Hey everyone, I just installed a whole bunch of new parts to the car, FP Red, exedy twin, ams fuel rail, high flow fuel filter (ultimate racing), 1000cc injectors, radiator, radiator hoses, walbro 255 fuel pump.

Here is my problem. There is an insane amount of pressure on the fuel return line...so much as to where it has popped off the fuel pump assembly. This is causing me to have an unstable and shaky idle. I already checked the relay, and the voltage seems to be fine. So I did a little test.

I took off the fuel return line from the fuel pump assembly, and simply put it in a bucket. Boom, the idle is fine and everything seems to run much smoother. The hose isn't rock hard with pressure, and everything seems to be working great.

So, this leads to one conclusion: something in the fuel pump assembly is causing a blockage/restriction in the fuel return line. Has anyone experienced/remedied this? If so, PLEASE contribute and I would GREATLY appreciate it. I really want to get this problem fixed ASAP, i've already been without my car for long enough

Also, would it be a bad idea to bypass the fuel pump assembly and just route the fuel return line directly into the gas tank? Why or why not?

Again, any help is much appreciated. Thanks!

 

I know a guy locally who has the same issue.
He hasnt found a solution as of yet.
Good luck

 

good to see im not the only one with this problem. If anyone knows ANYTHING, please post. I'm going to try and find the part number for the entire OEM fuel pump assembly thing

 

second post ive seen on this

https://www.evolutionm.net/forums/mi...duction-9.html

 

This is the local guy I was referring too.

 

It would be a bad idea. The return sends fuel into the little bucket that surrounds the fuel pump.. that fuel helps cool the pump, and also if you don't allow it to flow in there, will give you lean conditions under acceleration, and turns when you get down to about a half tank

 

I tried searching for it but I can't find it, CBRD or GST posted recently about e85(you didn't say what fuel you were using) breaking down the filter sock around the stock fuel pump and the fragments in turn became stuck in the fuel lines.

 

thanks for trying everyone....anyone else made progress or found a solution?

 

Looks like we have an answer...

http://www.autoblog.com/2009/09/17/n...n-ralliart-an/

 

thanks.....i saw this too. My fuel return is not cracked or anything, i checked it all the way back.

 

does the hb speed pump replace the whole entire white housing that the fuel pump sits in? My guys are looking at it, and there seems to be a pressure relief spring that is supposed to open and close in the fuel return system. This pressure/flow is used to suck or siphon fuel from the other side of the tank to the side with the fuel pump. I think that the problem is, with me at least, is that the spring that opens and closes the little fuel return valve inside the white housing (it's a little white piece) is getting stuck on the "closed" position. This would explain the restriction of flow. So, maybe we just need to get a new little white piece or a new spring, or a whole new fuel pump housing assembly. I've been trying to find the part numbers of the OEM fuel system components, particularly the ones inside the fuel tank, but with no luck.

 

So I installed my Fuelab mini-FPR all AN6 lines goes to a AN4 line to fuel return line...

My pressure reads 75-80 psi (stock fuel pump) read the manual should be 38 psi with vac hose on and 45-50 with vac hose off...

No I tested the fuel pressure with two gauges... both read 75-80 psi...

I have my Aeromotive FPR in my race car which I will take out and check on tuesday if changing FPR's changes anything...

I checked the label on my FPR it should be able to set the pressure to 25-90 psi...

SPEC SHEET

http://www.fuelab.com/index2.php?opt...ory_id=9&pop=1

One theory is that the BOOMBA 90* adapter has a small orfice that goes to a AN6 line, maybe causes a high pressure at the fuel rail...

Dunno... I will investigate... if I switch FPR's and samething continues I will need to start hunting to figure out why...

I checked my idle LTFT and it stays where it was before the new FPR install... I took it for a short drive and my WOT wideband AFR did go richer one point...

 

Man I think all the pressure begins where the fuel return line connects to the white in-tank housing piece that the fuel pump sits on/in. The whole system is like just ridiculous. I think the way it works is the system uses the pressure from the return line to suck gas over from the other side of the tank. If I remember correctly there was a tiny little spring on my housing that I popped and it helped alleviate the pressure. It's been awhile since I've messed with it, but I think you should maybe look at that.

 

Thanks, I will look into it this week when I install my fuel pump.

I thought I was going insane, I check with two gauges, and was about to swap out FPR's...

Seems the problem lies in the tank itself...

 

Where is this little spring you have to remove?