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Discussion Starter · #41 ·
Ok. Noted. Will use the 91 diagram.
So if you have a 91 NA body harness you should not have the round 4 pin plug connected to the relay nor the rectangle 2 pin plug connected to the resistor. The second resistor here is the fuel injector resistor so ignore that as it not part of the system.
If you do, then it is a turbo body harness.

OK so lets run through the OEM system and then how you have wired it.

OEM you have the Circuit Opening Relay which sends power from the Main EFI Relay to the Fuel Pump Resistor Relay. It can only do this when the key is in the STA position and when the engine is running. The FC pin grounds through the ECU controlling the safety part of the system.
Once the Fuel Pump Resistor Relay has power to pin 3 it will by default send power to pin 4 through the Fuel Pump Resistor then to splice point E2 then on to the pump. This will make the pump run at slow speed.
When the ECU deems necessary it will ground pin 1 of the Fuel Pump Resistor Relay switching it so power runs from Pin 3 to Pin 2 sending the full 12v to pump making it's speed fast.

You mention that you get power to pin 3 of the FPR Relay which makes sense. That comes from the COPN Relay. You should then have power going through the relay to pin 2 or 4 depending on what the ECU wants.
So based on your red line diagram you have added a wire from Pin 2 of the resistor to the fuel pump direct? And if you do not have this wire installed the pump does not run?
So this means you do not have the ECU switching the relay to get power from Pin 2 of the FPR Relay. You need to run a wire from Pin 2 of the relay to the pump to make the system work fully.

You need to confirm the relay is switching.

You mention there is no continuity between pin 2 of the resistor and fuel pump and also pin 2 of the relay and the fuel pump?
View attachment 84397
So, yes I do have the turbo harness when the swap was done. I literally transferred the motor and harness.
Yes correct no continuity between the FP relay, resistor and FP.
so, do I have to run a second wire from FP relay pin 2 to the FP? For example, the FP connector under the ashtray there is one small and one larger wires pinned into the connector positive side.
 

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Discussion Starter · #42 ·
Ok. Noted. Will use the 91 diagram.
So if you have a 91 NA body harness you should not have the round 4 pin plug connected to the relay nor the rectangle 2 pin plug connected to the resistor. The second resistor here is the fuel injector resistor so ignore that as it not part of the system.
If you do, then it is a turbo body harness.

OK so lets run through the OEM system and then how you have wired it.

OEM you have the Circuit Opening Relay which sends power from the Main EFI Relay to the Fuel Pump Resistor Relay. It can only do this when the key is in the STA position and when the engine is running. The FC pin grounds through the ECU controlling the safety part of the system.
Once the Fuel Pump Resistor Relay has power to pin 3 it will by default send power to pin 4 through the Fuel Pump Resistor then to splice point E2 then on to the pump. This will make the pump run at slow speed.
When the ECU deems necessary it will ground pin 1 of the Fuel Pump Resistor Relay switching it so power runs from Pin 3 to Pin 2 sending the full 12v to pump making it's speed fast.

You mention that you get power to pin 3 of the FPR Relay which makes sense. That comes from the COPN Relay. You should then have power going through the relay to pin 2 or 4 depending on what the ECU wants.
So based on your red line diagram you have added a wire from Pin 2 of the resistor to the fuel pump direct? And if you do not have this wire installed the pump does not run?
So this means you do not have the ECU switching the relay to get power from Pin 2 of the FPR Relay. You need to run a wire from Pin 2 of the relay to the pump to make the system work fully.

You need to confirm the relay is switching.

You mention there is no continuity between pin 2 of the resistor and fuel pump and also pin 2 of the relay and the fuel pump?
View attachment 84397
According to my hand drawn red line in the diagram, this is the only way to get the engine runs.
 

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Discussion Starter · #43 ·
Ok. Noted. Will use the 91 diagram.
So if you have a 91 NA body harness you should not have the round 4 pin plug connected to the relay nor the rectangle 2 pin plug connected to the resistor. The second resistor here is the fuel injector resistor so ignore that as it not part of the system.
If you do, then it is a turbo body harness.

OK so lets run through the OEM system and then how you have wired it.

