Hi Guys,
New guy here and pretty new to ducs also. Finally got on this site and really glad to see it back online. I've kind of gone crazy the last few months after selling almost all my old BMW's over the last couple of years and thinking I was through buying cycles and then the ducati bug bit! I've got 3 907's now, 2 really nice ones and one that looks like a escapee from a chop shop. Iwas trying to get the fuel pump to run today but no action when using the key. The pump will run when power is applied straight from the battery. I switched relays around but nothing. It just seems power is not getting to the pump. I also noticed that engine will turn over regardless of where the kill switch is moved to. So what and how do I check now? I've donre some searching but nothing. Oh, this is the bike that going to need a resto and will be my learning platform for ducati's. Thanks for any help. Arch.

Hi Arch.

3 * 907's must be a bit of a record!

The fuel pump only gets power when the Kill Switch is in the on position. Remove the RHS side cover, and at the back of the tank is a 4 pin plug and socket. This is where the power for the fuel pump goes through to get to the pump, and the connection for the fuel gauge. Unplug the Plug/Socket and use a Multimeter to probe the 4 connections until you pick up 12 volts (assuming the kill switch is in "Run"). It should be the violet wire if it is visible. If you find 12 volts, turn the kill switch to off and see if it disappears. If all good, then the issue is between the the plug and the tank (ie: wires, connections etc). If no 12 volts, then most likely the wiring to the relay or the relay is shot. Out of curiosity, do the 2 relays (up near the regulator, LHS behind fairing) have fuses incorporated in them? It may just be a blown fuse (or 2)?

There is colour schematic in the documents which will help.

The engine will crank in any of the 3 kill switch positions, but will only start in the Run position.

Cheers.

Nick.

The other possibility is you have no ground. The circuit is grounded by the ecm which has a diode that is easily repaired. So if you find both relays do have power but you still have no fuel pump you will need to replace the diode assuming all the wiring and relays check out OK

-

Thanks for the replies guys and the attachment. Electricity was never my thing but better start learning! I'll be going out to where I keep the bike and check the power supply and the fuses are good on the relays. This bike has been lowered with wild graphics on the sides and generally unloved but will get it back to its former glory! Thinking about repainting it in black or maybe even dark green. Thanks Arch.

The other 2 907's are a bonus when fault finding , it is very helpful to have another working bike to compare test results , and to switch parts over to prove a fault. I think I would be happier to have 2 good bikes and one pile of parts
Hamish

Well I did some more fault finding today and as suggested checked the plug that fits onto the pigtail from the tank and did not get any power going to the violent wire, only the blue wire showed any power going to it.
also checked the prongs where the relays plug in and only had power on one and believe that was no. 30.
This bike is a 91 and my other two are 93's and they will not turn the eng. over with kill switch off but the 91 will turn the eng over in off or on. Guess I will pull the relay receptacle off and start testing that. Any other suggestions? Thanks for the help, Arch.

If you have power to one you must have power to the other, its a short wire jumps between the two and very unlikely to be the problem. Could possible be the relay which most often is the fuse part of these kind of relays, but you already said you switched the relays so.............
sounds like you have no ground on the fuel pump relay which means you need to trace the ground back to the ecm

my money is on a popped diode at the ecu ground which is a simple thing to verify. Just ground the wire at the ecu connecter, if the pump runs the diode is blown in which case you have 2 choices. Put the fuel pump ecu ground wire on a switch to ground or solder in a new diode in the ecu

the blue wire you mentioned goes to the fuel sensor so that´s irrelevant.
Contact #30 on the relays is the main feed which is connected directly to the battery (see diagram above)

Did you check if all fuses are ok and if you get 12V on the grey wire connecting to one of the relays (when the kill switch is in RUN position and the ignition switch is turned to ON) ?
One relay switches on the Marelli Digiplex unit which then activates the second relay powering the fuel pump which means that when the ignition is turned ON (kill switch on RUN of course) you should measure also 12V on the white wire going to contact 85. (the upper relay in the diagram above)
If there is it can only be a ground connection problem as higgy says. (unless the relay itself has gone south but you can test that)

G.

OK, went out today and pull relays out of one of my good bikes and still no power to fuel pump. While tugging on wires here and there I discovered a red wire going to postive post on batt wasn't even connected! It was hidden under the rubber boot on postive post so didn't notice it. Still no power to violent wire in plug but now have power to both no. 30's 0n relay base. Tomorrow I'm going to connect up a new ecu that I picked up to eliminate possible ecu ground problem as Higgy has put forth. The wiring on this bike has been dicked around with so who knows what has been done to it. I keep telling myself this is supposed to be fun and it is in a way. Oh well, at 70 years old at least it keeps my brain whirring. Thanks for the help, Archie.

never mind but a bit more methodical approach is always better (what about all fuses?)
If the wiring is messed up and you just swap parts in worst case you`ll ruin your new ECU. In best case it will work but you may still not know what the actual problem was.

(How did the engine turn over if the red wire wasn`t connected to the battery ?)

G.

Hi G.
This appeared to be another red wire that had been connected to Batt. I just checked my new ecu for grins and there was no chip in it and it was supposed to be for a 92 907ie! The anti tamper red paint was missing so someone has been in there already so a blistering email has already been sent and now waiting to hear Arch.

Morning Arch.

How badly butchered is the wiring harness? If its cut to shreds and wires twitched back together, it might be wise to bin it and get a new one. There was a complete new one on eBay a while back in the US. I think I popped the link in the For Sale section here? It might save a lot of headaches down the track.

Cheers.

Nick.

I have a standard 907 chip I can send along if you need it...........