I Think I Have Some Fuel Issues

Jason 302

10 Year Member
Aug 9, 2003
685
71
68
Newark, Ohio
So, quick info on the setup. Mildly built 306, Vortech V3 10/11psi, Aeromotive 340lph in tank pump, used 42lb injectors, Kirban FPR about 12 years old. Stock fuel lines, stock fuel rails. Car dynoed 480/470 at the wheels.

Took the car to the track last night, and started getting some missing in the higher rpms (I would guess above 4000). On my second pass I watched my fuel pressure and watched it go up as the car started to build boost, but it quickly started to drop once I got in the higher rpms. Not wanting to grenade my engine, I called it a night. I do NOT have an air/fuel ratio gauge, but it IS on my list now. On the dyno the car kept a good A/F ratio. Gas tank was also completely full last night.

Does this sound like the stock lines are falling short? I've heard of people having no problems with stock lines and rails at my power level, should I roll the dice and try a new FPR? My current one does have some age on it, not a lot of miles though.

Right now I'm leaning towards a complete fuel system, just not sure which route I want to take.

Option 1: Pro-M hanger keeping the single 340lph and with -6 PTFE fuel lines with Glenns or Behind Bars Racecars rails. I feel like this would be the cheapest option and would be perfect for my power level, however no room for growth and probably not enough for E85 if I wanted to give that a go.
fuel-pump-hanger-1---path_2.jpg


Option 2: Glenns Performance 03/04 Cobra tank setup. Can't really afford this setup right now ($2000+), but seems to be put together really well. Pump hanger has -8 going in and out which I like, also has the ability to run multiple in tank pumps for big power. No fuel filler mods, stock fox one is suppose to work.
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Option 3: On3Performance kit. Cheaper than Glenns, but you get what you pay for. Hanger has -10 going out, -8 coming back. Again, multiple in tank pumps an option. Have to buy a newer style fuel filler and have it modified. One plus is this place is 1/2 hour away, so I could go and pay cash and avoid shipping.
/http://www.on3performance.com/shop/on-3-performance-complete-mustang-fuel-system/

Question: I feel like a single 340 pump is enough for my power level, but can it push enough fuel through a big line like a -10 by itself? I don't want to overbuild it with two big pumps just to have the fuel circulating around and getting hot.

Sorry for the long post, just trying to get some input and provide plenty of info and what I'm thinking. Thanks guys.
 
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could be a number of things.. Who did the tune on the engine and what fuel trim did they establish. Do you have a copy of the dyno sheet or data log. That should contain the AF ratio along the rpm curve. What is your fuel pressure set at? Are the injectors tested or did you ensure they are flowing well. A 12 year olf FPR may be leaking- did you pull the vacuum hose off and smell the line for gas. Does the FPR hold vacuum.
 
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could be a number of things.. Who did the tune on the engine and what fuel trim did they establish. Do you have a copy of the dyno sheet or data log. That should contain the AF ratio along the rpm curve. What is your fuel pressure set at? Are the injectors tested or did you ensure they are flowing well. A 12 year olf FPR may be leaking- did you pull the vacuum hose off and smell the line for gas. Does the FPR hold vacuum.

Brian at Dyno Tune Motorsports, pretty reputable guy. Fuel pressure is set at 40 psi with the line off. I bought the injectors used from a member here on StangNet, I have not smelled the vacumm hose, I will try that later today. The FPR seems to work perfectly fine, pressure drops a little under vacuum, and rises when under boost, up to certain point. It just seems like the engine is using more fuel than the system can provide.
 
from the dyno sheet- and we know that can be manipiulated and not reflect real use on the street or track- your AFR is fine. You have enough fuel pump and your injectors may be maxing out. @jrichker can provide the link for duty cycle formulas for injectors or you can just google it.. It does sound as if an upgrade to the fuel line, hanger is a good idea. @TOOLOW91 as Jeff recently upgraded his
 
Yeah my dyno guy said they were at 90% or somewhere in that area.
from the dyno sheet- and we know that can be manipiulated and not reflect real use on the street or track- your AFR is fine. You have enough fuel pump and your injectors may be maxing out. @jrichker can provide the link for duty cycle formulas for injectors or you can just google it.. It does sound as if an upgrade to the fuel line, hanger is a good idea. @TOOLOW91 as Jeff recently upgraded his

Yeah I'm just wondering what the difference is in fuel demand between doing a 4th gear pull on a dyno and ripping through all 4 gears for 12 straight seconds at the track. The pump was also warm I'm sure, I had just drove the car 30 mins to the track with very short breaks between both runs.
 
Just another thought, even with a mostly full fuel tank, what are the chances of getting aeration from all the sloshing of the fuel when being launched on drag radials. Obviously wouldn't happen staying steady on the dyno. That very high up return tube on the stock hanger is less than desirable.

I've pretty decided to build a fuel system, probably going to go with a setup from Glenns just not sure which to go with. They have a "sleeper tank" setup where a external pump pulls full from a fitting located at the bottom of the tank and returns it at the top where the stock hanger would be. They also have a "hanger" setup that drops in the location of the stock hanger but a external pump pulls and returns the fuel from that location. I have some questions about both setups. Will probably call him next week sometime.

Sleeper tank
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In-tank pickup
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