Ducati Monster Forum

Need help sorting out a fuel pump issue.

Found and replaced a dirty fuel filter in November.  Bike ran fine afterwards.
A week ago, when you turn the key the fuel pump does not prime, but you can hear the relay click.  I get power to the harness at the fuel pump.  I take apart the pump, cannot find any bad wires, jump power straight to the pump and it turns over.  I realize that I'm running the original batter on an 05 620, so I put in a new battery and the pump primed, and the bike started right up.

Next time I ride it cuts out after 40 minutes, now doing the same thing:  no prime, no start.  Gauges sweep, relay clicks and you can measure power at the fuel pump harness.  Troubleshooting leads me to believe the pump has failed.  (put on Ted's (artful's) tank and bike started right up, ran up to temperature)
I replaced the fuel pump via CA-Cycleworks and at first got the same result.  Took the pump apart and put it back together and the bike primed and started right up and got me home from Ted's, about a 30 minute ride.  This morning on my way to work, bike cut out again, now same thing, no prime, no start.

I checked the charging system when the bike was running and it checks out OK, 14.47 volts.

I'm going to hunt for a bad wire (even though that has already been done once) but otherwise I'm:
Stumped, please help!

Thanks,
Matt

I have a similar problem to this, but acquired by different means. 

I bought a salvage bike that ran fine, the took it apart to have the motor mount welded.  When I
put it back together, this happened.  I put the key in, turn it on, and immediately a clicking starts
(fairly rapid, not too loud) and, after lifting the tank up and listening, have determined it to be
coming from the fuel pump itself.  Unplugging the fuel pump confirms this.  I thought maybe I had
hooked the fuel lines up backwards when I put the tank back on, but reversing them didn't help. 

If there is anything that I can cross-check to help find the cause of the problem, please let me know. 

Also, if you are having a completely different problem and I'm just junking up your thread, let me know  ;)

Uberranger, the problem you had is different.
Thanks though!

Okay, good thing I checked then!  :P

Good luck

There have been a few threads about the wiring failing inside the sending units.

so here's my stupid question:  what exactly is the sending unit?  I've read some of these threads and didn't catch exactly how to check it out.

Is it the device that mounts on the flange at the fuel inlet?  If not, what the heck is this thing?  This has only the black wire running to it, coming from the plug for the fuel pump motor.  I don't know what this is.  I know what everything else is, there's a resistor to signal low fuel, the pump, the filter, and this little device at the inlet????

What is this device's purpose?  My tech guide does not really break the fuel pump completely down.

The sending unit is the part that triggers the low fuel light when the tank is low.  What year is your bike?  Plastic or steel tank?

2005, plastic tank.

Sending unit is not sold seperately from the fuel pump/flange assembly.

Thanks for the info Speeddog, the manual does not list the part number for this and it looks like you might be associated with a dealer, do you know the part number?  Does the flange include the pump motor, because I'd kind of hate to buy two in a week....

There is a part number listed for the thermistor, with the black and white wire going to it.  I've been trying to find out what ohm reading I should get on this and can't find it on any of the other posts.  Any detailed advice on how to test this out and figure out exactly what to buy would be great.

Thanks again everyone for you help.  I hope to have this sorted out soon, I haven't had a reliable bike since November and at this point I'm really ready to hit some twisties!
Matt

http://www.flickr.com/photos/80693452@N07/?uploaded=1&magic_cookie=3cf265f9aca4da88b79a8c07604e8ab8 (http://www.flickr.com/photos/80693452@N07/?uploaded=1&magic_cookie=3cf265f9aca4da88b79a8c07604e8ab8)

This is the part with the black wire running to it that I describe in the original post.  Ducpainter tells me he thinks it is the pressure regulator and not the problem....

Just trying to get a better understanding of the overall system and the components.  Thanks!

The parts catalogue shows it as 160.2.135.1A Flange, includes pump, filter, thermistor, everything.

Downside is it's *extremely* expensive, ~$1k.

Fixed your pic:

(http://farm8.staticflickr.com/7241/7398312968_d42251d53a.jpg) (http://www.flickr.com/photos/80693452@N07/7398312968/)
Pump Component (http://www.flickr.com/photos/80693452@N07/7398312968/#) by Blackboar19 (http://www.flickr.com/people/80693452@N07/), on Flickr

Can anyone tell me how many Ohm's I should be reading across the thermistor?  I'm getting 3.3.

I also think I'm finding a bad wire connection inside the plug to the pump motor, I'm going to fix that up and see what happens.  I'm getting intermittent continuity when I test the black wire, and the culprit seems to be the plug.  I'll keep you all posted, and thanks again for the help.

UPDATE:  FIXED !! 

It was NOT the sending unit (thermistor) as thought.  It turns out that the black wire running to the pump motor was broken right at the potting passing through the flange.  The insulation was totally intact but the wire inside was broken.  This is the wire which was in question but kept giving me good continuity, so the last time I rebuilt the pump it was making contact, but on the ride would come loose.  I took a friends advice, cut the wire on both sides, drilled a hole through the potting and pulled a new wire sealing it up with some JB Weld.  I also replaced the harness on the pump so that I only had one splice at the harness OUTSIDE the tank.

