Sorry, I'm sure this has been covered in depth, but my searches have maybe not turned up all the info I need.

I'm looking for advice on what to do for my fuel system next to support my build. I got my FP Red rebuilt and back on the car this week and when it went to get tuned it was running out of fuel around 28psi of boost on e85.

I'm still on the stock fuel rail, fpr, lines, FIC 1650 high-z injectors, and using a Walbro 450 that isn't hardwired yet.

Would just doing the hardwired upgrade mrfred has outlined here: https://www.evolutionm.net/forums/ev...e-circuit.html be enough to maximize the Red or do I need to upgrade the fuel rail and any other parts?

 

I have a stainless steel red @30 psi onn e85.
fic 1450cc
wally 450
-6 stm feed line
stm 14 volt rewire with spoolin up hobbs switch
Kept factory high low voltage to pump, just tapped into power and ground wires so it receives 14 volts when hobbs is activated.
Stock rail and fpr. injector duty cycle 90 ish.

I would suggest trying the wally 400 it looks to be a cleaner more fit install since the 450 requires a ghetto rig and have to chop fuel pump feed barb and also chop fuel pump hangar and then add a worm clamp to hold it all together.

The 450 works but the 400 seems to be just a tad longer then the wally 255 and will require less hacking.

Stock rail and fpr is plenty unless you want to raise base pressure for a situation were your duty cycle is too high.

I modded my fuel system in tid bits. First i did the pump and ran it out of fuel. Then i did the feed line and still needed fuel so i ended up adding the 14 volt rewire and have plenty of fuel up top.

Add the pump and see were you end up. If need more fuel you can even just do a rail and regulator to raise base fuel pressure which will give you more injector wiggle room.

Theres a few ways to work around fuel supply.

 

You're NOT going to diagnose it without a fuel pressure gauge.


Then you'll know the pressure isn't stable.


Guesswork never works and ends up with broken engine.

 

OP I'm in the same boat as you. Just picked up an FP Red myself, have 1200cc injectors, a 450 (not rewired - yet) pump and was running out of fuel around 27-28psi.

I bought a -6 fuel feed line kit from STM and I'm able to run 30 psi now @ ~90% IDC at 11.5AFR with no AFR stability issues.

I plan on turning up the boost to 32-33 PSI soon so I'm probably going to rewire the 450. As I understand mrfred's posts, if you rewire a 450 then an upgraded return line is necessary so I think I'll probably try using the stock feed line as a return line and see if I have FPR overrun issues.

I'm curious to know what you find.

 

you can keep the return line. Just drill out the siphon. with a 9/64 drill bit or 1/8 will work i believe

 

I ended up speaking to Connor over at STM and was recommended to hardwire the pump along with adding a fuel pressure regulator. I'm going to try that and maybe a rail and see if that gets me the fuel I need.

I didn't know about needing to drill out the siphon or upgrade the return. I'll have to check it out once I'm able to see what kind of pressure the system has.

 

Don't do a hardwire, do a Hi/Lo voltage rewire as described here:


https://www.evolutionm.net/forums/ev...l#post11183124


You do that, and drill your siphon to 9/64 and you'll be fine, no need to buy an FPR. You're running out of fuel because the pump can't draw enough amps through the stock wiring.


DO NOT list to RightSaid Fred. He's spewing bad info as usual.

 

This might be a dumb question - if you don't do a hardwire, are you going to deal with brief rich conditions when the hardwire does kick in and give the pump more amps?

I'm wondering if doing a hardwire with an upgraded (and drilled siphon) return line and maybe an FPR might keep AFRs more consistent. Would like to know your thoughts

 

I have done the hi/lo voltage rewire with hobbs switch on several cars. It does not cause an issue with briefly going rich. There is no reason to buy an FPR.

 

Sorry, I didn't mean I'd only hardwire the pump. I was planning on keeping the factory low voltage circuit and then going directly to the battery for the high voltage circuit as laid out in that post.

With that method I really wouldn't end up needing the aftermarket fpr?

 

A proper pressure gauge doesn't tell lies.
You NEED a better FPR.


Also..............an indicated 90% IDC is only about 75% real IDC.
But you won't know.

Yours blew up.
The end result is always the same when you get it wrong.

 

If you have ever tuned anything, you would know it's fairly to tell when you're out of fuel pump. You add fuel in the map a given %, IDC goes up, but your AFR doesn't correct the amount it should have (roughly the same percentage as what you added to the map).


But here you are, spewing bad info as usual.

 

Software doesn't work on broken hardware so it's essential to confirm the hardware first.
A good pressure gauge doesn't tell lies.



Just to go over the maths for the OP........
A walbro 450 should flow about 6 litres per min at 70PSI and 13.5 volts.

But in the car it will flow a bit less. The volts will be a bit less?
How much will it flow in the car?

A set of 4 1650 injectors will flow 6.6 litres per min at 100% IDC?
Or will they?
No, not with E85, they'll flow about 10% less. Maybe 20% less.
But you won't know that either. Not unless you've flow tested injectors yourself using both ethanol and petrol.
But at an indicated 90% IDC on a logger, it's a true 75% IDC......you'll be flowing about 4 litres per min.


How will you know?


Guesswork?

 

We've all heard Fred's fuel pressure sermon, just ignore him

 

Unless Im missing something why would flow go down with e85? Not like youre trying to pump molasses through them...