Fuelab fuel pressure regulator I think I am over running it ?

[onesickcrx]

So I have a Fuelab 515 fuel pressure regulator with -10an feed line -6an return. Once I start my car and my fuel pumps get full voltage I can not turn the fuel pressure down. Meaning I have the screw completely out of the top of the regulator and its will chill at 50-55psi of fuel pressure and I am looking for 35psi, soon as I turn screw in pressure goes right into the 70-80psi range or more. I have tried different gauges same pressure reading. I called up Fuelab because I must be missing something they had no real answer for me and told me to check for collapsed hose and that the internal orifice hole is suppose to be that small /ubbthreads/images/graemlins/banghead.gif

Is it me or shouldn't the hole that feeds the return hose in the regulator be bigger then .132" ID I mean my -6an fitting is .288" ID ...... So thinking about this since my -6an hose is more then double the size of the regulator internal hole my hose can flow more then quadruple the amount the regulator can.... so this brings me back to the damn return orifice is to small in the regulator!

I was getting very frustrated last night I hope someone can shed some light on this for me /ubbthreads/images/graemlins/dunno.gif

 

[onesickcrx]

 

[jepherz]

-6AN is supposed to be 6/16", or .375 internal diameter, at least the hoses are. But yeah, I'd say that hole is a major problem. It's not going to limit your return to 1/4 of what it should be, but it's a HUGE bottle neck.

Did you ask them why they made the return so small when you can put a -6AN fitting on it?

 

[onesickcrx]

Yea I am measuring the smallest section of the -6an fitting just so I am comparing apples to apples.

 

[onesickcrx]

I talked to Fuelab they asked me a ton of questions... a couple hours later THEY CALLED ME BACK WITH ANSWERS! /ubbthreads/images/graemlins/applause.gif

I ordered a regulator that has a bigger diameter return hole I think around 3/8" /ubbthreads/images/graemlins/devil.gif . I will post up the results as soon as it comes in next week

I am guessing my fuel system is working pretty well if I out flowed the regulator /ubbthreads/images/graemlins/dunno.gif

 

[Adorsey]

Weird it would be that small of a hole.. Did you have the vacuum line disconnected when setting the fp?
Not doughting your intelligence, just curious...

 

[brisvr4]

What were the answers that they had for you?
I just looked on their site and they do quite a few different versions of the 515. Could be that you got a carb version or NA version perhaps?

 

[onesickcrx]

Quoting Adorsey:
Weird it would be that small of a hole.. Did you have the vacuum line disconnected when setting the fp?
Not doughting your intelligence, just curious...




Nope it was on /ubbthreads/images/graemlins/wink.gif

 

[onesickcrx]

Quoting brisvr4:
What were the answers that they had for you?
I just looked on their site and they do quite a few different versions of the 515. Could be that you got a carb version or NA version perhaps?



Well, they asked me for my regulators serial number its on the back of the regulator. They looked that up on the computer which has all the specs of that particular regulator. They asked me what size fuel lines I had and made sure I wasn't out flowing them... Then what fuel pumps.... Then what voltage I am running in the car... How many psi am I looking to have at idle....

When they called back they said the new regulator should have no issues with what I am running I may need to upgrade to a -8an return since the -6an hose will be the smallest part of the return now.... I guess I will find out when I install it

 

[Adorsey]

Quoting onesickcrx:
Quoting Adorsey:
Weird it would be that small of a hole.. Did you have the vacuum line disconnected when setting the fp?
Not doughting your intelligence, just curious...




Nope it was on /ubbthreads/images/graemlins/wink.gif






Well, when adjusting fuel pressure. The vacuum line should be disconnected from the afpr, and the line should be plugged, or cripmed to not allow a air leak.
Then the car should be turned off, and install the vacuum line. Then your Fuel pressure should be spot on.
/ubbthreads/images/graemlins/wink.gif

 

[onesickcrx]

I set the fuel pressure at 37psi with car off with a external mini battery to the fuel pumps. Once the car started and the full voltage to the pumps goes back up to 13.8-14.2 I cant turn it down... capped off or not fuel pressure wont come down from 50psi+ /ubbthreads/images/graemlins/dunno.gif

 

[curtis]

For future reference

What pump are you running?