Since nobody can tell me the resistance on the thermistor, I'm going to go with my reading of 3.3 ohms and say that is normal.

We are working on a solution for replacing the wiring in flanges. This is becoming very common on plastic-tank'd monsters. We're getting calls from people with < 3 years old and under 10k miles. We're trying to get the parts made in the USA and hoping I don't regret it... (I think if it was being made in China, we'd have product on shelf already)

Chris, a replacement harness would be great.  It's a shame that Ducati does not make this part available as it is SUPER EASY to pull off one retaining clip and slide the whole harness out.

Fixed is sometimes a loose term, as it turns out, JB weld did not hold up to being submerged in gasoline.  I'm trying out a potting compound from 3M now that should do the trick, but it's not fully cured yet so I won't know for another day.

Hey I have a similar issue where sometime my bike does not start. It seems to be as if the pump is not priming. But now my main difference is that the bike has not shut off on me once running. Also sometimes if I just leave the bike and go back to it, it will fire on the first crank. Do you thinks I may have the same issue?

I have this exact problem on my 620.  If you don't mind, can you answer:

How did you replace the harness on the pump?  Is this a part you ordered somewhere, or were you able to remove and re-seat it?  I'll need to run a new wire and I do NOT want to splice inside the tank, obviously.

Thanks!

Oooo, I forgot about this thread and just was reminded of it via PMs.

Update: the Made in USA people were 5 times more costly than having the parts made in China. :P So they're being made in China. I'm on the 2nd sample and the oring grooves are still too deep... iteration 3 should be the charm.

For those attempting a repair:
I've suggested this to a couple mechanics: you can re-purpose wires for a temporary fix. There are normally 4 wires, (+)(-) for fuel pump and (+)(-) for the fuel level sender. You can combine the (-) leads together and then re-locate the "spare" (-) lead on both sides to work on the (+) for the pump.

Or using eyelets, ground the (-) connections to the flange itself on either side, freeing up those 2 conductors for use on the pump(+) and the fuel sender(+).

The way to construct fuel tank passthroughs is to have the wires soldered to posts in the middle of the plug. Then fill the plug with gasoline resistant epoxy. This is what eliminates the hope of a repair; the epoxy is too aggro. I suspect that the wire break is on the outside of the plug where the wires are soldered to the pins or where the wires enter into the epoxy.

To try and improve the design, I have changed a few aspects of the design... I'm basically having 1098 fuel pump wires being made and then adapt those to work in the larger openings on the Monsters.

No word about an ETA for these. Each rev takes a couple weeks then once we get everything sorted, it'll be a couple weeks for the production run. So by year's end, I'd say. It'll be in the 2013 catalog, for sure.

Thanks,
Chris

Alright, I so I dug out the epoxy from the inside-the-tank side of the assembly, and 3 of the 4 wires just fell loosely out.  I'm ready to re-solder, but I have one last question: when I'm soldering, should I put the wire in the hole and then solder around the edge, or should I put some solder on the wired and then hurry up and shove it into the hole?  Or is there a third method I haven't considered?

Thanks.

Also, to David:

There are a few things that could cause what you're describing.  The quickest way to test this is: when it's failing to start, check that you're getting power to the harness that goes into the tank when you turn the key.  The fuel fump power will kick on for a second and then kick back off when you turn the key to "on".  If you're getting power all the way up that point, but the pump is not priming (you should hear it fire up when you turn key to "on"), then you either have this issue or a bad fuel pump.

Hmmm, I suspect that when the wires were soldered, one side got hot enough for the OTHER to melt the solder. :( I would tin the wire with solder first. Then heat the socket until the wire will go in and immediately remove the iron from the socket / pin.

 iltl32
when you dug out the old epoxy was it mushy or still solid?
I think whats happening is the ethanol in the fuel we buy is leaching through an incompatible epoxy that ducati uses.
when the ethanol reaches the electrical connection it eats away at the solder joint leaving it brittle and prone to cracking.
Solder is made up of a tin/lead alloy and is NOT chemically resistive to ethanol.
I think the key to a perfect repair is to make sure the epoxy we are using is truly compatible to our fuels.
I used jb weld pro and i will wait until ~January before opening it up to check how well its holding up.

chris
your soldering technique is spot on. I have an electronic background with 30yrs as a process control tech and i've always soldered using this technique. good recommendation chris

I would not say it was mushy.  It was flexible, but still very firm.  Kind of like digging at a big pencil eraser.  I used a tiny drill bit and a dentist's hook to remove it all while leaving the wires intact.  I'm not sure if it's supposed to be that way or if it should be rock-solid.

Anyway, most of it is out now.  I got some J.B. Water Weld, which is supposed to fuel-resistant.  I'm going to solder everything back up on Wednesday and I'll post the results here just for the record's sake.

its supposed to be hard like the epoxy on the outside of the flange.
There is another epoxy available from Permatex, # 12020. I haven't used it but its supposed to be gasoline submersible.

Re-soldered wires and re-sealed with the J-B Water Weld.  Hooked it back up (not inside the tank, just sat it on the seat) while waiting for the epoxy to dry, turned the key, and the pump primed up like it's supposed to.  Everything looks good.  Thanks to everyone for their time and help on this, I definitely would never have been able to figure it out by my newb self.