C41 fault on K5 DL650

[DrawingBusiness]

Hi all,

On the way home from work a few weeks ago, my K5 DL650 died. It refused to start, and was a displaying an FI indicator and a flashing red light on the instruments. I had an instance in previous weeks of an FI indicator coming on, but the bike went into “safe mode”, so I could get it home. The problem seemed to appear after spraying ACF50 up onto the throttles; after removing the airbox, and cleaning all the injector and sensor connectors with WD40 Contact Cleaner, the bike seemed to be running fine again. Until it stopped completely when I was accelerating quite hard.

After getting the bike trailered home by my friendly neighbourhood AA driver, I used a jumper cable to put the bike into Dealer Mode, and got the C41 “Fuel Pump Relay Circuit Malfunction” error from it. I took the fuel pump relay off, and tested it with a 9V battery and a multimeter; the relay is fine. I assumed that the fuel pump had died, as I couldn’t find any other faults, but when I took the pump out and applied a 9V battery to it, it spins fine. When I plugged the pump back into the bike, I still had the same C41 fault, and no movement from the pump.

Stepping through the suggested tests in the service manual, I took the airbox off again, and checked the injector connections. Both injectors are getting power, and there seem to be no continuity issues with the injector wiring.

My next step was to try and eliminate a fault in the ECM, so I took pin 32 out of the ECM connecter and used the test method for determining the fuel pump output: apply the pin directly to the battery with the ignition on. Again, no action from the fuel pump.

I’ve done some other checks, and when I turn the ignition on, the orange/white on the fuel pump connector is getting 11 volts during start-up. The black/white wire has a path to earth (I get a current on the multimeter when I connect from the black/white terminal connector to the negative terminal on the battery). I’ve looked at the wiring diagram, but my electrical skills aren’t good enough to decide if that wire should have a path to earth or not (it's been a steep learning curve already trying to get the hang of using a multimeter, something I've owned for years but never used). I assume the power has to go somewhere?

So, as far as I can determine, the FP replay is fine, the ECM seems to be okay, and the fuel pump, which runs fine when a voltage is applied directly to it, is getting sufficient power when I turn the ignition on. But it’s not spinning, and I still get the C41 fault as soon as the bike has completed its 3 second start-up sequence.

Does anyone have any ideas what the fault might be, or what I should look at next to try and track it down?

Thanks,

Richard

[Mojo-Jojo]

Check all of the plugs under the air box/behind the radiator. On my K6 all these connections were corroded, and were causing F1 not staring issue, and headlights failing. It took approximately 6 hours to clean every single connection and cover with inner tubes, but I've not had a single fault since.

[Gert]

Perhaps a refresh on the multimeter may be in order, see Using a Multimeter guide in http://www.ldriders.com/using-a-multimeter.html.

Personally, I prefer to use an automotive headlamp bulb as a test lamp. A multimeter is sometimes too sensitive and can often pick up a stray signal from another source thus giving a false reading or in my case confuse me.  To make your own test lamp is easy. Solder two longish (2 - 3 foot) leads to the bulb. One lead to the casing, the other lead to either the bulb high or low lug at the base of the bulb.  Connect the one side to the battery positive and the other is now your test probe looking for a negative. If looking for a positive, move the battery connection to the battery negative. Primitive but effective.

Looking at the diagram in section 4-13 of the K4 650 manual, does the fuel relay click when you turn on the ignition - aka fuel pump prime?  Is there any means that you can use to test to confirm whether the relay contact is closing to complete the fuel pump circuit?

[DrawingBusiness]

Yes, the relay clicks when I turn the ignition on. I've tested it off the bike too: no circuit across the fuel pump connections when 'inactive', and a circuit when a voltage is applied to the solenoid. As mentioned, I've tested the power to the fuel pump connector when I turn the ignition on: I get 11 volts (battery voltage) when I turn the ignition on for 3 seconds, until the relay switches off again (the ECM waits for the "engine running" signal before switching the fuel pump back on). I'm very confused as to why the fuel pump spins when I power it directly, but doesn't spin when attached to the bike, even though it's getting power.

