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Discussion Starter #1 (Edited)
I THINK what I have is a ruptured line inside the tank. Bike worked fine the day before. But yesterday when I went to fire it up, it just cranked and I got an occasional backfire.
When I looked in the tank while cranking, I see a stream of fuel trickling down inside the tank. Can't be normal.
Am I thinking right here? The famed inside tank hose(s) are ruptured?
Guess I need to call DesmoTimes and get some line, a filter (or NAPA) and an O-ring.
And what about hose clamps? Will I be needing these? Or are the ones in there reusable?

I did a brief search and there are some discussions about this. Anyone have any tips?

Thanks.
 

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It is sounding like a line burst or came undone in the tank. You're on the right track with your list of parts. I replaced the clamps on the fuel hoses, as they didn't seem to grip the desmotimes lines (too skinny for the clamps)

The procedure isn't too hard. Drain the tank (drain hole on bottom right side) Then remove the fuel pump/filter assembly. Replace all your hoses and the fuel filter. My only piece of advice is to make sure to lube the o-ring with petroleum jelly when you put the assembly back in. You'll be there quite a while or break the o-ring if you don't.
 

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Strange you are getting a backfire as my experience has been when a hose lets go... it lets go and the bike won't even attempt to start. AnyWho, assuming you have a spark, and based on the age of your bike you seem to be looking in the right area. As far as the fuel pump removal goes:

1) Perform all work in open air.
2) Remove and drain the tank as already stated in the prior post.
3) Place the tank upside down on a sheet of plywood (or similar flat working area) covered by a soft towel or sheet and remove the (3) 13mm nuts which secure the fuel pump assy to the underside of the tank.
4) Working from the rear of the tank, thread (3) M6 bolts into the base of the fuel pump to begin to back the pump out of the tank.
5) Once you can get some finger tips under the fuel pump, gently pry the pump out. You can use the inside of your legs to hold the tank in place as you are working the pump out.
6) When the pump has been worked out you will need to tilt the fuel pump housing towards its sides to disconnect both vent lines from the base of the pump assy (looking at the bottom side of the fuel pump housing with the word "front" facing the front of the tank, one vent hose will be on the right side and the other will be on the left side next to the short hose that connects to the fuel filter). Remember which vent line connects where for reassembly. Also, remove the white electrical connector which goes to the fuel level sensor. With these items disconnected, you can then work the pump assy out of the tank.
7) Replace all hoses in the tank (2 vent lines, hose from fuel pump to fuel filter and fuel filter to base of the fuel pump assy). It is not likely that you will need to worry about the small diameter hoses that go to the white plastic vent housing. NOTE: when reinstalling the clamps, make sure the screws don't extend beyond the O-ring as they can interfere with proper installation. Also, replace the fuel filter. If using a NAPA unit, it will fit a little awkwardly in the plastic white ring/clamp that secures the fuel filter but not to worry, it will work just fine. Just make sure it is secure and the fuel flow arrow on the filter is pointing in the direction of the base of the fuel pump assy or in the direction of the shortest hose you replaced.
8) Remove and replace the O-ring and, as discussed above, lube it with a small amount of vasoline or dialectric grease. I also lightly lube the diameter of the tank opening where the fuel pump assy is reinserted.

With steps 1 - 8 above complete, you are ready to reinstall the fuel pump assy.

1) Reconnect the white connector back to the fuel level sensor.
2) Reconnect the 2 vent hoses to the underside of the fuel pump assy (again, make sure your connections are correct based on the "front" stamp on the fuel pump assy facing the front of the tank). Also, see NOTE regarding clamp orientation above.
3) Work the assy back into the tank but do not press it in just yet. Make sure the "front" marking on the pump assy is facing towards the very front of the tank and the assy is properly oriented. Now, while kneeling down using the inner portion of your legs to keep the tank in place laterally, press down on the fuel pump assy favoring pressing towards the front of the tank ever-so-slightly but relative evenly, the assy should then press cleanly into the tank.
4) Reinstall the (3) 13mm nuts.
5) Flip the tank over onto your working surface (remove your towel/sheet before doing so).
6) Open the key hole and pour enough fuel into the tank so that you can see (though the fuel cap hole) that it is covering the fuel pump assy towards the rear of the tank. Swish the fuel around a bit and see if there is any fuel leaking out of the bottom. If not, you are good to reinstall the tank onto the bike. If there is, you pinched the O-ring upon reassembly and need to go back to step # 3 of the reassembly process.

