could be the cause of this???? seems very bizarre to me.....
also on a side note does anyone know where i can find just the cover part of the gas tank that holds the fuel pump....its rusted and missing a few screws...which is the reasoning for the fuel leak from my previous thread....i can only seem to find just the tank itself.....
04-19-06, 12:16 PM
#2
The parts manual for the S5 (only one I have handy) does not show a separate part number for that "cover". Apparently it is part of the fuel pump assembly. But I would suggest you talk with a savvy Mazda parts person to be sure. Otherwise, try a junk yard or salvage company specializing in Mazdas.
04-19-06, 04:00 PM
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It sounds to me that the NEW wire to the fuel pump is backfeeding into the electrical circuit and keeeping the bus fed until the NEW switch is cut off. More or less common sense and you figured that out.
Why he wired it like that? Only he knows. It's propably out of ignorance. Personally I'd cut that NEW wire and see if you can start the car without it.
The original path for power to the pump is from the ignition switch...........to the Circuit Opening Relay...........to the Fuel Pump Relay and Resistor in front of the afm..........to the fuel pump connector.
Just download the wiring schematics for a 88 model that is free and online
Fuel pump runs.....1. If the key is ON and the jumper is in the fuel pump check connector (engine can be not running_
2. IF the engine is running and the switch in the afm is working (it puts a gnd on the Circuit Opening Relay to pull it in).
3. IF the key is HELD to START the pump runs. When you let go it stops running right then and there if the engine did not start (gnd signal switch in the afm not made).
The fuel pump does NOT run just by turning the key to ON.
Go here: https://www.rx7club.com/forum/attach...postid=1398836
Why he wired it like that? Only he knows. It's propably out of ignorance. Personally I'd cut that NEW wire and see if you can start the car without it.
The original path for power to the pump is from the ignition switch...........to the Circuit Opening Relay...........to the Fuel Pump Relay and Resistor in front of the afm..........to the fuel pump connector.
Just download the wiring schematics for a 88 model that is free and online
Fuel pump runs.....1. If the key is ON and the jumper is in the fuel pump check connector (engine can be not running_
2. IF the engine is running and the switch in the afm is working (it puts a gnd on the Circuit Opening Relay to pull it in).
3. IF the key is HELD to START the pump runs. When you let go it stops running right then and there if the engine did not start (gnd signal switch in the afm not made).
The fuel pump does NOT run just by turning the key to ON.
Go here: https://www.rx7club.com/forum/attach...postid=1398836
Last edited by HAILERS; 04-19-06 at 04:06 PM.
04-19-06, 05:31 PM
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well the car doesnt start without turning the switch to on, so this is the same as removing the wire....because the original factory wires are in place and the power wire is spliced in with a connector
so this leads me to believe that one of the relays are bad.....
how do i go about figuring that part out??
or is this a wrong conclusion
so this leads me to believe that one of the relays are bad.....
how do i go about figuring that part out??
or is this a wrong conclusion
04-19-06, 06:05 PM
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Get a meter out. Pull the Circuit Opening Relay from just above the steering wheel.
Jumper the Fuel Pump Check Connector near the right front strut tower (yellow, two socket).
In the socket for the relay, the BROWN wire should read as a ground and if you turn the key to ON, the large Black/White wire should have battery voltage.
Also the pure black wire should show as a ground.
If you HELD the key to START you'd also see 12v on the small black/white wire. This is not required for right now so don't do that part.
If you had the grounds and the voltage on that Circuit Opening Relay, then go to the Fuel PUmp Relay and REsistor (right front of the engine bay, just infront of the afm/airfilter box), and pull it's plug off. With the fuel pump check connector still in place and key ON, see if theres 12v on the Blue/Red wires (two) in the plug.
Anyway, a simple digital meter and the schematic above should be all that's needed to figure things out. Circuit Opening Relays are pretty reliable and imho rarely fail. The biggest failure of that relay imho is that the contacts get worn/old/pitted and might not supply enough current to the fuel pump after fifteen years of use.
