Article [13] ST1300 - Fuel Pump Circuit - Fault Diagnosis

Re the circuit diagram above. I can understand why you have come to that conclusion from that section of the diagram. It is difficult to tell what is happening when you have just a small section of the diagram, which is why I teased out all if the important connections and relays and redrew them so that they could be read from left to right. The power has to come from a fused supply so I have put that on the left. @woodybelle says that is fuse L in the rear fuse box. I don't know, mine is a Uk bike so I have no way to verify.
The circuit finishes when the other end meets up with earth - the negative battery post.

But you can confirm that power is going into the ECM quite easily without having the ECM in place. Bike upright, ignition on. Check the voltage on the purple/black wire going into the bank angle relay. 12v ish. Now check the bk/white lead coming from the bank angle relay. That should be the same. All of those bk/wh leads are connected together. they should all read 12v ish. Including the ones that go to the ecm connector - although I have no idea how easy or difficult it is to probe those ecm terminals.

If any of those leads are dead then you have found the right area for your problem. Feed back - we can take it from there.

When you turn the kill switch off, they should all be dead.

I hope this does not sound as if I am being argumentative. I'm just trying to explain.
 
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Thanks again for your reply. I’m working on the bike as we speak.

I don’t want to argument in a negative way either. Please understand all is meant good. Let’s try to figure this out together.

The most strange thing is: I don’t have a ‘bank angle relay’… I have a lean angle sensor, but no relay for that (I figure a bank angle has something to do with leaning?).

I have: Screen relay(s), engine stop relay, power relay, fuel cut off relay, headlight relays, engine cooling fan relay. Therefore I also don’t have a purple black wire. In all the different official wiring diagrams (UK, US, Europe), there is nog ‘Bank relay’ nor a purply black wire… So I would love to do your test, but I simply can’t. I think the most logical is that your Bank relay would (kind of) be the engine stop relay. And the purple black would have to be the red yellow wire.

But, I will measure kind of the same, just with my common sense.

Going to continue to do some tests now! See full diagram attached.Wiring diagram kopiëren.jpg
 
First strange thing... The red/orange of the engine stop relay (which comes from the lean angle sensor) only gives me 0.60 orso volts...(when ignition on). Black white is ok...? The manual tells me, in the procedure to test the lean angle sensor, that there should be very few volts coming out of the red orange cable... So it does make a little sense. But according to your diagram, 12v should come out. Also at the other relays, that (place of) cable runs 12volts...
 
No.

I have oversimplified the diagram to show the lean angle sensor (= bank angle sensor) as a switch. It isn't a switch. I explain this over simplification in the text of the pdf file. It is an electronic device that has 3 wires input, one of which I believe is power.

So it does't ever show a direct connection to earth. Instead it shows a very low voltage. so looking at my diagram, the run stop switch and my incorrect bank angle sensor 'switch' will allow current to flow through the lean angle relay / bank angle relay turning the relay on.

In reality, the relay will have 12v applied at one side of the coil and 1v at the other end. That confused me for a while until I drew the diagram and realised that this still represents a potential difference of 11v - so while that sensor is showing a low voltage, the relay will still be turned on. If it showed 12v, then that would be 12v at both sides of the relay coil. No current flow. So the relay would not turn on. So in effect, the sensor is acting as a switch, but in reality it is a device that puts out 12v or 1v (0.6v).

I'll come back to you about the purple/ black lead - although you should be able to probe it from behind the fuse block. Take care, there are a lot of wires there that are always live.

I cannot remember where the bank angle sensor is located on the bike. Under the nose ?

All of the above is written from memory. I dont have access to anything but my ipad at the moment. But hopefully the gist is correct.


Bank Relay and Bank Sensor is how I have labelled the diagram. They are called the Bank Angle Sensor Relay and the Bank Angle Sensor in my documents, but Lean Angle is probably a better term. The bank angle sensor relay is grouped with all of the other relays with the fuse boxes behind the left hand side panel. A coloured diagram is shown on page 2 of the pdf file. You have access to the purple/ black lead from there. I put coloured paint spots on my relays when I created that diagram from the Honda original, so that I knew where to put them back.
I wasn't suggesting that you were being argumentative. I thought that it was my comments that might have come across like that !
 
