Fuel Woes in my Mod Fox

[jonb347]

So I am running the following setup in my mod fox.

Stock fox tank with 255 lph pump
Return system from fox
return style stock rails that fit on the dohc setup but has a FIXED stock style regulator
bypassed the fpdm pump is powered all the time

thing runs like a champ most of the time, but sometimes if the wind blows the wrong way and its between a certain temperature and someone spits the wrong direction, it dies off and stalls on me when im leaving a stop sign.

im sure this could be fixed with an adjustable regulator, but the regulator is fixed.

should i just swap over the tank and fuel lines and hook up the frps and fpdm again? thanks!

 

[cj428mach]

What are you doing for a tune? if you go into the tune and tell it the car is a return system and runs XX pressure you won't have any issues. Its no different than my 03 with a return setup, I just cranked up the pressure to 50psi and told the computer I was doing so in the tune.

Also what makes you think its a fuel issue anyways?

 

[MalcolmV8]

Also what makes you think its a fuel issue anyways?

+1. Could be just about anything. What data logging or info have you gathered that's led you to believe it's a fuel issue?

 

[jonb347]

i tuned it. i havent been able to log any info since it only does it sometimes. its basically dies off like its not getting enough gas. starts right back up. and is fine, just have to do it right. very occassionally it will die when you push the clutch in and coast to a stop sign. im going to play around with fuel pressure in the tune tonight when i get it back i think. hood is getting clearanced at body shop right now. this is my build

http://www.svtperformance.com/forums/showthread.php?992497-ModFox-Eaton-Swap-IRS-Build

 

[cj428mach]

I take it you made all the necessary changes in your tune to go return fuel system? Also you set the fuel pressure in your tune to match what you're running correct?

It definitely sounds like a tuning issue, i'm not sure its even related to your fuel system.

 

[MalcolmV8]

Clutch in and coasting to a stop is also a tuning issue. In fact a lot of 03s had that issue bone stock and Ford reflashed with a tune revision to fix back when they first came out.

 

[jonb347]

that only happens sometimes. usually it is when you give it just a little bit of gas to bring the revs up before letting the clutch out. if you do it slowly its fine, if you do it quickly as if you were driving normal it dies. sometimes its totally fine.

tune is set to return system with stock fuel pressure...i just checked with a gauge to verify it is running at 39 psi at idle which is stock fuel pressure i believe

 

[cj428mach]

So you're running the Mach 1 computer and strategy? After looking at your swap I'd think a bone stock Cobra tune set to return would take care of most of your problems as your build didn't look like it varied much from there.

 

[MalcolmV8]

tune is set to return system with stock fuel pressure...i just checked with a gauge to verify it is running at 39 psi at idle which is stock fuel pressure i believe

Did you pull the vacuum/boost reference from your regulator when checking fuel pressure? I always set base pressure with the engine off and pumps on.

 

[jonb347]

mach 1 computer. tuned for blower with return system at stock psi. does the mach 1 have a different base fuel psi than the cobra? ford manual says 35-70psi lol. i can't set my base pressure as the regulator is not adjustable, hence the issue. ill check psi with pump running and motor off in a minute here

 

[MalcolmV8]

mach 1 computer. tuned for blower with return system at stock psi. does the mach 1 have a different base fuel psi than the cobra? ford manual says 35-70psi lol. i can't set my base pressure as the regulator is not adjustable, hence the issue. ill check psi with pump running and motor off in a minute here

You can set the base fuel pressure to what ever you want. Or in your case work with what ever your pre-fixed base pressure is. You just have to set the tune accordingly.

 

[jonb347]

okay with car off and pump running its running 41psi. when idling its 39psi. at idle with the vacuum unhooked it goes to 42-43 at idle. tune is set for stock, should i adjust it? by the way for now im using sniper tuning, which i love but i know its not a dynotune. it allows me to disable pats and whatnot for my car until i get everything sorted out. the fuel pressure goes stock, +1, +2, +3 etc which is why im not sure where to set it.

 

[MalcolmV8]

okay with car off and pump running its running 41psi. when idling its 39psi. at idle with the vacuum unhooked it goes to 42-43 at idle. tune is set for stock, should i adjust it? by the way for now im using sniper tuning, which i love but i know its not a dynotune. it allows me to disable pats and whatnot for my car until i get everything sorted out. the fuel pressure goes stock, +1, +2, +3 etc which is why im not sure where to set it.

I tune with SCT's Pro Racer Package myself. Sorry not familiar with the sniper tuning so can't really help with that part of it.

 

[jonb347]

thats fine, im just wondering your thoughts on what the fuel pressure runs vs. what it was stock

 

[MalcolmV8]

39 PSI should be stock. Yours is fairly close. Even if it was a little off it doesn't cause any of the issues you're seeing. I really don't think your two issues you described are related to fuel pressure.

 

[jonb347]

I just put two and two together that it seems worse the hotter it gets. like a nice crisp day and its fine.