OEM you have the Circuit Opening Relay which sends power from the Main EFI Relay to the Fuel Pump Resistor Relay. It can only do this when the key is in the STA position and when the engine is running. The FC pin grounds through the ECU controlling the safety part of the system.
Once the Fuel Pump Resistor Relay has power to pin 3 it will by default send power to pin 4 through the Fuel Pump Resistor then to splice point E2 then on to the pump. This will make the pump run at slow speed.
When the ECU deems necessary it will ground pin 1 of the Fuel Pump Resistor Relay switching it so power runs from Pin 3 to Pin 2 sending the full 12v to pump making it's speed fast.

You mention that you get power to pin 3 of the FPR Relay which makes sense. That comes from the COPN Relay. You should then have power going through the relay to pin 2 or 4 depending on what the ECU wants.
So based on your red line diagram you have added a wire from Pin 2 of the resistor to the fuel pump direct? And if you do not have this wire installed the pump does not run?
So this means you do not have the ECU switching the relay to get power from Pin 2 of the FPR Relay. You need to run a wire from Pin 2 of the relay to the pump to make the system work fully.

You need to confirm the relay is switching.

You mention there is no continuity between pin 2 of the resistor and fuel pump and also pin 2 of the relay and the fuel pump?
View attachment 84397
According to BGB diagram, the image shows pin 3 is contacting pin 4, therefore it should have continuity. However, per diagnostic instructions in another part of the BGB, it said to test for continuity between pin 2 and 3. I did the test, pin 2 and 3 has continuity. Pin 3 and 4 not.
 

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So, yes I do have the turbo harness when the swap was done. I literally transferred the motor and harness.
Yes correct no continuity between the FP relay, resistor and FP.
so, do I have to run a second wire from FP relay pin 2 to the FP? For example, the FP connector under the ashtray there is one small and one larger wires pinned into the connector positive side.
Ok. Makes a lot more sense now knowing you have the turbo body harness.
There is a plug behind the seat the connects the fuel pump to the body harness. Maybe check to find that and see if it is connected? BM1 on the diagram.
But yes, if all else fails, you should run a wire from Pin 2 of the relay as well as the one you have already run.
This way you have the 2 speed system working properly. As long as the ECU is able to switch the relay with the FPR pin then you are good to go.
I am not too sure about the 2 wires but I have seen that there are 2 for the turbo and 1 for the NA. Although there is only 1 wire in the body harness up to behind the seat to BM1. Unless I am wrong there and there is 2 as well.
 

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According to BGB diagram, the image shows pin 3 is contacting pin 4, therefore it should have continuity. However, per diagnostic instructions in another part of the BGB, it said to test for continuity between pin 2 and 3. I did the test, pin 2 and 3 has continuity. Pin 3 and 4 not.
Interesting. The diagram shows the relay in the default position between 3 and 4 and when the ECU grounds the FPR pin it should be 3 and 2. You will want to make sure the relay is behaving correctly as if not then you could damage your engine. I have also had to help someone fix theirs on a road trip after the just bought the car. Someone had messed with the wiring for this system and it would not run 12V, only 5V and it wouldn't start when hot and wouldn't run well when in boost. Low fuel pressure. So I used the OBD1 jumper as a temp fix to get them home.
 

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Discussion Starter · #47 ·
Interesting. The diagram shows the relay in the default position between 3 and 4 and when the ECU grounds the FPR pin it should be 3 and 2. You will want to make sure the relay is behaving correctly as if not then you could damage your engine. I have also had to help someone fix theirs on a road trip after the just bought the car. Someone had messed with the wiring for this system and it would not run 12V, only 5V and it wouldn't start when hot and wouldn't run well when in boost. Low fuel pressure. So I used the OBD1 jumper as a temp fix to get them home.
Thanks for your help.
 

