Newbie here.Very grateful for old post on ST1300 Fuel Pump circuit. The diagrams made my life easy for me.By a process of elimination found no continuity between Bank relay and fuel pump relay Not fancying digging into the loom i taped into the wiring with an auxiliary wiring set up and back in business.All is well so far.
No power to fuel pump relay
- Thread starter richie
- Start date
jfheath
John Heath
Glad it got you running again. But if you provided an always on 12v to your relay trigger coil, if you ever drop the bike, the engine will continue to run and will not cut out.
Also - I think that the engine kill switch may not cut the engine. Not sure about that without checking the diagram again.
Ever seen a dog chasing its own tail ?
Yell out if you want some more pointers.
Also - I think that the engine kill switch may not cut the engine. Not sure about that without checking the diagram again.
Ever seen a dog chasing its own tail ?
Yell out if you want some more pointers.
12V power is coming from bank relay,so kills power with ign switch and kill switch,as normal. Lean angle sensor...{Bank sensor] ...would cut power in event of tipping over.I had no continuity to fuel pump relay,so reason why i wired in a new connection between the two.Much better than digging into the loom.
jfheath
John Heath
Ok - so I guess that would be the b/w power lead between the two. And that is a good solution. There are a lot of those black/white leads providing power for various devices.
On 'later' ST1300s these are all connected together in a multiway connector - lots of wires going in - non coming out. A metal bus joins all of the wires together. Yellow, I used to think that it was behind the headlights. Edit : It is taped into the harness under the rear of the airbox, in front of the PAIR valve control solenoid. See the page here which shows a photo of the location.
https://www.st-owners.com/forums/threads/yellow-junction-box.188534/post-2538143
I believe that earlier models didn't have this, and that connections are made within the loom. (Again an assumption from circuit diagrams).
I don't know when 'earlier' or 'later' is or whether it only applies to the standard or luxury (abs) version. But if it has those yellow connectors, you could be seeing the start of a problem. If they get overloaded or corroded the terminal can get hot and melt the connector housing. Things like coils, injectors, various sensors all rely on the intergitty of that connector. They can get overlaoded if someone has added accessories and simply tapped into something nearby that is live. The total current passing through that connector shoots up and things get hot. (That's not the only cause though).
So if it is an early bike - you have probably found a perfectly good fix. If it is a later bike, you may want to go hunting for theis yellow connector just to check you don't have another issue waiting to bite you.
Someone else may be able to fill in the details with links to the yellow connector. In the meantime - its fixed and is working. Yeeehaah!
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Update.After two successful ,very short time start ups with fairings off, I reassembled fairings and lined up for the first test ride.Bike was unwilling to fire up and go through warm up process but did settle into an idle ....mmmm.... Rode bike through first and second gear,but entering a corner it cut out.It didnt want to fire up.I pushed it home.Fuel pump is working.Havent looked further yet,feeling a little miffed.THe fact the black/white power wire out of the engine cut out relay was live,but had no continuity to the fuel cut off relay is playing on my mind. I cant see the "metal bus" in my Haynes manual schematic diagram. I dont remember seeing one with the headlight removed.Thanks for your interest/feedback.
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My 06 st1300 Had same issue recently.Quit running 3 mi from home on 12-07-2024 Fixed it next day.Ran a bypass wire from another relay.Have since put 1000 mi on it since repair works fine!-I found in archive hear another guy who did same.did not see lump in harness where the bus connector is located (the actual burnt terminal)
I think the Yellow Joint Connector behind the headlamp is an earth/ground bus (helpfully not shown on wiring diagrams).
Ok - so I guess that would be the b/w power lead between the two. And that is a good solution. There are a lot of those black/white leads providing power for various devices.
On 'later' ST1300s these are all connected together in a multiway connector - lots of wires going in - non coming out. A metal bus joins all of the wires together. It is yellow or pink coloured and lives somewhere under the headlights. (Diagram says yellow - but I don't know that for a fact).
I believe that earlier models didn't have this, and that connections are made within the loom. (Again an assumption from circuit diagrams).
I don't know when 'earlier' or 'later' is or whether it only applies to the standard or luxury (abs) version. But if it has those yellow connectors, you could be seeing the start of a problem. If they get overloaded or corroded the terminal can get hot and melt the connector housing. Things like coils, injectors, various sensors all rely on the intergitty of that connector. They can get overlaoded if someone has added accessories and simply tapped into something nearby that is live. The total current passing through that connector shoots up and things get hot. (That's not the only cause though).
So if it is an early bike - you have probably found a perfectly good fix. If it is a later bike, you may want to go hunting for theis yellow connector just to check you don't have another issue waiting to bite you.
Someone else may be able to fill in the details with links to the yellow connector. In the meantime - its fixed and is working. Yeeehaah!
The Yellow power Joint Connector 1 (Black/White 12v wires) and purple Joint Connector 2 (Green, Green/Orange and Green/Black earth/ground wires) are located under the tank/PAIR valve.