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Hi John. Thanks for your reply. Please note: There is no bank relay (the one you drawn with the purple wire) on a ST 1300 (at least, not on the wiring diagrams of any kind, any year of Hayens). In my bike the wire colors match with the wiring diagram as I posted it. But don't worry, I call it the Engine stop relay (see in the middle of the pages I posted, next to the screen main relay) and it's in the same place as your picture. But, I have no purple wire. That wire is Red/orange I guess (see the scan of the diagram).

There is Bank angle sensor offcourse. That's the thing behind the screen in practice. And I did notice it in your drawing and yes, you left one wire out of that device in your drawing. The only strange thing that I found is that the red/yellow cable on my Engine Stop relay (as reference, probably purple in your bike) had no 12Volts coming in... That really bothers me. And I don't know if that is correct. I will tell you why: If I measure this terminal (where this cable goes in the relay) at any other relay, they all give 12Volts...?! So, is this my problem perhaps?

BTW: Found kind of the same topic/problem at this thread... Unfortunately the guy never gave an update what the real cause was... https://www.vfrdiscussion.com/index.php?/forums/topic/39715-bank-angle-sensor-question-pics-added/
 
Hang in, let me digest that and try to visualise it. I'll be back. Keep refreshing this page, I'll post additional info to this reply.

Yes. on the diagram above, what I have called the Bank Angle Sensor Relay or the Bank Relay, they call the Engine cut relay. Its the same thing. I used the terms from the Honda circuit diagram an manuals.

Your readings are ok. the relay coil has 12v going into it from the run stop switch at one end and a very low voltage from the lean angle sensor at the other end. So current will flow through the coils, so the relay should switch on.

Need to check next whether it IS switching on.

So the other two wires into the engine cut relay.
ppl/bk should show 12v always. if not, check your fuses (L ?)

bk/wh should show 12v when ignition is on and kill switch is set to run.
when kill switch is set to off, bk/wh should show nothing.
If not, I would pinch a headlight relay and use it instead of the engine cut relay. See if that works.
Flick kill switch on and off to verify relay is operating and bk/wh lead power is switched on and off.

Dont forget with all this testing, your headlights will be flattening your battery. It takes about 20 minutes, maybe less.


I'm off out for a while now
 
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Ok so here's the update. After this I have to leave aswell for a bit so will read comments later.

In the drawing below you find my reference. A 'curl' will mean everything is ok with all the measures. Notice on 'D' at the engine relay I measure some voltage as suggested to be ok.

You see that connection A on the fuel cut relay doesn't give me any current. This brown wire leads to the fuellpump and seems to be ok. The strange thing is, I read that if I connect bl/w (B or D) to A directly (with a jumpercable), the pump should work (with ignition on). But this test also didn't work. The wire is perfectly ok though and makes a solid loop with my multimeter. But maybe this test is no good. I also bypased the cable and jumped straight to the brown connector of the pump, but this also didn't work... Perhaps because my ECU is not connected...?

I am pretty lost now of ideas. Have to give this a place in my head. In the meantime I will await your responses.20220630_140214.jpg20220630_135643.jpg20220630_135637.jpg
 
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I need to write this down

Your Engine Relay or Engine Cut relay is the one that is triggered off by the kill switch and the bank angle sensor.

Power terminals
A Pk / Bk. 12v Ok
B Wh / Bk 12v Ok

Coil terminals

C Bk 12v Ok
D. Red Orange very low voltage

Comment. This is perfect. 12v is reaching one end of the coil via the black lead from the ignition and kill switch. The low voltage from the Bank Angle Sensor on the other end of the coil vis the red/orange lead allows the 12v current to flow through the coil ( nearly as good as being connected to earth). This created the magnetic field that makes the A and B terminal click together. The result is you have 12v going out on the white/black lead.

You don't say, but if you flick the run/stop switch off, the bk/wh lead will read zero.

No problems in any of the above.

Next Disgram. The Fuel Pump Relay or the fuel cut relay.

Power terminals
A. Brown. No output.
B. Bk / Wh 12v from the relay above, terminal B. Ok

Coil terminals

C Brn/ Bk. 12v
D Bk / Wh 12v ok

This is Ok ish. The Bk/wh lead has 12v going into the coil and the power terminals.
But the coil doesn't have any current flow. The only reason you can measure 12v is because you are providing a route to earth through your multimeter. Normally, the Blk/brn lead would be connected to earth by the ECM (but only for a couple of seconds after turning on the ignition). As soon as the bk/brn lead is connected to earth, the 12v on the other end of the coil will flow through the coil, create a magnetic field, turn on the relay, connect terminals A and B together and your fuel pump should spring into life.