What line goes to the tank?....I know you said -6 but is the -6 running over from the regulator to the factory return or all the way back to the tank?

 

[brisvr4]

+1 on the questions Curtis has asked.
What was the model number on the back of the reg just out of interest?
Also, how much power are you looking to make if you need a -10 return to the reg? What size is the feed that you are using from the tank?

 

[Adorsey]

Quoting onesickcrx:
I set the fuel pressure at 37psi with car off with a external mini battery to the fuel pumps. Once the car started and the full voltage to the pumps goes back up to 13.8-14.2 I cant turn it down... capped off or not fuel pressure wont come down from 50psi+ /ubbthreads/images/graemlins/dunno.gif



Im just letting you know, pre my first post.
I do see that restriction in your afpr. I would have reason to believe that's the problem.

Im curious on this setup too -10 to the rail, what where you doing those last three years? /ubbthreads/images/graemlins/smile.gif

 

[curtis]

Yea just map out the system for us. /ubbthreads/images/graemlins/grin.gif
filter in the tanlk until the fuel splashes back in from the return, to include pump types, filters and the micron ratings of them and if theres a surge tank etc...

 

[onesickcrx]

Ok my current setup is

I have two 255hp in tank pumps that go threw a Full Blowns sending unit... On top of the sending unit I have a -10an fitting then goes to my -10an hose all the way up the car to engine bay where my -10an fuelab filter which is a 40 micron / Stainless Steel filter. -10an feed line from there to the rail which is a Mangus -10an rail... on the other side of the rail -10an hose to the Fuelab regulator -10an inlet to a -6an return fitting and hose the hose goes all the way to the back of the car and directly into the sending units return.

I would have posted this up last night but doing it threw my Iphone wasnt happening lol

 

[onesickcrx]

The current model number of the regulator is 51501

 

[onesickcrx]

I was just going over the specs of my old regulator its suppose to good up to 570LPH. I think at most I should be 538LPH at 14 volts so now thats got me thinking is something else wrong? hmmm... I think I should just wait to see what happens with new regulator /ubbthreads/images/graemlins/crazy.gif

 

[curtis]

Ok here's my thoughts on two pumps. In a perfect world two 255 would pump 510 at 43 psi all day long at 12 volts but they don't you could test every pump made and might not find two pumps that flow the exact pressure and volume all day long, I'm talking right down to 4 decimal places. Temperature of the fuel , temp of the day voltage etc all change there output. Now with that said if you have built a car that needs 500lph and one fails how do you know it failed and if it did.... does the backside of the pumps have a one way check valve to keep one from backfeeding the other. If one dies the other want feed all the fuel to the motor but part will flow back through the the other pump so your probably down to the stock pump volume. If you have two pumps and cut the rail between 2 and 3 and weld them solid and run two complete separate systems this will keep it from happening but if one fails and one doesn't your motor will lean out on two cylinders and die a quick death.

Do yourself a future favor and start watching ebay for an SX or a aeromotive big pump. Either one flows a crap load of fuel and will support a 1000hp and the volume and pressures are off the charts. I just sold an extra one on ebay a few weeks ago for $165 shipped. If you get one of those all you have to do is weld on a sump with a -10 fitting (cost is a fitting and a sheet of steel, maybe 20 bucks) I would say I'd do it but shipping on a fuel tank back and forth would be 60 bucks or more. I'm going to use an SX on mine after the surge tank and I have a 044 feeding the surge tank which is acting as nothing more than a circulating transfer pump


Now your thinking "but there's so many people selling those systems" Doesn't make it right and just because you can draw up a part and have a machine shop cnc cut a mounting fixture doesn't make the designer an engineer.

 

[AnotherNewb]

[quote name-Curtis]If one dies the other want feed all the fuel to the motor but part will flow back through the the other pump



It was my understanding that most fuel pumps have a check valve in them, which is why once you shut your car off you still have pressure on the system.

But never mind that, your logic on running a single pump makes more sense than any other fuel pump discussion I have read.