My question might sound complex to those who have not had a fuel sender apart but bare with me. For anyone running decent power on an R26/225 you will already understand the fuelling concerns. The aim is to create a return setup without installing a separate swirl pot and external pump. I am trying to modify the stander sender unit into a return setup, the top part where the fuel lines connects is sorted, I am using the upper part off a diesel unit. However, the part of concern is the pump housing, is it possible to modify or create a blank for the fuel pressure regulator in order to send full pump pressure to the rail and subsequently the new fpr and return line at the engine bay? Does anyone have details of the Regulator blank or modification? Is it as simple as removing the nipple (only way I can describe it) from the lower part of the regulator and refitting or do I need a blank making up without this part? Pictures to follow in due course Kirk
Hi Korky I have modified my fuel pump to take a DW65 fuel pump, i then needed to send a higher pressure to the fuel rail as there wasn't enough fuel on full boost, i fitted a 5 bar fuel regulator in the tank but it wasn't a straight swap, Renault in there infinite wisdom used a smaller diameter spindle, the standard one is 10mm an the Renault one is 7.8mm if i recall correctly, so i had to turn the replacement one down, to be honest if you were to block the inlet/outlet or both on the original regulator vale you would get full pump pressure up the fuel line.
As Ian said, easiest way it to just put a higher pressure regulator back at the sender. That way it would still be the regulator at the rail doing the regulating.
In hindsight I should have swapped to the diesel sender top, probably cheaper than the airoquip fittings to make the return
Cheers mate, this mighty sound daft but is the FPR 5 bar static? I imagine the vacuum is only needed for rising rate at 1:1 which there shouldn’t be with it being situated in the tank?
No the one in the tank feeds 5 bar to the fuel rail and then i have a 3.5 bar rising rate at the injectors, i am running a 250 ruel rail as well.
Yes the 5bar regulator from in tank will be 5bar static, wouldnt adjust by a great amount for rising so wouldnt be a problem if it was above or below that as static would definitely still be higher than the rail regulator. Just be careful what regulator you use at the rail as it will need to be able to drop the potential 5bar from the tank down to the 3.5. Depending on what pump you use the stock 3.5bar reg probably wont keep up on low fuel load. Would be best to test the rail pressure once its set up to be sure.
I’m running a Dw65c pump 265l/hr flow rate and trying to create a return system using the standard sensor unit. I propose to run a Bosch 3.5 bar regulator at the rail, however if the consensus is this could be insufficient I will run an adjustable regulator (AEM or Fuel lab or similar) with built in pressure gauge to monitor the fuel pressure
I had a blank made in the machine shop at work to see if it will work before I commit to buying the addition fpr. Looking at the sender unit I am now thinking that this blank may possibly restrict the flow if you get me? What do you think? @Big Uno @ianplymouth
Looks good, I didnt take my sender apart so not sure on the arrangement, as long ad the fuel can flow past without resistance it will be fine.
It wont restrict the flow, it is in the unit and just dumps the excess back into the tank, looks good
Can I connect the return line to the sender and just allow fuel to flow back into the tank or do I need to add a line beck into the sender or tank with a non return valve or similar?
No real need for a valve, as long as the return is at the top of the tank sonewhere there will be next to no resistance against the fuel in the return line and nothing should be trying to go down it the wrong way
For anyone searching in the future, this setup does work with the 225 or 1.6 petrol sender unit and the diesel top. A Dw65c fuel pump and a fpr blank. Note that when the blank is machined you will need a small channel in it to allow fuel to pass but still blank the return. This will allow you to run a fpr at the front and have a true return system I think this is the only return system solution without the need for a swirl pot.
I need to look at changing to a sender top with the return really. Being able to run a hose from the return outlet to the bottom of the tank helps stop air bubblds in the fuel.
At the moment my return is just open into the top of the tank, is running a line to the bottom of the tank necessary? Would this not prevent the return line from draining as it isn’t under pressure?
Its not needed, just helps stop air bubbles as the fuel drops. No it wouldnt stop the return from working, the line pressure that is behind the regulator would push it down th line even if there was a restriction, secondly as the regulor will usually be placed higher than the tank level it will natutally return down to the tank fuel level
Valid point mate, I have some braided line left so might go make the small bit up, pull the sender and drop it back in the tank. I have became accustom to the smell of petrol, the amount this tank has been opened [emoji23]
Can just fit it so it will return to under the fuel level. Doesnt need to be braided any ptfe or fuel safe line will be fine The return should be contstantly working, just another thing to consider is fuel temperature, you may find it heats the fuel as I have a similar problem on low level fuel. Doubt it will be an issue with your pump though, if you are using stainless braided line just keep in mind where you run the lines as they may warm up the fuel, and insulator can be used to help stop it
Just used normal fuel line for the in tank return as you suggested as it was much easier, used around 200mm. I have ran my fuel lines where the existing ones go, if I find they heat up I will get an insulation cover as you suggested, cheers mate!
Yeah that will be fine mate, thats the reason I want the diesel sender top on mine. Its more important in your case to make sure there is not air in the fuel as if you wont have a swirl pot the fuel will be going directly to the rail. So I think its just better with the hose on it And fuel temp probably wont be a issue for you, just keep your eyes on it, if the engine is hot and at idle for a while you will find it will probably warm up. The mk3 rail seems to do a fairly good job soaking up heat as its stainless. Worst case for me I will just look at fuel cooler lines under the car
Hi mate, this might be a long shot as this is an old post but when you say a small channel for the fuel to pass and block the return, what do you mean? I’m looking at doing this to mine, any pics would be great. TIA
