Ducati.ms - The Ultimate Ducati Forum banner

1 - 16 of 16 Posts

·
Registered
Joined
·
14 Posts
Discussion Starter #1
Started up my '95 SS/SP this morning and noticed that it took more coaxing than usual to get it to idle.

Rode around the neighborhood for a few minutes and found that while the engine ran, it would bog a bit when I'd whack open the throttle or shift into second.

After about 5 minutes, my low fuel light came on, so I went and got some gas and the problems disappeared.

I ended putting about 3.5 gallons in the tank.

My question is, is this normal? Seems like I still had a fair amount of fuel in the tank to be experiencing bogging issues. Is the low fuel sensor something that goes bad or needs calibration? It was a cool morning so I'd assume the light would come on even earlier than normal.

One thing is that my bike has FCRs installed by the PO. I was checking out the fuel lines and I noticed that the return line from the carbs just goes straight back to the tank -- no restrictor or anything. Is this normal? Just wondering if there's something that's supposed to be inline there. (Incidentally, it makes my petcock pretty useless, as fuel just pours out thru the return line!)
 

·
Registered
Joined
·
6,132 Posts
I DO NOT have FCR’s, and know little about them, but I don’t think the fuel delivery should be set up any differently than Mikunis. Your delivery line from the fuel line should run to a “Y”. The return line connects to the “Y” and the other end goes to the return at the tank. The remaining connection goes to the carbs.
The Important Part : Inside the return line is a jet or “pill” , a restrictor that only allows a certain amount of fuel to flow back to the tank, forcing the rest to go to the carbs. Without the pill, too much fuel will return to the tank and starve the carbs. The fuel pump is really there to insure adequate flow when the tank level goes below the fuel level in the carbs, so when you reach that point ( apparently 3 1/2 gallons) the carbs can starve for fuel even with the pump running .
 

·
Registered
Joined
·
14 Posts
Discussion Starter #3
Ah yeah, that makes sense. I don't have a "pill" on mine. I think fuel delivery should be the same. If anything, might be more important for the FCRs as I think they are a bit thirstier than the stock ones.

Is the pill kind of a generic part or should I be trying to find a Ducati part number for it?
 

·
Registered
Joined
·
6,132 Posts
As far as I know it’s a Ducati part and used on so many bikes it must be available through them. I don’t know if it’s the same size for every bike, best to get one for yours if there is an option. Many people don’t realize it’s there and toss it when replacing hoses.
 

·
Registered
Joined
·
179 Posts
The pill is hard to find as it is just stuck inside the stock fuel hoses. Lot of them probably accidentally get thrown out when the owner changed the hoses. That said I'm not sure it is 100% required. I would start by double checking that the hoses don't get kinked when you lower the tank.


If the problem only exists when the fuel level in the tank is low, check that the fuel pump is delivering. If it goes away after briefly opening the tank, verify that the breather tube isn't blocked.
 

·
Registered
Joined
·
637 Posts
also check inside the tank and make sure none of the internal fuel lines have cracks in them--If there is a crack that is above the level of the fuel at that point it could be sucking air and not giving a good solid fuel delivery
 

·
Registered
Joined
·
637 Posts
Always look for the easy stuff first, It can & will save you time normally, --Then if needed dive in deeper
 

·
Registered
Joined
·
1,822 Posts
also check inside the tank and make sure none of the internal fuel lines have cracks in them--If there is a crack that is above the level of the fuel at that point it could be sucking air and not giving a good solid fuel delivery
This is very likely, imo, I don't have the "pill" in either of my bikes hose return lines but I rarely run the gas down low enough to starve it. When I did however, shutting the bike off for 2 minutes allowed the gravity feed to load up the lines again which gave me enough to get to a gas station.

Perhaps accidentally I fixed the "pill" issue last year because I also have a metal inline shutoff valve after the "T" (upgraded to brass from OEM plastic Y) and a fairly large external (clear) inline filter which adds a significant reserve of fuel to draw upon regardless of how much is spitting back into the tank. This made the choke point at the filter instead of the Y or the "pill" for returning fuel to the tank as an emptying filter has less resistance along with a vacuum effect pulling fuel into it rather than the return line. I have never seen the problem since I did this.

I can see the value in the "pill", so I might order two if they are cheap enough.
 

·
Registered
Joined
·
6,132 Posts
As stated, the value in having the restrictor pill in the line is really when the tank level gets low. Obviously Ducati thought that was a good idea. I agree. It also may cause more fuel to be available at the carbs because line pressure would be raised, possibly preventing fuel starvation and engine failure. Obviously Ducati thought that was a good idea. I agree.
 

·
Registered
Joined
·
6,132 Posts
By the way, I also have an external filter and shut off valve, plus the pill. I like being repetitively redundant over and over multiple times.
 

·
Registered
Joined
·
637 Posts
I too have dual fuel filters and an external fuel petcock
 

·
Registered
Joined
·
1,822 Posts
Dual fuel filters are really necessary in the remote areas I often ride in, along the border - in the Res areas, small tumbleweed towns,.... gas quality in 100 degrees+ F for 100 days a year 24/7, even buried in tanks underground is always suspect as there are no Federal inspectors checking for quality out there in the wild wild West and the Arizona State inspectors have no jurisdiction.
 

·
Registered
Joined
·
14 Posts
Discussion Starter #15 (Edited)
Really appreciate all the advice.

Finally had some time to tear into the tank today, and found that the fuel hoses were connected incorrectly. The overflow drain hose was just kind of dangling around the tank. It was attached at the bottom, but not the top.

When I turned the key, I was soaked down with fuel spraying from that hose, because it was attached to the return line from the carbs. Also explains why the tank leaked so badly from the cap when it was propped up.

Connected everything the right way, hopefully that and the pill will help get things working better.
 

·
Registered
Joined
·
804 Posts
It is pretty common for the hose to disconnect from the drain hole in the fuel cap carrier. Make sure it is the correct size hose and clamp it tightly.
 
1 - 16 of 16 Posts
Top