WARNING / HOW TO: Fuel Line Return (High Pressure)
Mar 14, 2010, 10:05 PM
#18
Okay, I did more research. I think I came with a severe issue.
If you drill this hole out to 5/16" it will be way too large.
It will cause not enough pressure to be driverted to the hole that connects to the blue connector on the fuel assembly holder. So what does this mean? It means that blue connector causes a "swirling effect"/"venturi pump effect" which will not suck fuel the other side of the tank. Meaning you will run out of fuel 1/4th to 1/3" tank of fuel left. Scary on the highway.
The porting does not effect this effect. However, removing that restrictor does.
The fix is to get some aluminum rod. cut about .125" off drill a 5/65th" hole in the middle, then start filing away the sides to make it fit the hole. Luckily if you used a 5/16th earlier, it leaves a step, which now inturn you can insert the restrictor pill and press it in. Solves the issue and restores the venturi pump effect intank.
If you drill this hole out to 5/16" it will be way too large.
It will cause not enough pressure to be driverted to the hole that connects to the blue connector on the fuel assembly holder. So what does this mean? It means that blue connector causes a "swirling effect"/"venturi pump effect" which will not suck fuel the other side of the tank. Meaning you will run out of fuel 1/4th to 1/3" tank of fuel left. Scary on the highway.
The porting does not effect this effect. However, removing that restrictor does.
The fix is to get some aluminum rod. cut about .125" off drill a 5/65th" hole in the middle, then start filing away the sides to make it fit the hole. Luckily if you used a 5/16th earlier, it leaves a step, which now inturn you can insert the restrictor pill and press it in. Solves the issue and restores the venturi pump effect intank.
May 14, 2010, 10:57 PM
#19
Just to follow up on this... I got my fuel pressure regulator hooked up today.
When I first hooked it up I was running 100PSI!
No matter what I did to the FPR it wouldn't go lower.
I pulled the fuel pump housing again and pulled the little filter. It was completely clogged (likely with stuff from the fuel pump sock). Pulled that and drilled out the return orifice to 5/64. Now my base fuel pressure is 48ish which I'm fine with.
Now I'm guessing I get to retune! Fun stuff!
When I first hooked it up I was running 100PSI!
No matter what I did to the FPR it wouldn't go lower.
I pulled the fuel pump housing again and pulled the little filter. It was completely clogged (likely with stuff from the fuel pump sock). Pulled that and drilled out the return orifice to 5/64. Now my base fuel pressure is 48ish which I'm fine with.
Now I'm guessing I get to retune! Fun stuff!
May 16, 2010, 07:59 AM
#20
Just to follow up on this... I got my fuel pressure regulator hooked up today.
When I first hooked it up I was running 100PSI!
No matter what I did to the FPR it wouldn't go lower.
I pulled the fuel pump housing again and pulled the little filter. It was completely clogged (likely with stuff from the fuel pump sock). Pulled that and drilled out the return orifice to 5/64. Now my base fuel pressure is 48ish which I'm fine with.
Now I'm guessing I get to retune! Fun stuff!
When I first hooked it up I was running 100PSI!
No matter what I did to the FPR it wouldn't go lower.
I pulled the fuel pump housing again and pulled the little filter. It was completely clogged (likely with stuff from the fuel pump sock). Pulled that and drilled out the return orifice to 5/64. Now my base fuel pressure is 48ish which I'm fine with.
Now I'm guessing I get to retune! Fun stuff!
Thanks for posting up goofy.
May 16, 2010, 08:46 AM
#21
ya, definitely need to retune. The car is expecting 100psi+, so it's running super lean. I'm seeing STFT of 20%+ (after resetting the trims). Got P0171 (system lean) so I'm having to be super granny around town 
.
I bet this explains why when I was trying to tune it myself a few months ago I couldn't get it to lean up. No matter how much fuel I added in the map, under boost it would always stay at a certain AFR (like 11.8, remember I'm on E85). I wonder if there's more powah in there
I'm scheduled for a retune on Thursday @ Cobb Plano, so we'll see what comes out of it.
.I bet this explains why when I was trying to tune it myself a few months ago I couldn't get it to lean up. No matter how much fuel I added in the map, under boost it would always stay at a certain AFR (like 11.8, remember I'm on E85). I wonder if there's more powah in there
I'm scheduled for a retune on Thursday @ Cobb Plano, so we'll see what comes out of it.
May 17, 2010, 05:28 AM
#23
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On EDM cars this little fuel filter is not fitted in return pipe.
Upgrading the in tank pump to higher flow doesn't alter fuel press.
No drilling needed.
Does the USDM cars have map sensor for the fuel tank?
Upgrading the in tank pump to higher flow doesn't alter fuel press.
No drilling needed.
Does the USDM cars have map sensor for the fuel tank?
May 17, 2010, 07:13 AM
#25
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It has been about 6 years since I upgraded mine, but I think I used 3/8" brake line to replace what was there stock. NO drilling required.
May 17, 2010, 07:58 AM
#26
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You could email him. He replaces the return line hose but I assume it is connecting to the same return within the housing.
As long as you have a gauge you can monitor this. I assume that running those pressures would make the car difficult to tune and probably burn up the pump sooner than later.
As long as you have a gauge you can monitor this. I assume that running those pressures would make the car difficult to tune and probably burn up the pump sooner than later.
Mar 9, 2011, 11:07 PM
#27
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I had the same 100psi fuel pressure issue when upgrading to a aeromotive FPR, -6an line, fuel rail ect.. had to go from -6an to -4an for the return and the pressure was soo high it started leaking at the fuel pump housing. Now that I hear about the fuel return filter im gonna see if the evo 8 has one also. This whole time I thought maybe the larger feed lines and then the small return was causing too much back pressure.
Mar 10, 2011, 08:37 AM
#28
I had the same 100psi fuel pressure issue when upgrading to a aeromotive FPR, -6an line, fuel rail ect.. had to go from -6an to -4an for the return and the pressure was soo high it started leaking at the fuel pump housing. Now that I hear about the fuel return filter im gonna see if the evo 8 has one also. This whole time I thought maybe the larger feed lines and then the small return was causing too much back pressure.
Mar 10, 2011, 11:39 AM
#29
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Good to know man thanks! Last night I had another stock evo8 housing laying around so I took the T fitting off and used a 1/4 drill bit not thinking about the Bernoulli effect so after I took the pump out of the car and inspected the T fitting and it had some weird gunk stuck in it so I think ill take it back out again and mod that one with the proper 5/64s drill bit and install my aeromotive fpr, 6an lines, fuel rail and 6an to 4an return line.
Mar 10, 2011, 01:45 PM
#30
Good to know man thanks! Last night I had another stock evo8 housing laying around so I took the T fitting off and used a 1/4 drill bit not thinking about the Bernoulli effect so after I took the pump out of the car and inspected the T fitting and it had some weird gunk stuck in it so I think ill take it back out again and mod that one with the proper 5/64s drill bit and install my aeromotive fpr, 6an lines, fuel rail and 6an to 4an return line.
Yeah if you go too big, you loose the Venturi effect, which sucks fuel from other side of the tank.