Few fuel system queries before I'm at home at the weekend to attack the problem!

First of all, I haven't got the duratec fuel rail to had at the moment so was I was hoping that somebody could tell me how the regulator works as I'm hoping to use the standard rail. I gather that its a fuel pressure adjuster from the inlet manifold but can you leave it on the rail with no affect? I.e. will there be an affect if the rail is used and it is left on there not connected?

Following on from the above. It has been mentioned before but my hope is to do all of the fuel 'management' at the back of the car (so hi+lo pressure pumps, filters, swirl pot and tank returns from regulator/swirl pot ect) and have a single regulated pressure line to the front of the car with no return from the rail. I was wondering whether anyone has tried this with success or not? Will the pressure loss along the tube be appreciable, will it matter if the pressure is regulated with respect to rail pressure? This is the method we used with an in tank pump/reg on the formula student car and it seemd to work great, just have slight concerns due to the length of the run to the rail!

Apologies to cover a subject that has been done to death one way or another!

Cheers

Andy

There will be a few problems with not running a return from the rail - the fuel flow through and back to the tank does a lot to keep the system cool , so you could end up with very hot fuel in a very hot fuel rail
Also - if you run out of fuel , the injectors will run dry untill they have let all the air through , which wont happen with a return as it will `self bleed' as soon as the pump runs .
And.............sudden acceleration will cause a pressure drop , which is one reason the regulator is mounted on the rail on most cars .

Apart from all the above , I cant see a good reason for not doing what all production car manufacturers (and AFAIK) all after-market suppliers do

Andy,

The method you describe is the same as used by folk who reuse the in tank bike pumps (at least those from Suzuki) it does seem to work.


Fuel flow will still keep the hose and rail cool (you are not recycling hot fuel which is a definite source of trouble), I haven't found a problem with this, although my underbonnet temperatures are not that high.

I guess you would have some acceleration effect on the fuel, but even at 1g acceleration the psi drop (assuming 2 meters from front of car to regulator) would only be 2.4psi (so a 3% change in fuel flow) . Actually this is a bit more than I realised.

The other problem is that if you run a pressure regulator that is manifold pressure referenced (can't remember the words), then you still need to run a length of hose back to the regulator.


So, you can do it the way that you describe, it will work, but regulator at front is probably better (I think I will change the plans for my car now that I have thought about it properly).

Matt

interestingly some BMW build the regulator into the filter and have one fuel line to the engine.

Combining parts might save a quid or two.





I don't know whether they use the filter as a sort of bubble trap too.

more than one way to skin a cat (not that I am encouraging such behaviour)

No reason why it can't be done, most major manufactures are moving or have moved to this system now (toyota have been doing it since 1998 on various cars to reduce evapourative emissions)

I think its a great system, as you are not recycling hot fuel back to the tank, also on the engine I have it produces 210hp from 2L as standard so can't affect performance too much!

The fuel reg in the toyotas are built into the pump and filter assembly in the tank, so runs at a constant pressure - therefore the ecu needs to be mapped to match this. And also have a pulsation damper on the fuel rail to smooth out the pressure.

I say go for it, you should be able to get pump filter and reg assy pretty cheap from a production car that uses the same system (mine mounts in the top of my swirl pot, so keeps everything tidy)