Your Ecm isn't connected, so try it. Ignition on, a bit of stiff wire poked into C terminal and the other end placed on a good known earth point.
You will hear the relay click. If you don't check the earth point you are using, or carefully touch the negative post on the battery.
If it still doesn't click, you have a duff relay. Remove it, put it on one side and remove a headlight relay and use that in its place.

You should hear the fuel pump whirr when the relay clicks.

Connecting B or D to A should put power through to the pump without it bothering to turn the relay on. The fact that it doesn't suggests the the relay is not at fault, but it would be reassuring to hear or feel the relay click when the terminal C is connected to earth.

If you get the click don't get the fuel pump whirring then either the fuel pump has a fault or the connections to the fuel pump is faulty - brown lead, terminal A, or the connection to earth from the fuel pump is faulty. Trace the lead back and find the connector. Test the power for the live lead and the continuity to earth for the earth lead.
You can even try putting 12v into the pump directly at the connector, live and earth. Careful here the current is higher and may spark.

(All without the Ecm in place).

Its beginning to look like the fuel pump has failed, but I would want to check the wiring first. I think the fuel pump connector is tucked down the left side of the lower fuel tank, accessible from the left hand side, just below the seat tube. I think.

And of course you will want to know that the Ecu is correctly attempting to turn on the circuit to activate the fuel pump when you get it back. To do that, put your volt meter onto terminal C - the brown black lead. When you turn on the ignition with kill switch on, that should read zero and you should feel the relay click. After 2 secs or so, the relay will click off, and the meter will read 12v - because the Ecm is no longer connecting that lead to earth, and it still has 12v going into the coil.

You have leads, pieces of wire and a live battery. They dont mix well and could cause fire. Always put them down well away from your bike.
 
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Hi John. Yes, I can switch the black/white on/off with the kill switch. That works also. Tested it.

I always measure the 12V with one 'crocodile' of my multimeter on a ground/earth on the bike (the green wire actually of the fuel pump mounted on the top straight under the seat. That's nearby). And, I always test without the relay in. The relays are all ok. They all 'click' if I take them out and give them current the right way (Haynes explains these tests well). I also did the open/closed line test on the A and B terminals. Also passed the test. I could/will try the 'point C Black/Brown directly to earth' trick though (although, the ECM will come back tomorrow around noon).

I don't really get this part: "Connecting B or D to A should put power through to the pump without it bothering to turn the relay on. The fact that it doesn't suggests the the relay is not at fault, but it would be reassuring to hear or feel the relay click when the terminal C is connected to earth." This would be an interessting test I think... But I don't get it?

Just to be complete:
- De relay works (all of them actually). 100% Sure
- The brown wire from the relay connector which should lead to the connector of the fuelpump is 100% ok (not broken nor hotwired. Measured it 100 times)
- The fuellpump works (solo if you give it 12V). 100% Sure
- Brown wire (connector pin A) has no 12V. 100% sure...

Tomorrow around 11/12 o' clock I will continue the tests. First without the ECM after with the ECM.
 
Here is a thought, instead of testing for 12 volts with a multi meter try a 20 watt bulb as the meter does NOT put a load in the curcit. Just because the meter shows 12 volts it might not be capable of carrying a 10th of a watt.
 
Connecting B or D to A - was the suggestion that you had read somewhere. I was just checking out what that did and reporting back. This puts the 12v black and white power straight into the other arm of the relay that has the brown wire. This is the fuel cut relay or fuel pump relay. All it is doing is putting the power direct to the fuel pump from the black and white lead.

Unnecessary in my opinion. It is better to do the tests that I suggested with each relay in turn, then you know that the coils, the operation and the electrical switch all work before moving on to the next one in the sequence.

I would try earthing the fuel pump motor before you put in the ecu. Give that a test and see if the motor works. With what you have said, it should just spring into life - and it will stay on until you turn off the kill switch or ignition, or take away the earth connection - because there is no ecm to break the connection to earth. If it works but then fails when the ecu is installed it can only be the ecu or the earth cable / connectors to the ecu from the pump that are suspect.

