Non return injection

[Bitza]

Can anyone tell me, of any Ducati models/year that have non-return fuel injection layouts. In particular are there any 1000ds models?
I redesigned mine to non-return some time ago using a fuel pump assembly off a R1, fitted with a regulator valve apparently set at 3bar. Had ongoing issues with rich running, with only ecu trim to help. Anyway I came across an advert for a suitable 3bar regulator for Ducati fitment. 749/999/848/1098/1198 Street fighter, 696/796/1000/evo, sports classic 1000, hypomotard 1000/evo. I have looked at parts lists but these all seem to have return fuel layouts. I have fitted the new regulator with positive results, my guess is that the previous one was actually set at 3.2bar.

 

[Bitza]

I've just had a thought, maybe they are all return systems but with the regulator valve in the petrol tank, at the end of return pipe? Any way these particular pumps/regulators are fitted in tanks with an oval pump plate (x6 screws).

 

[Mr Gazza]

I'm assuming you are still using your original carbie tank with no provision for a return?
I would be thinking of drilling the tank where you can see the bottom of the tank through the filler cap. Then put in a compression fitting to make a spigot for a tube to take the other end of a fuel rail. (Must be something suitable or adaptable in 10mm copper?)
Clap some magnets round the hole to catch the swarf.
Added bonus would be being able to see the return squirting.

 

[Dukedesmo]

As far as I'm aware they are all return systems? though I'm not familiar with many bike EFI setups.

916, for example uses a flow/return setup with the regulator in the tank at the end of the return line, that way the fuel supply to the injectors is constantly at the correct pressure so that the amount injected is dependent solely on the time that the injector is open and the excess fuel returns to the tank.

I'm currently rebuilding an old Land Rover with a Rover V8 engine and that works in the same way, albeit the regulator is at the end of the fuel rail rather than in the tank but any excess fuel is then returned to the tank via the swirl pot/high-pressure fuel pump which is also not mounted in the tank.

Fitting it all in the tank makes for a nice compact system, ideal for bikes.

As for Monsters, although mine has carburettors, it has a fuel-injection tank (M900i) with flow/return and an internal, electric pump that I have configured much the same as you would for injection but without a regulator.

In essence the pump cycles fuel from the tank, back to the tank with a 'Y' connector to the carbs, allowing them to take as much as they need with the excess returning to the tank, not much fuel pressure is required and carbs are self-regulating anyway hence no need for a regulator.

 

[Bitza]

Good to see that we all have some down time on Sunday mornings. Obviously I've been rambling on a bit, but I was just wondering if there was something I could learn from the Ducati set ups.
I have two alternative fuel pump set ups that I can fit into my adapted carbie tank. The first is a return set up with an external regulator as fitted to first gen ie bikes. This gave good low down running but poor/weak running top end. The second set up is non-return and has the regulator (see pic) set into the pump housing. This gave good top end but poor/rich low down running, and of course it weighs less too. Obviously I opted for top end & lightness to develop further. The plan is to see how good I can get it, before getting the ecu remapped.

 

[jerry]

Dont all the carbed models also have a return spigot in the tank back from the carbs ,, My 750ss and M750 certainly do ...