Tools needed:

1) 13 mm socket to remove nuts securing the fuel pump assy
2) 3 M6 screws and accompanying wrench to back-out fuel pump assy
3) 7mm socket to remove/replace clamps or a flat head screw driver
4) 3 mm allen head wrench to use on plastic fuel filter clamp
5) Scissors to cut hose to length

Parts:
1) Submersible fuel injection hose which you can get through NAPA or the hose which LT sells which isn't submersible but, personally, I believe LT has a good argument with respect to the hose he sells.
2) OEM or NAPA fuel filter (part # 3032)
3) Viton O-ring through dealer, LT or an O-ring shop (get at least 2 as they aren't too expensive)
4) Clamps (you don't really need to replace these unless they are heavily contaminated or are otherwise damaged)

If my aging memory serves me correctly... that should about do it. Good luck!
 

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Discussion Starter #4
Thanks fella's!
I think the every so oftern backfire is due to j u s t enough fue getting in there to casue it. but not enough to really fire. Prob a line which is severly split.
I ordered things from LT, but ordered a section of fully submersible hose at NAPA. Both should be in tomorrow. I'll be doing the disassembly tonight. Sounds like the biggest pain is draining the tank.
I am going to use a towel-laden cooler to secure the tank while it's upside down. Looks to be just the right size.

Thanks again for the tips!
 

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MCD, that is one great write up. Wish I would have had it before doing mine.

Thank You
Thanks. Slow day @ work.

Mike,

Be sure to put an adult beverage or two in that cooler. Then you can reward yourself once you are done with the tank... or along the way. Your call.
 

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Discussion Starter #7
Well...
The adult bev is in the beer fridge mere feet away from all of the activity. I believe I'm now ready for one.
Bad news (I think). Got everything apart and it looks like the last time I had the filter changed (when they did the belts and checked the valves), my local expert replaced the hoses as well. They look brand new. This was accomplished at 12K miles. (Currently in the mid 17's.) I took them off and inspected everything and see no ruptures or any issues with the hoses.
When I get the new filter, o-ring and hose, I'll put it back together. But I'm not convinced that it is the issue. But I certainly saw fuel squirting inside the tank with each pulse of the motor when attempting to start. Squirt, squirt, squirt, etc...
So now I 'm not sure where to go next. What's the other plastic piece with lesser-looking black line connected to it?
Although I heard the fuel pump sing (normally) when I hit the key, could it be the culprit of the spitting fuel?
Or is what I saw inside the tank normal?

Thanks again for any advice.
 

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Wonder if you have a slight puncture/crack in a hose that isn't obvious unless it is under pressure? Heck, you might need to dive back into the tank if this doesn't work but, unless somebody has a more accurate diagnosis, why not perform the service you were going to do anyway and see if that solves the problem? If you do decide to go this route make sure you don't put too much fuel in the tank when you go to start it. Just in case you need to empty it again to go back in.
 

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If you DO decide to change all the hoses, use ones rated for fuel injection, but make sure they aren't lined with that slick blue silicone material. It has insufficient friction to stay on the connections for the duration of the filter's time in-tank. They will slip off in short order and cause the exact malfunction you described earlier. I speak from experience.

LD
 

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Discussion Starter #10
Thanks. I ordered SAE J30R10 5/16". It only comes in 1' lengths. For about $25. Nuts.
 

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I just replaced all the hoses, O Ring and fuel filter on my 1999 ST2. My bike acted like ti just ran out of gas. The fuel delivery hose had a crack in it and I lost pressure. I bought all the parts from my Ducati dealer. Fuel filter was $35, O ring was $12 and all the hoses were $75. A lot of places will charge $30 per foot for the proper type of hose and only sell in 1 foot lengths. Ordering them from Ducati was cheaper and they were all cut to length for me.
 

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Discussion Starter #12
New thread Starting Soon...

Well, job is complete but I mis-diagnosed the problem. Good news: I changed out the filter, o-ring and hoses. that's looking good. Bad news: No start. There's no spark.

Thanks for all the advice above. Again, look for new thread.
 

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It's too late now but I just saw this thread. That plastic thing is an "air separator" and squirts some gas under normal operation. I went through the whole routine you just did and eventually found that the wire connection behind the radiator was fried so I cut it out and soldered #10 wire in it's place. After that my bike would start just fine.

Good luck on your problem.
 

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Discussion Starter #14
Yeah. It sure does. Wish I'd have known that before I went through the whole process. But It's good for a while now anyway.
Thanks for chiming in. I just climbed (is that a word) around the bike checking relay's fuses connections, wiring, etc. Nothing is jumping out, yet I have no spark at either plug.
Fairing is off. Guess I'll call the shop tomorrow (ug).
 
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