Hope that helps.
aniwack
Site Supporter
The last one I had come through with the same problem was a bad ECU. Customer fixed himself by connecting the start/stop relay to the fuel pump relay so the kill switch would operate both.
Not encouraged but he couldn't afford the ECU markup on eBay.
Not encouraged but he couldn't afford the ECU markup on eBay.
Thanks,basically what I did...thought i fixed it....but it seems not.
jfheath
John Heath
For that circuit, the ECU simply provides a return to earth, that effectively switches on the circuit or not. Note that about 2 secs after turning on ignition, the fuel pump is turned off - which suggests that it isn't supposed to be on all if the time.
I have a theory about that yellow connector. Not proved.
Most of the black/white wires carry low current power to various devices.
They are all connected together. One (or more) of the leads will be the source of the power which is then distribute to the others
If someone at some time has found a convenient b/w lead (which isn't the one connected to the power source), and they have used it to power their own accessories, then that will increase the current passing through that connector. The bus bar connecting them together in the yellow connector will get hotter than it should as a result. One of the terminals will be hotter than the others. That will maybe the one with the worst connection - the one that has the highest resistance, or maybe the one that is less able to dissipate the heat. And that will be the one that melts, then moves and creates a worse connection, and arcs. Vicious circle.
That thought suggests the the location of the bad connection has nothing to do with the item that has failed. It still needs addressing, but the actual problem may be the set of headlights that were put on and connected to a b/w lead elsewhere.
Just a thought.
Does anyone know the circumstances that cause the ECU to turn off the fuel pump - other than 2 seconds after the ignition is turned on? The bank angle sensor does it by turning off the bank angle relay, so doesn't involve the ECU. I know that the 1100 has a SCR circuit which keeps turning on the SCR every revolution of the engine. So if the engine isn't turning, the SCR turns off. The ST1300 doesn't have this. Maybe the ECU turn it off if the engine isn't running. I think I have just answered my own question !
If so, by-passing the ECU in the fuel pump relay circuit could mean that if the engine stops - other than by tip over or kill switch, fuel would still be pumped. Where would it go ? Flood the engine. Or would it overload the fuel pump ?
I have a theory about that yellow connector. Not proved.
Most of the black/white wires carry low current power to various devices.
They are all connected together. One (or more) of the leads will be the source of the power which is then distribute to the others
If someone at some time has found a convenient b/w lead (which isn't the one connected to the power source), and they have used it to power their own accessories, then that will increase the current passing through that connector. The bus bar connecting them together in the yellow connector will get hotter than it should as a result. One of the terminals will be hotter than the others. That will maybe the one with the worst connection - the one that has the highest resistance, or maybe the one that is less able to dissipate the heat. And that will be the one that melts, then moves and creates a worse connection, and arcs. Vicious circle.
That thought suggests the the location of the bad connection has nothing to do with the item that has failed. It still needs addressing, but the actual problem may be the set of headlights that were put on and connected to a b/w lead elsewhere.
Just a thought.
Does anyone know the circumstances that cause the ECU to turn off the fuel pump - other than 2 seconds after the ignition is turned on? The bank angle sensor does it by turning off the bank angle relay, so doesn't involve the ECU. I know that the 1100 has a SCR circuit which keeps turning on the SCR every revolution of the engine. So if the engine isn't turning, the SCR turns off. The ST1300 doesn't have this. Maybe the ECU turn it off if the engine isn't running. I think I have just answered my own question !
If so, by-passing the ECU in the fuel pump relay circuit could mean that if the engine stops - other than by tip over or kill switch, fuel would still be pumped. Where would it go ? Flood the engine. Or would it overload the fuel pump ?
SCR = Silicon Controlled Rectifier. A diode which blocks current flow in both directions, but has an extra 'trigger' gate which if powered, allows it to 'turn on' and behave like a normal diode.
The SCR can be turned off by setting the input voltage to zero momentarily. The ST1100 uses a delay capacitor/resistor combination to 'slowly' drain the input voltage to zero, thus turning off the SCR - say within half a second. The ignition pulse to the coil turns on the SCR trigger gate every spark - turning the SCR on again. So it is being turned on much faster than the voltage can be reduced to zero - if the engine is running - so the fuel pump remains pumping. If the engine stops, the fuel stops pumping within that half second.
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Latest update. Cleaned up yellow wire terminus box again,cleaning out dielectric grease and used a good quality contact cleaner.With the Y piece bridge i spliced into the live wire out of the engine cut out relay and onto both black white wires into the fuel cut off relay there is now 3 sources of power into the yellow box.....that should help. Had a tech wizard over today who checked out crank angle sensor...ok..plus other things.It wasnt keen to start so he proceeded to wind it over with full throttle and then released the throttle grip.After the 3rd attempt it fired up. He then let it rev for 3 or so minutes,before letting it settle into an idle.Since then it has started and run normally. He said it was basically flooded,and by giving it full throttle it allowed the ECM to turn of the injectors and thus clear out the system.I have replaced the spark plugs,oil and oil filter in case of contamination.All a bit of a head spin but its looking good and running well.Many thanks for the feed back and a big thumbs up for a great site..It must be beer o clock !