Electrical questions for Ducati 888 build

cmd

Hi - hoping for a little help with my 888 rebuild noting that I did not take the bike apart and am/may be missing some bits!

My main issue is that the fuel pump does not prime when switching the ignition on and I have confirmed there is no power getting to the relay.

I am however missing the side stand switch wiring / relay and have an aftermarket regulator so I suspect that there is an inhibitor which is not switching the pump on.

By the thermostat housing I have a single green wire with a red tracer which is live with the ignition switched on and is terminated with a very small bullet type connector but is not plugged in to anything.

Just behind the left hand side of the fuel tank I also have a double blue wire and a yellow wire with green tracer, both unconnected. The yellow/green is the neutral light as if I connect power to the wire the neutral light comes on but obviously the switch goes to ground not a live.

Unfortunately I have not found a decent wiring diagram, the one in my PDF manual is un-readable when you try to zoom in so I am hoping that someone can give me some ideas where these wires should go and what I am missing. I would like if possible to bypass the side stand switch.

marvin

see if the one jimmy uploaded is any better

http://www.ducati851and888.com/showthread.php?8-888-Workshop-Manual

marvin

sidestand wiring

Your sidestand wiring is just for a light n the dash. Not an interlock.

hindsight

The fuel pump relay is controlled by the ECU, which switches it on once it has initialised. Suggest that you check the fuel pump relay by tracing out the relay coil connection and energising it by grounding it (pin #85 on the relay, I think). If the pump comes on, your ECU is not initialising - if not, then you've got a problem either with the fused relay, or the pump.

Mike

cmd

Thanks all. I have checked a better wiring diagram from Marvin on here and as you say the ecu suppliers both the power and trigger to the relay. I don't appear to be getting either which suggests the ecu is not sending the signal. I can get the pump to click using a power probe but I have no fuel in the tank so not sure if the power probe will supply enough current to run the pump. Is there anything else which the ecu needs to see to send a prime signal to the ecu and even without a prime should I not see at least the permanent live at the relay?

hindsight

The fuel pump relay signal is controlled by software in the ECU, and is only sent if the ECU has power itself, and has successfully initialised - so for example, if you have have power to the ECU, but an invalid EPROM installed, it will not initialise, and send the signal to the fuel pump.

I don't believe it depends on any other external signal to initialise, but I'd suggest that you check both fused relays (including the fuses in them) and ensure that you're seeing power on pin 20 of the ECU connector.

hindsight

Thinking about it - check your kill switch. That controls the ECU power, and has caught me out before.

cmd

Ok - getting a little further. Neither of the relays at the back of the bike have a permanent live fgoing to them only the switching live. That is the red wire going to pin 30 of each relay is dead. According to the 851 wiring diagram this should come directly from the battery but on my bike I only see 3 main wires going to battery +ive, one to the starter solenoid, one to the 30A fuse (which only seems to be used by the regulator which currently is wired directly to the battery and a 3rd to the fusebox.

The 851 diagram shows 2 wires from the battery side of the 30A fuse but my bike only has 1. I could really do with a complete wiring diagram for the 888 but the workshop manual doesn't appear to have a complete one unless I have missed it completely!

hindsight

cmd wroteOk - getting a little further. Neither of the relays at the back of the bike have a permanent live fgoing to them only the switching live. That is the red wire going to pin 30 of each relay is dead. According to the 851 wiring diagram this should come directly from the battery but on my bike I only see 3 main wires going to battery +ive, one to the starter solenoid, one to the 30A fuse (which only seems to be used by the regulator which currently is wired directly to the battery and a 3rd to the fusebox. The 851 diagram shows 2 wires from the battery side of the 30A fuse but my bike only has 1. I could really do with a complete wiring diagram for the 888 but the workshop manual doesn't appear to have a complete one unless I have missed it completely!

Yes, pin #30 on each of the relays should go directly to the battery positive terminal. See page 74 of the PDF that was linked to earlier in this thread. Also see the attached diagram, which is of a 916 Strada, but the loom is very similar.

I have a bike that uses a similar wiring scheme and that (red) wire is covered in black heatshrink, I recall once accidentally connecting it to the ground battery terminal and wondering why it wouldn't start. Could this be something similar?

916 Strada Wiring.pdf

500.01KB

marvin

cmd wroteOk - getting a little further. Neither of the relays at the back of the bike have a permanent live fgoing to them only the switching live. That is the red wire going to pin 30 of each relay is dead. According to the 851 wiring diagram this should come directly from the battery but on my bike I only see 3 main wires going to battery +ive, one to the starter solenoid, one to the 30A fuse (which only seems to be used by the regulator which currently is wired directly to the battery and a 3rd to the fusebox. The 851 diagram shows 2 wires from the battery side of the 30A fuse but my bike only has 1. I could really do with a complete wiring diagram for the 888 but the workshop manual doesn't appear to have a complete one unless I have missed it completely!

You only have one wire coming from the battery but it may be bridged somewhere in the wiring harness that you can't see. Check continuity and see if that isn't the case.

P.S. Another thing to remember: The ECU will only energize the fuel pump relay for a short while after the switch is turned on if the engine does not start. Personally I would try and connect the fuel pump directly to see if the pump indeed does function. If the polarity is reversed the pump will run backwards because it is a DC motor. Sometimes that works to "jump start" it if the pump has stalled or has a blockage. I would only run it for a very short while if it is not immersed because it will not cool.

erthmvr888

Make sure the ECU has a good ground - was my problem when i could not get the pump to energize on my bike.
Trav

cmd

Thanks all, the issue was as suggested, one of the black wires I had going to battery negative was actually red under the heat shrink. I now get the relays to energise although the pump itself still does not run. This may be the pump itself so need to check for power at the plug itself. Probably not wise to run the pump without fuel but will it harm it if it runs for like a second ?

marvin

Just hit it for a second or two and it will not hurt it. All you need to see is if it spins at all.

P.S. If it doesn't spin at all, reverse the polarity and it may break it loose if it's stuck

2nd P.S. Turn the stereo off and you will hear it if it runs 😄

cmd

Again my thanks to all, taken the fuel pump out and powered it up off the bike. It was stuck for a gentle tap has it spinning again. Reversed voltage and ran it again and then back to normal and now spinning nicely. Going to get some oil tomorrow and hopefully get it started for the first time in quite a few years... maybe back tomorrow for more help if it doesn't go! Still no neutral light but that can't be much.

marvin

Cool !! If it hasn't run for a few years the injectors are probably all crudded up. Put some fuel injector cleaner in the fuel and hopefully you won't have to remove them and have them cleaned.

hindsight

Well done, great to hear

cmd wroteStill no neutral light but that can’t be much.

I recall a 851 that I restored a few years ago, the neutral sensor was entirely absent and had been blanked off with a bolt. The neutral switch is a simple mechanism, so the fix will be similarly simple.