Fuel pressure regulator goes on supply or return?
TECH Enthusiast
Joined: Mar 2010
Posts: 519
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If external pump or pumps your gonma want to put a 100 micron filter before the pump to keep any possible garbage from getting in the pump and damaging it or clogging it. 100 micron filter is basically a screen to catch big stuff.
After the pump your going to want a 10 micron so that you can catch everything possible that you can cause after that it will end up clogging the injectors.
If your using intank pumps then I would assume somewhere along the feed line to the motor before the rails your gonna want to put a 10 micron or somewhere around that rating filter in there.
Pre filter on intank setups is usually in the form of a sock on the bottom of the pump to keep and possible junk from being sucked up.
Mine has a -10 feed with a Y going into -8 fittings in each rail, then two seperate return lines coming out of the rail and into the regulator. I have heard is is important to try to make sure both of the lines coming out of the rail are equal length. Not sure how true this is, but I did it anyways, haha. From the regulator I have a single -10 going back to the tank.
I used the larger line due to using E85. I have had bad experiences using too small of a return on E85 and it becoming a restriction when using very large pumps. Actually had a car that at idle would not go lower than 55 psi fuel pressure, but then as the motor started actually using fuel it would drop down to 45psi before climbing back up with boost. Until I figured out what was happening I was having a HELL of a time tuning the car, lol.
I used the larger line due to using E85. I have had bad experiences using too small of a return on E85 and it becoming a restriction when using very large pumps. Actually had a car that at idle would not go lower than 55 psi fuel pressure, but then as the motor started actually using fuel it would drop down to 45psi before climbing back up with boost. Until I figured out what was happening I was having a HELL of a time tuning the car, lol.
Depends what pump your using.
If external pump or pumps your gonma want to put a 100 micron filter before the pump to keep any possible garbage from getting in the pump and damaging it or clogging it. 100 micron filter is basically a screen to catch big stuff.
After the pump your going to want a 10 micron so that you can catch everything possible that you can cause after that it will end up clogging the injectors.
If your using intank pumps then I would assume somewhere along the feed line to the motor before the rails your gonna want to put a 10 micron or somewhere around that rating filter in there.
Pre filter on intank setups is usually in the form of a sock on the bottom of the pump to keep and possible junk from being sucked up.
If external pump or pumps your gonma want to put a 100 micron filter before the pump to keep any possible garbage from getting in the pump and damaging it or clogging it. 100 micron filter is basically a screen to catch big stuff.
After the pump your going to want a 10 micron so that you can catch everything possible that you can cause after that it will end up clogging the injectors.
If your using intank pumps then I would assume somewhere along the feed line to the motor before the rails your gonna want to put a 10 micron or somewhere around that rating filter in there.
Pre filter on intank setups is usually in the form of a sock on the bottom of the pump to keep and possible junk from being sucked up.
9 Second Club
Joined: Nov 2003
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From: Norn Iron
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Verdad Gallardo TECH Enthusiast
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I too use a 10 micron post pump, my injectors got gummed up and a few stopped flowing anything all together from the corn....sent them to fuel injector connection and he fixes them up. He said the only way to keeo it from getting that bad is to send them in twice a year to get cleaned.
I used the one on my wrx for 3 years on e85. It got clogged quickly at first from varnish, but after that change it was good. I believe the Ss is the 100 micron and the 10 is cellulose maybe? I would rather have "white hairs" trapped in my filter than my $1000 injectors!
I'm using a spin on diesel paper filter before the pump. It looks just like a spin on oil filter.
I have small screens in the injector hats from ID.
Thinking I ought to have a peek at those filters and see if I'm getting any degradation of my paper filter.
This is my first experience with E85.
Good info, thanks.
Ron
I have small screens in the injector hats from ID.
Thinking I ought to have a peek at those filters and see if I'm getting any degradation of my paper filter.
This is my first experience with E85.
Good info, thanks.
Ron
TECH Enthusiast
Joined: Mar 2010
Posts: 519
Likes: 2
I have a 10 micron in stainless. Like I said if the paper filter says it's not compatible I wouldn't try your luck with your motor.
If you are looking at the regulator The line on the left is -10 feed the line on the right is -10 feed as well, it hits the Y block and splits to (2) -8 lines. Those lines are fed to each rail constantly maintaining your desired FP. The line on the bottom of the regulator is -8 return and goes strait to the fuel tank.
And I'm no engineer, but I just can't see the way oscs had/has is (the way I'm switching to) being a problem. This is why, I believe the pressure everywhere in the entire system will be the same. Ex: the pressure right after the pump and at the very end of the dead headed rails. Just like pressure inside of an air compressor is equal everywhere. And saying you're going to run out of fuel with it one way vs another also makes no sense. The orientation of the lines does not make a pump flow more volume. Just my observation.
9 Second Club
Joined: Nov 2003
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From: Norn Iron
And I'm no engineer, but I just can't see the way oscs had/has is (the way I'm switching to) being a problem. This is why, I believe the pressure everywhere in the entire system will be the same. Ex: the pressure right after the pump and at the very end of the dead headed rails. Just like pressure inside of an air compressor is equal everywhere. And saying you're going to run out of fuel with it one way vs another also makes no sense. The orientation of the lines does not make a pump flow more volume. Just my observation.
He has effectively re-created a late model OEM setup. ie dead end rails with a regulator closer to the supply source.
The only real difference is the length of pipework involved between regulator and rails etc.
Now in theory if fuel consumed by the injectors exceeded the flow ability of the tee piece and lines that feed the rails, pressure in the rails could start dropping, but pressure on the feed side of this tee might still appear fine.
It isnt very likely to happen if pipe sizes are adequate, but it is still a less desirable way to configure it that placing the regulator after the rails.
Really given the amount of pipes already in the engine bay, I can see no positives to configuring it the way he has.
It would be just as easy and maybe less pipework to place the regulator in the most favourable location..ie after the injectors.
Why?