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Discussion Starter #1
Hello. I've got a problem with the fuel relay. I've spent 18 months building this bike and only have the bodywork to paint.
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The bike stopped after 10 minutes of running. It has a new fuel pump, strainer and filter and I've tested it whilst in the tank and it runs perfectly. The problem is I have power to the relay via the orange/white wire, but no power out from the relay through the yellow/red wire. I've got 3 brand new relays and none seem to work. If I take the relay off and connect the orange/white directly to the yellow/red wire the pump runs and the bike runs perfectly. I'm at an absolute loss. It's driving me mad. Please help. Thank you.
 

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It may simply be a bad fuel pump fuse, or a poor connection in that circuit.

The power for the fuel pump and injectors comes through the Orange/blue wiire at the FP Relay. That wire should be at 12V all the time - even when the key is off. It is connected directly to the starter relay via the fuel pump fuse.

Have a look at that wire while referencing the wiring diagram, and you will likely find the problem.

The Orange/wht wire merely powers the FPR coil in order to activate the relay.
 

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Discussion Starter #3
Thanks for your reply, but the pump, injectors seem to be
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powered by the red/ yellow wire as it shows in the Haynes wiring diagram.
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Thanks for your reply, but the pump, injectors seem to be powered by the red/ yellow wire as it shows in the Haynes wiring diagram. View attachment 65022
Yes, that is true. However, the Yel/red wire is powered by the Org/blu wire.

You will notice in the image in the quote above, when the fuel pump relay closes the Org/blu wire is connected to the Yel/red wire. Then the fuel pump and injectors are powered.

If the Org/blu wire is dead, then the Yel/red wire will be dead also. That's why we need to look further 'upstream' to see where the problem is.
 

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I absolutely detest bike electrics 🤬
And yet, you still bought a TL? :)


Have you verified whether the fuel fuse is still good?
Is there any voltage on the Orange/blu wire?
If not, go back to the large white gang connector near the headlight on the right side, and probe on the Org/blu wire at that point. Also probe on the corresponding Brown wire on the other side of the connector. Any voltage?
If not, go to the fuse box and probe on both sides of the Fuel fuse (#5 in the diagram). Any voltage?
If not, go back to the large white gang connector and probe on the Red/wht wire. Any voltage?

Let us know the results, and we can go from there.
 

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Discussion Starter #7
If I wire the orange and white wire directly to the red and yellow wire in the plug that goes into the fuel relay, the pump runs and the bike runs perfectly. However the pump continues to run whilst the ignition is on but with the bike not running. When it's supposed to be running properly the pump winds up for about 3 seconds to prime it when you turn the ignition on then stops. It only starts again when the engine is running! The two other wires in the fuel relay lead are for the low and very low fuel sensors that are attached to the fuel pump frame. On the wiring diagram I can see no connection for them to the fuel pump and injector system!
 

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If I wire the orange and white wire directly to the red and yellow wire in the plug that goes into the fuel relay, the pump runs and the bike runs perfectly. However the pump continues to run whilst the ignition is on but with the bike not running.
Correct. That is to be expected.

When it's supposed to be running properly the pump winds up for about 3 seconds to prime it when you turn the ignition on then stops. It only starts again when the engine is running!
Yes. This is normal.


The two other wires in the fuel relay lead are for the low and very low fuel sensors that are attached to the fuel pump frame. On the wiring diagram I can see no connection for them to the fuel pump and injector system!
No, not quite. Maybe you were confused by the wire diagram.
The fuel level sensor wires do come from the fuel pump frame (pump plate), but they do not go to the fuel pump relay. However, you are correct in that the fuel level sensors have no influence on the fuel injection system.

These are the wires in the fuel pump RELAY connector.
ORANGE/blue - this wire is "unswitched." It is always at 12 volts because it is connected directly to the battery through the starter relay connector. It carries power from the fuse box (fuel fuse, 10 amp) to the fuel pump relay in order to power the fuel pump and the injectors.

YELLOW/red - this wire is connected to the Orange/blue wire when the fuel pump relay is activated. This is the wire that carries power from the fuel pump relay to the fuel pump and injectors.

ORANGE/white - this wire is "Switched." It only has 12 volts on it when the ignition switch is turned ON. It is the primary distribution wire for the IGNITION circuit (protected by the 10 amp ignition fuse) . It also provides power to the ECM. It is only connected to the fuel pump relay to provide power to the relay's coil to allow it to be activated.

YELLOW/blue - this wire is the control line between the ECM and the fuel pump relay. When the pump needs to run, the ECM drives this wire low (to about 1 volt) in order to activate the fuel pump relay. This happens during the pump "prime" cycle, and obviously when the engine is running.


Have you taken any voltage measurements on the Orange/blue wire?
 

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Discussion Starter #9
Will do thanks, but when I connect a spare battery to the pump in the tank. Negative to the black/white and positive to the red/yellow, the pump runs??????
 

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Discussion Starter #11
I have had the fuse box off and tested the connections. If I put the neg lead of the tester onto the neg terminal on the battery, I get 12V from the the powered side of the fuse holder, but if I put the positive and negative leads of the tester on both terminals of the fuse holder, there is no voltage. I have tested the ohms rating across them also and nothing. Bad earth to the fuel fuse you think?
 

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..... but if I put the positive and negative leads of the tester on both terminals of the fuse holder, there is no voltage. I have tested the ohms rating across them also and nothing. Bad earth to the fuel fuse you think?
There is no "earth" connection to the fuse, per se'.
The 'conventional' current flow is in this order: battery positive; fuse; load (pump, relay, ecm, light bulb, etc.); battery negative.
When the system is working properly, ~98% of the voltage is dropped across the load, not the fuse.
Therefore, since you are measuring across the fuse box terminals with the system powered up, very little voltage, if any, will register on the meter.
If the fuse were open, then voltage would be measured.

Note: you are probably aware of this, but the ohm meter cannot be used on a circuit that is powered up. The readings will be erroneous.


Since your fuse test here seems to indicate the fuel fuse is OK, the problem must somewhere else in the fuel circuit. Next place to check is the Orange/blu wire at the large white gang connector. This is a common problem area.
 

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Discussion Starter #13
Thank you, but there is no big white gang connector. I have attached a picture of the three connectors. The top one is for the right bar switch.
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Apparently, your loom has been modified. I see a large bundle of wires with crimped splices and tape above your hand in your photo. That is where the large white connector should be. Someone has likely removed it.

This photo shows the large white gang connector. This is the front loom from my TLS when I was installing the headlight relay mod. The white connector, and the black one next to it, are what connect the front loom to the rear loom.

DSCN5230 by Tony Six5, on Flickr


At any rate, follow the Orange/blue wire from the fuel pump relay to see where it goes. You will likely find a problem in that bundle of wires with the tape and crimped splices.
 

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Discussion Starter #15
Those crimped wires were from the right handlebar switch gear. I've literally just put a brand new one on. Unfortunately it's a European one and has no light switch so they're hard wired on all the time like my SV
 

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Discussion Starter #18
I have fixed it with your help. I followed the brown wire from the fuse box which joins to the orange and blue. It had come loose where it was joined. When the ignition is turned on now the pump runs for 3 seconds to prime, then stops and the bike strikes up first time. Thank you so very much, you're a ****ing hero! 👍
 
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