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Discussion Starter · #48 ·
Ok. Makes a lot more sense now knowing you have the turbo body harness.
There is a plug behind the seat the connects the fuel pump to the body harness. Maybe check to find that and see if it is connected? BM1 on the diagram.
But yes, if all else fails, you should run a wire from Pin 2 of the relay as well as the one you have already run.
This way you have the 2 speed system working properly. As long as the ECU is able to switch the relay with the FPR pin then you are good to go.
I am not too sure about the 2 wires but I have seen that there are 2 for the turbo and 1 for the NA. Although there is only 1 wire in the body harness up to behind the seat to BM1. Unless I am wrong there and there is 2 as well.
Ok. So, if you have seen and acknowledged that for the turbo there 2 wires going into the fuel pump, then this means that I did swapped in the turbo harness and the fuel tank. What makes me wonder is why there’s no continuity from the FP relay to FP. I will investigate further.
 

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Discussion Starter · #49 ·
Ok. Makes a lot more sense now knowing you have the turbo body harness.
There is a plug behind the seat the connects the fuel pump to the body harness. Maybe check to find that and see if it is connected? BM1 on the diagram.
But yes, if all else fails, you should run a wire from Pin 2 of the relay as well as the one you have already run.
This way you have the 2 speed system working properly. As long as the ECU is able to switch the relay with the FPR pin then you are good to go.
I am not too sure about the 2 wires but I have seen that there are 2 for the turbo and 1 for the NA. Although there is only 1 wire in the body harness up to behind the seat to BM1. Unless I am wrong there and there is 2 as well.
I was thinking BM1 is the connector under the ashtray. More investigation to do. 👍
 

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I just check back there’s no connectors to be found. Remember, the chassis is of an NA.
Interesting. Maybe it was just missed and tucked away under the trim. Because an NA has a fuel pump too. It doesn't change how it was wired here. It just goes direct from the COPN Relay to BM1. But you no long have the NA body harness and fuse box.
Can you trace the F4 plug back along the fuel tank and to behind the left door area?
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Discussion Starter · #54 ·
I just check back there’s no connectors to be found. Remember, the chassis is of an NA.
I found the plug with the L-B from FP relay & Resistor pin 2 and There’s continuity from both pins. However, there’s no connector for it to reach the FP. But at least now I can make the wire reach the FP.
thanks so much.
 

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I found the plug with the L-B from FP relay & Resistor pin 2 and There’s continuity from both pins. However, there’s no connector for it to reach the FP. But at least now I can make the wire reach the FP.
thanks so much.
Excellent! That's one big step forward. You should be able to remove the wire you installed from Pin 2 on the resistor.
I wonder where it went. It should be close by maybe under the carpet. Although I see no carpet on the firewall. I'm sure you will sort it out and have it run as per OEM.
 

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Discussion Starter · #57 ·
Excellent! That's one big step forward. You should be able to remove the wire you installed from Pin 2 on the resistor.
I wonder where it went. It should be close by maybe under the carpet. Although I see no carpet on the firewall. I'm sure you will sort it out and have it run as per OEM.
Done! I found all the connectors and plug and play. The engine started up as normal. Whew! Piece of mind knowing the fuel will stop flowing in case of an accident with fuel line ruptured when engine stalled. Big thanks.
 

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So the BM1 connector just wasn't connected when swapping in the turbo body harness? For sure the NA chassis have this connector.
When installing a Supra pump in an NA chassis, I have run an additional #14 wire from the fuel pump resistor and relay (which I added), to the fuel pump (F4) connector. I don't feel comfortable with the OEM wiring carrying the current drawn by the Supra pump at full 12v mode.
 

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Discussion Starter · #60 ·
So the BM1 connector just wasn't connected when swapping in the turbo body harness? For sure the NA chassis have this connector.
When installing a Supra pump in an NA chassis, I have run an additional #14 wire from the fuel pump resistor and relay (which I added), to the fuel pump (F4) connector. I don't feel comfortable with the OEM wiring carrying the current drawn by the Supra pump at full 12v mode.
I noticed the factory wire for FP seems a bit small to me. However I’m running with turbo fuel pump so I think it’s ok.
as for the BM1 connector, it wasn’t plugged in during swap. I was a newbie’s at engine swapping. The NA chassis doesn’t have the BM1 connector but I must have transferred all harnesses from the Turbo donor car into the rolling shell NA body the previous owner stripped clean for respray inside and out.
 
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