[Barbel Mick]

When you say "11 volts (battery voltage)" is that directly across the battery terminals? If so that would be too low to start the bike, I would be looking for 12.5 volts at least, a fully charged battery would be 12.8 volts.
It may be enough to operate the fuel pump but when you put the bike under load by trying to start it the voltage will drop even lower.
Put the battery on charge overnight and try it.
 

[TLPower]

My initial thought was the tip-over sensor.

https://www.stromtrooper.com/threads/tip-over-sensor.30361/

[kwackboy]

As mentioned above.

Check  all the switch gear connections that are fixed to rear of the radiator, they are more than  likely corroded.

Especially the kill switch side ...

Suzuki are well known for this issue , not just on vstroms ...

[DrawingBusiness]

@Barbel Mick: No, the 11 volts is on the orange/white wire of the fuel pump connector; the battery voltage is >12 volts.

[Brockett]

I would still sugest you recharge the battery and then examine every connector under the tank and every inch of the wiring loom to check there are no shorts to earth going on. Plenty of horror stories on here with corroded plugs and sockets and frayed wiring to give us all nightmares.

[Barbel Mick]

How much greater than 12 volts?
Without looking at the wiring diagram to see if the fuel pump circuit has resistors in it, why is it only 11 volts at the pump, is that what it should be? Maybe it is a high resistance connection somewhere that is causing it to lose a volt?
As I said earlier charge the battery overnight then let it stand for a few hours and take a reading across the terminals, it should be 12.8 volts or very, very close to it. Then, as Brocket & others have said check as many connecting plugs as you can find for corrosion or burnt/dirty contacts.

[DrawingBusiness]

Thanks for all the tips. I think I'll definitely start with the connectors above the radiator. They were a bit of a mess when I took the airbox off, but I didn't touch them because I didn't think they were involved in the fuel pump circuit. Luckily I cleaned up all the airbox fasteners and connectors last time I took it off, so getting it off again will be hassle free. I had begun working my way along the main loom, forward from the fuel pump connector, but so far haven't done more than unwrap some of the loose bits of loom tap to see if there is a big hole in one of the wires that would be an obvious contender. When I checked the wiring diagram, the black/white wire from the fuel pump connector (which my multimeter says is connected to earth, but I still don't know if it should be) goes up to the instruments, so I was following it looking for anything suspicious. But eliminating a bad connection above the radiator seems like a sensible first step.

That's assuming I can stop tinkering with my new bike long enough to try and fix the old one. So far, fitting accessories to the 1050 is winning out. 

[Gert]

Looking at the wiring diagram, the injectors along with their respective connectors are part of the fuel pump circuit. I'm looking at the Y/R lead on the fuel pump. The B/W lead is the common negative / ground / earth from the battery to various other components.  The Y/B lead goes to the fuel gauge along with the B/W common feed.

[Gert]

 Since the fuel pump was tested and runs with a 9 volt supply, then I would think that 11 volts should in theory then allow the pump to run while submersed. I wonder whether the power is actually reaching the fuel pump inside the tank.
 Have you perhaps checked whether the fuel pump connector is actually making a good connection? It is possible that one of the pins in the connector could be loose and not making enough contact to provide power to the pump.

[DrawingBusiness]

Yes, my next move is going to be applying power from the battery directly to the fuel pump terminals. When I tested the pump out of the tank, I did it by applying a battery to the connector terminals, which implies that the connections are okay, but it could be an intermittent break. Thank you for confirming that the b/w wire is a common negative; I had a feeling that was the case, but as I said in my OP, my understanding of electrics and wiring diagrams is pretty minimal (although I'm learning through necessity).

[purplebikeunicorn]

If you haven't already, give all these wires a tug. A tug from connectors (to identify pins not quite being held in properly), and a tug along the wire, to identify where wires may be broken inside the insulation. Bubbled/swollen insulation may be a big giveaway if some corrosion has started on the wire itself.

Although the pump ran, was this submersed in liquid or in a pressurised system? If the motor is kaput, it may run with no load, but the moment any kind of load happens (in liquid, or when the pressure increases on the fuel system) it goes wacky.

[Gert]

Any progress / solution yet? I'm curious to hear what caused the fault.

[DrawingBusiness]

Still no solution yet, but at the moment most of the harness connectors are still unplugged after cleaning. I haven’t had much time to sink into getting it all back together.

[Gert]

Please report back with any news / progress on solving this fault.