I'm looking forward to reading the next bit, but I have an early start tomorrow and a long ride home. So it may be a while before I find out .

Good luck!
 
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Last question John, why would I want to earth the fuel pump extra as a check? It has it's earth on the top (de green wire) which I constantly use for all my measures. And, the pump works if I give it just 12V? Or, do you mean earth directly via the Brown/Black wire (C). I understood from my Dutch forum friends that this is the earth which is now not activated by the ECM? I was kind of suprised and I wonder, since that wire gives me 12V...
 
Excellent question. I haven't got a clue. I'm talking boll-twoddle !

My error. Trying to keep it all in my head and failing. It is the brown/black lead from the coil of the fuel cut relay that needs to be earthed to simulate what the ecm will do. As you correctly assumed.

If that wire gives you 12v, that is correct because the circuit is not yet completed. As soon as it is earthed, that will drop it to zero, current will flow through the coil, activate the relay and turn on the fuel pump motor. This is the one that you need to test when the ecm is in place in that first couple of seconds. When the ecm connects it to earth and the motor is switched on, it will read 0. When it disconnects it, it will read 12v. .... which sounds counter intuitive, but it is correct. I had to go out and test it when I wrote that pdf though, just to make sure that is what it did.

Sorry about that. I'm glad one of us is paying attention.
 
Another new update and super happy! So I know there is something wrong with the black/white wire. At the engine cut/stop relay this gives a neat 12V, but at the Fuel pump relay only 1.27V. That black and white wire really goes everywhere. So, I just started following that. There is a nice test plug in the back, that's where the black/white wire is too. Only 1.27V comes out of that too. I thought: 'If I feed it with the 12V from the black and white that does work (at the engine cut-off), what happens then? And sure enough, EVERYTHING WORKS! In itself I could drive like this, if I leave it this way. A very nice feeling. But, of course you want to know where something 'weird' is located, so that this wire somewhere suddenly no longer gets 12V... So, I'll search for a while, but in principle I can make things work like this.

Thus!

20220701_134930.jpg20220701_134941.jpg
 
This story is about to end with well... a somewhat happy ending...

It is unbelievable. So I started by opening the entire wiring harness to follow the black and white wire that does work (drama, I have to tape everything neatly again later). After all, somewhere the bl/wh wire splits to various other wires and there should be a break there was my reasoning. I stopped doing that because I simply couldn't get any further. I would have to lower the engine for full access. My only idea was: I'm going to make a permanent jumper loop in a proper way between the black/white wire of the engine cut relay and any other black/white wire. After all, that's how the bike would run. But, before I built it, I wanted to follow everything properly one more time. Again plugs loose / tight etc. Everything that has a black / white wire. Then, because I couldn't find anything I did the 'intervention' with the jumper loop between the permanent (good) black/white and the wire (doesn't matter which one, so took one) with 1.27V. Stuck a 15 AMP fuse in between for 'you never know'. This fuse can then be found with the other fuses. Engine starts beautifully. So I think: 'I'll take that fuse out' and guess what? Bike keeps running! So, of course, turned off the engine and tried again (without a fuse) and it still works?! Have I changed something somewhere? Improved something? Of course I've put contact spray everywhere, copper brush over everything and so on. But which connector was it? Or was it the wiring harness? And I'm not sure if it's a 'dangle' contact somewhere or a crimped wire. So I choose to leave the loop anyway. It is now 'both'. Even if it works without it. It's there anyway. This way I avoid suddenly stranding I think. But what the cause is will remain a mystery... Some kind of unsolved crime...

I have to be honest that I was already 'done' with the bike for some time. I am going to switch to a Moto Guzzi V 85 that I have had my eye on for some time. It was therefore extra frustrating that this had to happen right now. It took a total of 3 days and it is still not finished (everything has to be put together neatly). At the trade-in at the dealership I will tell that I this matter. And oh well, the engine now runs as it should. I'll put it back together tomorrow. Done with it for now.

What an adventure and thank you all for reading, thinking along and the support. Worth a lot!



