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Discussion Starter #1
Can anyone tell me if the fuel pump on my 98 ST2 is supposed to run continuously once it is started? And if it is why is it that when i look into my fuel tank i can see fuel being pumped back into the tank. And lastly if all of the above is correct what are some other potential problems that can lead to fuel problems? I believe that it is not getting enough fuel because it was running rough recently and acted as if it was starved for fuel and when i turned the fast idle up it seemed to help. Any ideas???
 

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Your fuel filter may be blocked. When was it last changed ?
 

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And if it is why is it that when i look into my fuel tank i can see fuel being pumped back into the tank.
There is a return line from the throttlebodies that circulates fuel back into the tank. If there is an excessive amount, one of the rubber fuel lines inside the tank can be split.
 

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Ditto what Terry said. If the fuel hoses inside the tank are original, they are ready to be replaced. Chances are the fuel filter in there is full of rubber bits previously related to aforementioned (now dissolved) hoses. Fix it before it croaks altogether.

pg
DD
 

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Even when it has great hoses/connections, there is a minor amount of gurgling in the tank. Return line is one, and there's an "air separator" that also discharges into the tank. Have a friend with a newer DUC? Go listen and watch their's
 

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Discussion Starter #6
Thank you all i am going to try to attack this problem soon and see what i can find...ideas on where to get lines from or can i just get some fuel line and go from there?
 

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Thank you all i am going to try to attack this problem soon and see what i can find...ideas on where to get lines from or can i just get some fuel line and go from there?
I forgot the actual number or type, you can get the lines at NAPA, but make sure it is hose for fuel-injection systems. There is a difference between "just" fuel hose and high-pressure hose for fuel injection. Last I heard, I think the fuel injection hose was something like $8-$10 per foot. Maybe someone here can provide better details.
 

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Don't remove your fuel pump assembly without at least 2 spare O rings on hand.
I've never had an issue with destroying an o-ring when reinstalling the fuel pump, but others have. For o-rings, I've used the -247 referenced o-rings from McMaster-Carr, twice in my '02 748 and twice in my '98 ST2, without a problem. They are typically a lot cheaper than other sources.

AS568A Dash Number 247
Type O-Ring
Material Vitron
O-Ring Type Standard
Cross Section Shape Round
System of Measurement Inch
Width 1/8" (3 mm)
Inside Diameter 4-5/8" (118 mm)
Outside Diameter 4-7/8" (124 mm)

I don't remember if I ordered the mil-spec ones (#1201T879) at $13.52 for 5 or if I bought the standard ones (#9464K548) at $8.76 for 5.

Note - Another forum member once gave the metric dimensions as 120 mm ID and 3.5mm thickness for the o-ring.
 

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Thank you all i am going to try to attack this problem soon and see what i can find...ideas on where to get lines from or can i just get some fuel line and go from there?
If you're replacing the fuel hoses inside the tank then normal fuel injection hose may not last very long. You need hose designed to be immersed in fuel. There appears to be only one type available in the US. Go to O'Reillys or Napa and ask for injection hose with the SAE 30R10 rating. It should be printed on the hose. It only comes in 1 foot lengths that range in price from $23 to $30. Normal fuel injection hose is SAE 30R9. To replace all the large diameter hoses in the tank requires 3 one-foot pieces. Two are for the vent and overflow hoses that run from inside the top of the tank to the pump assembly. The third piece gets cut into a couple of shorter pieces and replaces those on the fuel filter.

Also, there are two molded hoses on the pump assembly running from the air separator. I don't know of a source other than Ducati. For the ST3 they are part numbers 590.1.059.1A and 590.1.058.1A. May be the same part numbers for the ST2.

I also have found that the hose clamps on the Ducs don't work well with the smaller 5/16ths hose we get here in the US. The factory clamps are just a bit too large and don't tighten down well. You'll need 5/16 inch clamps. There are some good ones made by a company called Ideal just for fuel injection applications. These are smooth clamps so they won't damage the fuel line. I think the Ideal part number is IDE52F15. I've found them at O'Reilly's parts store locally or you might find them at some other parts store. They were selling for $1.00 apiece at O'Reilly's. You can also find them at places like Autobarn on the net. Autobarn had a minimum order of 10 at $0.69 each but shipping might bump the cost up above local cost. The net is a good option if you can't find them anywhere else. If you're replacing all the 8mm hose pieces in the tank with the 5/16ths then you'll need at least 8 so you might as well get a box of 10.

I also recommend that you have a spare O ring on hand. Sometimes they stretch a bit and don't fit too well or become damaged a bit during reassembly. Just before you're ready to pop the complete pump assembly back into the tank smear a small amount of Vaseline on the lip of the tank and on the O ring. If the O ring isn't seated correctly you'll find out very soon after putting some fuel back in the tank. Check this before putting the tank back on the bike.

Bill W.
 

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I've always used the normal 5/16" (never use 3/8") SAE 30R9 hose inside the tank. I replace my fuel filter every 2 years and carefully check and sometimes replace the hoses. I also use the Ideal hose clamps.

Jeff in Colorado
 

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Discussion Starter #15
Ok i finally got my pump pulled out today... Do i need to replace all the lines while im in there? There were 2 that i had to disconnect from the pump to get it out. They look like they go to the filler cap. Also any suggestions on a good cleaner to use to clean the tank out?
 

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"Do i need to replace all the lines while im in there?"

Are any of the lines cracked and crumbling? Are rubber chunks floating around in the bottom of the tank? Then replace and the lines, filter, and clamps. And do your best to clear anything out of the fuel pump. I would just use clean gas to clear the tank if needed.

There is no pressure on the 2 lines that go to the fuel filler. One is for overflow if you overfill and the other allows air to enter the tank to replace fuel that leaves the tank.

I would say that since you went to the trouble to get into the tank. replace the filter, hoses, and clamps regardless of their condition.

Jeff in Colorado
 

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Discussion Starter #17
There are 2 lines that are connected to the air separator. they do not look to be fuel injection line but they feel pretty weak so i was going to replace them. Any suggestions on the type of line to be used?
 

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Those are the two molded hoses I referred to in my earlier post back on Oct 13.

I don't know of a source other than Ducati. For the ST3 they are part numbers 590.1.059.1A and 590.1.058.1A. May be the same part numbers for the ST2.
Not sure if there is any other type of hose out there that will fit and will also stand up to fuel for very long.

Bill W.
 
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