If you had 12v on either of the Blue/Red wires and the pump does not work, then jumper a wire b/t either of the Blue/Red wires to either of the pure Blue wires and if the key is On the pump should work.
I'd disconnect the wire that the previous owner put in before you do either of the above because it'll just confuse the issue.
The Main Relay plays no part in this fuel pump problem.
Jumper the Fuel Pump Check Connector near the right front strut tower (yellow, two socket).
In the socket for the relay, the BROWN wire should read as a ground and if you turn the key to ON, the large Black/White wire should have battery voltage.
Also the pure black wire should show as a ground.
If you HELD the key to START you'd also see 12v on the small black/white wire. This is not required for right now so don't do that part.
If you had the grounds and the voltage on that Circuit Opening Relay, then go to the Fuel PUmp Relay and REsistor (right front of the engine bay, just infront of the afm/airfilter box), and pull it's plug off. With the fuel pump check connector still in place and key ON, see if theres 12v on the Blue/Red wires (two) in the plug.
Anyway, a simple digital meter and the schematic above should be all that's needed to figure things out. Circuit Opening Relays are pretty reliable and imho rarely fail. The biggest failure of that relay imho is that the contacts get worn/old/pitted and might not supply enough current to the fuel pump after fifteen years of use.
If you had 12v on either of the Blue/Red wires and the pump does not work, then jumper a wire b/t either of the Blue/Red wires to either of the pure Blue wires and if the key is On the pump should work.
I'd disconnect the wire that the previous owner put in before you do either of the above because it'll just confuse the issue.
The Main Relay plays no part in this fuel pump problem.
Last edited by HAILERS; 04-19-06 at 06:11 PM.
04-19-06, 06:14 PM
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OR if you have some adventure in yourself, pull the Circuit Opening Relay and jumper the large Black/White wire to the L/R or Blue/Red wire. If the key is ON, the pump should run. Make sure your previous owners wire is out of the circuit. IF the pump runs, then either your relay is bad OR the ground on the Brown wire at the relay is MISSING.
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04-20-06, 07:59 PM
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ok so i jumpered out the fuel pump check connector and pulled the plug on the circuit opening relay.....
checked for voltage with the key on and got nothing.....used the brown as a ground and checked the fat black/white wire also tried the small black/white wire with key in start....nothing no matter what combination i tried
what does this mean???
also i noticed a smaller plug with two wires taped up to the COR plug...it had a medium sized yellow wire (like 12 gauge) and i think a small black wire....what is this for? diagnostics? or is it supposed to be plugged in somewhere?
checked for voltage with the key on and got nothing.....used the brown as a ground and checked the fat black/white wire also tried the small black/white wire with key in start....nothing no matter what combination i tried
what does this mean???
also i noticed a smaller plug with two wires taped up to the COR plug...it had a medium sized yellow wire (like 12 gauge) and i think a small black wire....what is this for? diagnostics? or is it supposed to be plugged in somewhere?
04-20-06, 11:08 PM
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The ENGINE fuse feeds the relay black/white wire.
The ENGINE fuse is fed by the ignition switch.
https://www.rx7club.com/forum/attach...postid=1398836
The ENGINE fuse is fed by the ignition switch.
https://www.rx7club.com/forum/attach...postid=1398836
05-09-06, 08:53 PM
#11
Originally Posted by HAILERS
The ENGINE fuse feeds the relay black/white wire.
The ENGINE fuse is fed by the ignition switch.
https://www.rx7club.com/forum/attach...postid=1398836
The ENGINE fuse is fed by the ignition switch.
https://www.rx7club.com/forum/attach...postid=1398836
Im trying to find out which line I need to install this switch in to be able to turn off the fuel pump so my car doesnt flood when I turn it off.
05-09-06, 09:40 PM
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just do a search for fuel cut switch
i found a bunch
but essentially if you splice the big black/white wire into the switch you will have a fuel cut switch
if i remember again its the biggest wire on the plug and in the middle on the top
i found a bunch
but essentially if you splice the big black/white wire into the switch you will have a fuel cut switch
if i remember again its the biggest wire on the plug and in the middle on the top
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