[tvsn94]

this is an addition to an old thread i started concerning fuel delivery problems.
I have recently replaced the stock system ( w/ aeromotive 340 intank pump). i was having bad low speed / cruise AF problems . WOT was fine. it started when outside temps were 80+ and driving 20-30min.
I decided the solution was bigger lines. I purchased a Glenns Performance 1000hp system with pick up tube in stock tank. I was assured this was completely street-able. It consist of -10 suction to twin external 255 Walbro pumps . -8 supply and -6 return. Glenns fuel rails , filter and regulator.
this has been a big improvement so far. BUT still getting pump cavitation in 100degree temps and a surge in idle fuel press ( about 2 lbs) this is worse around a 1/2 tank and less.
I didnt want to re-invent the wheel, so went with a pro. but still have found/heard no sure fix for this problem, It just cant be only me. has anybody whooped this?
I sure need some input guys.

[LeadHead]

If you've having temperature related fuel system troubles, throwing way more pump at it than you need is only going to make it worse. You're going to get excessive fuel heating.

[tvsn94]

this is for anybody that may encounter the problems i have had, I never found ANYBODY that could tell me a fix. It now seems that I have things under control.
as most know the mustang's have a box in the tank that helps control slosh. the return goes back to this box either above the tank floor several inches ( ala factory ) or all the way to the bottom ( Glenns Performance, and maybe a few others). something I have suspected was that the tremendous re-circulation rate of the large pumps aerates / foams the fuel. this showed up worse as the fuel level drops. the factory setup would begin reducing the idle/low speed AFR around 1/2 tank. the Glenns setup would do same about 1/4 tank. this lowering of AFR would be typically 20-25%. Very troubling for a Turbo car. causing all kind or drive-ability problems and all tuning efforts would result in very rich conditions after a fill up or a fresh start up. also I noticed that the tank would be under much higher press. I fixed the vent , all better now. I figured the press came from the air trapped in the high press fuel system and breaking out past the regulator , like a coke releasing CO2.
the solution was to bend the return tube to shoot the fuel OVER the top of the box, sound too simple and it was.
Point is that I have spent WAAAY to much time and $$ chasing this problem. I want to get this out there for the next poor SOB that gets into this situation.

[decipha]

you got a pic?

[EDS50]

I went back to a stock type of fuel system and use the Pro-M fuel pump hanger with a Walbro 450lph pump and Walbro gsl392 Inline pump which helped eliminate the cavitation issues I was having with a sumped tank and Weldon 2025.

http://www.promracing.com/home-page-bes ... tangs.html

[tvsn94]

sorry no picts. but its pretty simple. the Glenns in tank pickup uses a -10 suction and a -8 return that goes right too the bottom of the tank. they are tack welded together for rigidity. I cut the weld and used a 1/2" bender to curve the tube up 90 degrees. had to trim about 1" off to get it back through the tank opening,
I believe that shooting all the return fuel as far away from the suction is the solution. one thing i notice is that at near empty ( around 2 gal left) I get short spurts of leanout during low speed driving . this correct itself when not turning or start/stop. this i can live with and just go filler up.
it seems apparent that if you could slow down or spread out the return to the box it would be ideal, Maybe some tank foam?

[EDS50]

Tank foam is really just to control fuel slosh in fuel cells. Everyone rips the foam out these days because the ethanol blended pump gas breaks down the foam and clogs up the fuel system.