Fuel Need Some Help And Advice

I can't offer advice but I have a similar problem.

Distributors and tfi modules have been extremely picky for me. The only ones I have found for me that works is the mallory tfi distributor and module.

If I put in a stock dis and module, module stops working shortly after the car starts, same thing with the 3 or 4 tfi modules I have. I've tried the 3 or 4 modules on the mallory distributor and none of them work for more than a few minutes and had it fry a ignition coil.

I'm stuck using the mallory dis with the tfi that came with the dis.


Can't explain it. Same thing happens if I swap them around on a completly different car.

I have the same pump as you. I don't have that issue that I'm aware of. When I replaced the pump I replaced the whole bracket the pump is on. I know there are some check valves and things on the bracket, but again, I'm not sure if thats the issue. However I do run a 190 lph pump on stock lines.

How much power are you running that requires a 190 LPH pump?
Read below and pay particular attention to my comments at the bottom of the tech note.


Copied from the FORD RACING PERFORMANCE PARTS catalog:

PROPERLY SIZING FUEL SYSTEM COMPONENTS

Fuel Pumps
The following information is presented assuming the above information has been taken into consideration regarding BSFC, fuel pressure and specific gravity of the fuel being used. Most fuel pumps for electronic fuel injection are rated for flow at 12 volts @ 40 PSI. Most vehicle charging systems operate anywhere from 13.2v to 14.4v. The more voltage you feed a pump, the faster it spins which, obviously, will put out more fuel. Rating a fuel pump at 12 volts then, should offer a fairly conservative fuel flow rating allowing you to safely determine the pump’s ability to supply an adequate amount of fuel for a particular application.

As previously mentioned, engines actually require a certain WEIGHT of fuel, NOT a certain VOLUME of fuel per horsepower. This can offer a bit of confusion since most fuel pumps are rated by volume, and not by weight. To determine the proper fuel pump required, a few mathematical conversions will need to be performed using the following information. There are 3.785 liters in 1 US Gallon. 1 gallon of gasoline (.72 specific gravity @ 65° F) weighs 6.009 LBS.

To be certain that the fuel pump is not run to its very limit, which could potentially be dangerous to the engine, multiply the final output of the fuel pump by 0.9 to determine the capacity of the fuel pump at 90% output. This should offer plenty of ‘cushion’ as to the overall “horsepower capacity” of the fuel pump.

To determine the overall capacity of a fuel pump rated in liters, use the additional following conversions:
(Liters per Hour) / 3.785 = Gallons
Multiply by 6.009 = LBS/HR
Multiply by 0.9 = Capacity at 90%
Divide by BSFC = Horsepower Capacity
So for a 110 LPH fuel pump:
110 / 3.785 = 29.06 Gallons
29.06 x 6.009 = 174.62 LBS/HR
174.62 x 0.9 = 157 LBS/HR @ 90% Capacity
157 / 0.5 = 314 HP safe naturally aspirated “Horsepower Capacity”

Safe “Horsepower Capacity” @ 40 PSI with 12 Volts
60 Liter Pump = 95 LB/HR X .9 = 86 LB/HR, Safe for 170 naturally aspirated Horsepower
88 Liter Pump = 140 LB/HR X .9 = 126 LB/HR, Safe for 250 naturally aspirated Horsepower
110 Liter Pump = 175 LB/HR X .9 = 157 LB/HR, Safe for 315 naturally aspirated Horsepower
155 Liter Pump = 246 LB/HR X .9 = 221 LB/HR, Safe for 440 naturally aspirated Horsepower
190 Liter Pump = 302 LB/HR X .9 = 271 LB/HR, Safe for 540 naturally aspirated Horsepower
255 Liter Pump = 405 LB/HR X .9 = 364 LB/HR, Safe for 700 naturally aspirated Horsepower

Note: For forced induction engines, the above power levels will be reduced because as the pressure required by the pump increases, the flow decreases. In order to do proper fuel pump sizing, a fuel pump map is required, which shows flow rate versus delivery pressure.

That is, a 255 liter per hour pump at 40 PSI may only supply 200 liters per hour at 58 PSI (40 PSI plus 18 lbs of boost). Additionally, if you use a fuel line that is not large enough, this can result in decreased fuel volume due to the pressure drop across the fuel feed line: 255 LPH at the pump may only result in 225 LPH at the fuel rail.


My Comments:

A lot of people oversize the fuel pump by buying a 255LPH pump thinking that the fuel pump regulator will just pass the excess gas back to the tank. It does, but… Did you ever consider that circulating the fuel around as a 255 LPH pump does will cause the gas to pickup engine heat? What happens to hot gasoline? It boils off or pressurizes the fuel tank! With most of the 5.0 Mustangs having the carbon canister removed or disabled, the car stinks like gas, and the gas mileage drops since the hot fuel evaporates away into the air.

I had a persistent problem with overheating and aerating the fuel with a 190lph pump...for YEARS. Not thinking it could be the pump, I insulated every line I could find, I shielded the tank, I wrapped the tailpipes, I went to dumps and back, and it wasn't until the pump started to die that I thought maybe I should go smaller. So I installed a 155lph pump and the problem is almost completely cured.

Two people have come to the same conclusion; try a smaller fuel pump.

A 155 LPH fuel pump should be more than enough for your engine. I would peg your HP closer to 310-325 at the flywheel

What are the symptoms of fuel that is being aerated?

Now you guys worry me because I have a 190, but I have not had any drivability issues. No stumbling, hesitation or anything of the sort.

I shouldn't even post this...but I've ran 255 pumps with even less horsepower than 325fwhp and never experienced this problem. Not trying to muddy the water or start an issue, just stating my experience. I don't know why a "heated fuel issue" would lead to blown tfi modules. Sounds like a short somewhere to me. Unless I'm just confused? Which is possible lol. J is a great resource on here and has tons of valuable experience/info posted on this site. I just don't believe this is the problem but a smaller pump isn't a major investment to troubleshoot the issue. Good luck.

jAEded said:

What are the symptoms of fuel that is being aerated?

Click to expand...

You'll see fuel pressure fluctuations from the air in the line.

what is the secret of 45 minutes? Check your fuel pressure regulator.

@88gt40,
@A5literMan
The clue is how the car is used; the OP said autocross. Autocross takes a toil on brakes, transmission and engine . The engine runs up and down the RPM range and the body rolls, twists and dives. What does that do to the fuel in the fuel tank? It sloshes around a lot. It is already heated from being recirculated to the hot engine and then back to the fuel tank. The sloshing around causes the fuel to vaporize more than just straight line driving with some gentle curves..