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Fuel Line Issue 748

1831 Views 11 Replies 4 Participants Last post by  ReUhssurance
Hello all, been a long time lurker and have done quite a bit of research and am somewhat at my wit's end with this problem of mine.

I have a 2000 748 and it's fuel lines are not prepping when I pop up the kick stand and flip the kill switch on. The engine does turn over (sounds like it's about to fire up, hear/see the clutch assembly ringing/spinning a bit). But it does not catch and actually start. Like I said, when I flip all switches on, normally I hear the fuel lines prep but it is no longer the case.

I've been researching this quite a bit and decided to buy a new fuel pump (gold cylindrical piece in the fuel pump assembly) and have replaced that and have the same issue. I inspected the low level fuel sensor wiring and visually appears to be okay, but I do not have a multimeter or much electrical know how to be able to test. I have also replaced the two fuse pieces underneath the seat at another recommendation I have seen floating around.

It may be worth noting that I purchased a new battery from autozone earlier this season, it is not the exact sizing but it started everything up fine for a couple weeks. The lights on the dash and headlights come up fine when I turn the key on still as well. Seems like all electrical is okay..

So my question is, does anyone have any recommendation on what my next course of action should be? I'm pretty antsy to get this thing back up and running as I've been missing the best time of year to ride. I'm considering calling Ducati and seeing if I can just bring the gas tank in and have them inspect the fuel pump assembly for me, but am also concerned about getting charged to all hell.
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did you replace the pump already? if so is it new or tested working used? it could be lots of things, check the fuses, there are relays under the seat that control the pump (will have to research what one), split fuel lines in the tank, fuel filter clogged, wiring problem (check connector under the tank), side stand switch bad, bad kill switch, other things as well but those are the most common ones. if it was running one day wasnt, i would check the easy things like fuses, relay and especially the side stand switch (is one of the most common problems), most people bypass the switch but that isnt a good thing to do, bike can start in gear or with the stand down (not a good thing there).
go to ducati.ms and look under the hall of wisdom for lots of info on this and many other problems.
I appreciate your response. And no I don't have the equipoment to test the fuel pump properly, it was a new one off ebay.

As for the side stand switch, the funny thing is, I can hear a little switch sound like it turn on and off when I have the kickstand up and turn the kill switch on. It basically has the same timing as the fuel line prep did but just sounds like a little light switching on and off almost underneath/behind the seat somewhere.. So I'm kind of hesitant to think it's the kickstand (already went through my head, and besides the bike wouldn't actually start with the kickstand right? I mean when I fire the ignition switch I wouldn't be hearing the engine try to turn over?)
Are you using a battery tender? I had a very similar issue happen to my 996, i had believed it was a weak battery but if you have a tender wire on your battery and its plug end is not covered /capped when not in use you may be discharging your battery, causing a weak battery issue. if this is the case, all your lighting will turn on when you go to start it and the bike will try to turn over ( you can hear the fuel pump prime and the clutch will spin a little)
I have had a quick disconnect wire on my battery and no I don't believe it was capped. But this is still rather strange because you said you could hear the fuel pump prime? I don't feel like I hear anything from my fuel pump even when hitting the ignition. But like I said, I do feel like I hear an electrical signal clicking with the same timing as said fuel line prep.. Hmm, I will try hooking my tender back up to it this evening after I get off work for the night. I did this the first night it happened and didn't get anywhere but who knows, worth a shot.
to hear the pump you may have to put your ear on the tank. or you could open the cap and listen while you turn on the key. start checking the small stuff, relays fuse, kill switch, ect.
Alright, reporting back. Hooked it up to the charger during my lunch today, came back, same issue. I even have a known working battery on another bike that I hooked it up to and had the same bit. I can hear the engine catch just a little sometimes and then die (presumably because there's no fuel being delivered to it), while other times no, it's just a bit iffy.
Also tried putting my ear up to my tank like you said, and heard nothing. I'm still convinced it may be that piece (low level fuel sensor?) I don't know, I was able to visually inspect it and it seemed okay. Problem is that wire goes into the side of it and seems like there's some sealant poured around it and hardened or something (didn't want to bust whatever the gray stuff was).
time to start trouble shooting, down load a manual
The fuel pump is controlled by the engine management computer. When you hit the run switch, the computer powers a solenoid under the seat that sends power to the fuel pump and turns it on. The computer then checks the crank rotation sensor to see if the engine is running — if not, the computer cuts power to the solenoid after about five seconds which then shuts off the pump.

First check if the pump works by running two wires from the battery to the in-line connector to the pump located under the tank. If the pump runs then check that the solenoid is working. Raise the seat and listen for a click when you hit the run button. You should hear a second click a few seconds later.

If there’s no clicks, you likely have a bad solenoid. Replace it.

You should first check if the computer is sending 12 volts to the solenoid using a multimeter. If not, the problem is with the computer.

(The fuel pump supplies fuel under pressure as long as the crankshaft is turning, i.e., the pump is switched off by the ECU if the crankshaft stops turning as a safety feature to help avoid fires following an accident).
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Wow thank you for the write up and explanation.

To start, I do hear the click when I hit the run button, and the click a few seconds later that you mentioned. Reading that, that is exactly what I have been trying to explain when I say that it sounds like it's trying to start but doesn't. This makes sense now. I do have a few questions to follow up before I hack things up..

You said to troubleshoot the pump, I can run two wires from the battery to the inline connector on the pump. This inline connector you speak of.. Is it the piece on the left of this picture? If so, do I just take one wire from positive and one from negative on battery and touch all of the (I believe it's like 3 metal teeth inside that connector)? If that's the case I should just touch the two wire/plates that I rig on the connector and should (should in theory) hear the pump start, if it does not then I can tell that that connection would be the issue correct?

Also, unfortunately, I do not have a multimeter. I wonder if Home Depot can rent one out or something now that I think about it.
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So I just wanted to follow up with everyone, thank you for the advice.

Bike is up and running now. After I replaced the pump itself as previously mentioned, I still had the same result. I ended up taking the battery off and charging it, tried a battery from another bike and had the same result.

So it's been almost 2 weeks that I haven't had time to do anything with this due to other obligations, but tonight I hooked my battery back up, flip the switch and sure enough I hear the line prepping. Bizarre! But at least I know the pump is functional, took the bike out for a ride and everything fine, just need get my rear brake back up now. Not entirely sure what I did that fixed it at this point, wish I had a better idea but I'm happy that it's up and running at least.
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