derekbruceyoung
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| posted on 28/5/24 at 05:48 PM |
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Fuel pressure regulator for return-less system or convert to return?
I am looking to move away from using my stock 2009 ZX10R tank and pump in my build and switch to a fuel cell.
Does anyone have a recommendation for a return-less fuel pressure regulator? I only seem to be able to find low-pressure carb units.
Or is adding a return as simple as adding a T connection at the injector feed port and send a return line back? In my past EFI experience, the return
is on the far side of the fuel rail from the feed, but as long as the pressure is there, the location of the return shouldn't matter, right?
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40inches
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| posted on 29/5/24 at 09:51 AM |
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I used a Malpassi regulator, the return is on the bottom of the reg.
Link
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voucht
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| posted on 29/5/24 at 05:42 PM |
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If you have fuel injection, you have a return line. Perhaps everything is in-tank, but it is there. It all depends on how your fuel circuit is
designed. So there is no "returnless" fuel regulator per se. There are 2 and 3 ports fuel regulators.
2-ports regulator are designed to be installed on the return line, after the ramp, or at the end of the ramp if attached directly to the ramp
3-ports regulator are designed to be installed on the feed line (pressure), and the return is most of the time on the bottom of the reg. as 40inches
says.
If you want to use a 2-port regulator, you need to put it on the return line.
If you have only one line, then it means that return is made in-tank after the reg. See picture 3 below, it should be more or less something like
that. Then either you keep this configuration, either you need to install a 3-port regulator on the feed line and install a return line back to the
fuel tank.
Here are 3D sketches I made a few years back for the catalogue of a motorosports hydraulic systems company I used to work for. They show different
set-ups and where the regulator is placed on the circuit.
 
Description
 
Description
 
Description
 
Description
Fuelab makes both 2 and 3 port regulators. They are very good and very reliable, but for race cars so they are expensive. Exemple :
https://titanmotorsports.com/products/fuel-pressure-regulator-84
Myself, I have installed a 2-port regulator on the return line of my Sierra 2.0i DOHC when I built my Haynes Roadster. It was a cheap chinese model
like this one, but it is still working.
https://www.amazon.com/Universal-Aluminum-Adjustable-Pressu
re-Regulator/dp/B07FSMQ91Y
Hope that will help 
https://vouchtroadster.blogspot.com/
https://cafrazx550.blogspot.com/
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derekbruceyoung
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| posted on 29/5/24 at 05:56 PM |
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Ahh yes, that makes perfect sense. Yes the pump in the tank must have a "return" (or bypass) but since it's all integrated I
didn't think about the fact that it exists there. This is all quite straight forward now.
Thank you both for your replies!
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adithorp
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| posted on 30/5/24 at 06:45 AM |
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quote:
Originally posted by derekbruceyoung
I am looking to move away from using my stock 2009 ZX10R tank and pump in my build and switch to a fuel cell.
What's your reason for changing? If its not broken... etc.
Don't think you can just T it into the feed line. You'd need a return to either a swirl tank or back to the tank.
Voucht's diagrams are excellent. Only thing I'd add is the last one with the pump at the engine isn't a great way to do it; hp pumps
don't like to suck and do should be as close to the tank and as low as possible.
"A witty saying proves nothing" Voltaire
http://jpsc.org.uk/forum/
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derekbruceyoung
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| posted on 30/5/24 at 07:09 AM |
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I'm switching over as I want more capacity and I'm also redesigning/offsetting my chainline 120mm which would crash into the bike tank so
the tank needs to get narrower. I've built an EFI system before into a carb'ed car years ago, and it's all coming back to me slowly
https://photos.app.goo.gl/NkQH91YyXv26FVSz8
One option is to use a low pressure pump to fill a ~2L surge tank from the cell with my stock bike pump mounted on the bottom face of the surge tank
supplying as it does now.
@voucht -- really nice graphics!
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