20220701_181545.jpg
 
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Good stuff. That black wire originates after the engine cut relay and then supplies the power for all sorts of components. From memory (which may be wrong) these are the coils, the fuel injectors, the fuel pump, the ecm, PAIR valves, various engine sensors, ....
I thought that they were all connected together in on large terminal block, but I suppose they may have been spliced. It is probably just one bad joint - in which case feeding a good wire onto the bad end of another wire will sort out that issue, and still keep them all controlled by the kill switch and the engine cut relay (bank angle sensor relay).

Well done !
 
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Hi I'm new to here. I am trying to get a 2003 ST1300 running. It's a long story, but some of it is here:
I spent a lot of today determining that the relays upstream to the fuel cutoff relay are working, and the black/white is getting power. The relay bench tests as it should. I can jump the fuel pump directly (harness disconnected) and get it to whine. But when I power up, the brown/black wire shows 12v, there is not power switched to the brown, and there is nothing from the pump. Of course, the bike doesn't start. It appears the ECU is not connecting the ground as it should.
I don't own this bike, and the guy that does lives in Oregon, with a terminally ill wife and I was going to ride it to him.
Could there be something simple, like someone mentioned earlier that one needs to use a chip key? Is that true on 2003 models? The previous owner is dead- I picked it up not running from his widow, and seem to have all the parts. The key I'm using does have a Honda logo on it.
Also, when I got this bike it appeared to have no fuel. I put in about a gallon, and then the gauge showed 1/4. But-another mystery- now that I have jumped the fuel pump a few seconds, the low fuel light is now flashing.
EDIT:
The fuel level is back to 1/4, after the following. I used a 21W bulb to check for power at the 2 black/white. The bulb lit. Then I used it to check at the black/brown, that goes to the ECU, and showed 12V with the meter. The bulb did not light, but the connection to ground through the filament was enough to turn on the fuel pump. I tried starting when it was like this, but it did not fire.
I hope these clues mean something to someone.
EDIT2:
At least on the right side, there is no spark. So we have situation where the fuel cutoff relay is getting power via the black/white, but is not receiving a signal to close and power the pump, and there is no ignition either. What does this mean? I really can't afford to buy an ECU just on the chance it might be bad. If it is, fine, but they aren't cheap.
 
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I can't read the story on the advrider site because I don't have an account. Without knowing what is written there, my first question is- Are there any fault codes? If so, what are they?

My third question is- Did this motorcycle sit unused for any length of time? If it did, consider looking for damaged wires under the throttle bodies. These wires may have been chewed on by mice. If they have, one or more injector wires may be damaged rendering the injectors inoperative. If the injectors are inoperative, the ECM disables the fuel pump.
 
Quick reply.

The chipped key is only an issue if you have. bike fitted with HISS. Those letters will appear on the right hand side of the dash screen if you have it. I dont think that USA models have HISS fitted. It is an immobiliser system installed on European bikes and in some other countries.

The ecu completes the circuit to earth for only a couple of seconds after the ignition is turned on. it turns it off after that. If you turn on the ignition and then set up your meter or bulb, you will miss it .

Check - neutral switch, clutch switch, sidestand switch. The bike will not start in gear with the sidestand down, but it should start if it is in neutral.

Check the earth points. There are a bunch of wires meet the cross member across the frame behind the airbox, in front of the rider seat. The early models had problems with cables being rubbed and broken. I think that there is another earth point on the frame near the fuse box. Not sure about that. When you find them, take out the bolt, clean up the terminal and the frame. Resecure it.

I'll study your description and the diagram when I am at my PC.
 
OK. At the black/brown lead you will get 12v if the ecu is not completing the circuit to earth. ie the ecu is not completing the circuit.
As I said above, you have to measure this in the first couple of seconds after truning on the ignition.
If you get 0v at that bk/bn terminal, then the circuit is complete. It is showing 0v becasue the point where you are testing is connected to earth and it is after the only resistance in that circuit - the solenoid coil in the relay.

If you briefly connect that bk/bn lead to earth with the ignition on then the fule pump should spring into life.
You did that using the bulb in series, the the pump whined.

The fact that it is reading 12v and not 0v means that the ECU is not connecting it to earth, or you are not catching it in the first 2 seconds.

So either something else isn't allowing the ecu to complete the circuit
Either faulty earths
Or other sensor signals not allowing the ecu to turn it on.

Did you confirm that you bike does not have HISS ?

nb - if you have power on the bk/wh lead, then the fault is not at the run stop switch or the bank angle sensor or the relays.
 
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