More Fuel ?
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Senior Member
Joined: Dec 1999
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From: CT.
hey no problem..i like to get many opinions...what i'm not seeing here...are you saying my stock fuel pump isn't supplying the pressure to feed my stock injectors ??that doesn't sound right.... if they are 19#'s they are 19#s and thats it...if i get a better fuel pump the injectors are still only shooting 19#'s ??????? right now i do feel a dead spot at top end in third and o.d...see what i'm not understanding is how a bigger pump would help without changing the injectors...? ......as for this part i'm not saying ANYTHING negative towards either of you ..but..i tend to trust Mike a little more since i know his background a bit better...although he is still a SALESMAN !!!! arrghhh ...hehh hehh....and a damn good one too..thats the problem...!!!
Last edited by ROUSHFAN-1; Nov 16, 2002 at 09:20 AM.
Former Sponsor
Joined: Mar 1998
Posts: 13,385
Likes: 4
From: Virginia
Hi Roushfan-1, et al,
These F-150's are a significantly heavier platform, between their additional weight and the much bigger aero load their fuel needs are more than say, a Mustang at the same power levels. It's not just about the raw power level, it's also about *load*.
Ford generally supplies their vehicles with roughly about a match in fuel pump and fuel injector capacity (it can be skewed a bit either way), but in these heavier trucks, Ford never intended them to be capable of hitting anything significantly over 100 mph, and so you can run shy on fuel pump capacity in these trucks before the 19#'s actually give out. It happens. Don't expect the automaker to always provide more fuel pump than injector (though sometimes they do), or even enough fuel pump capacity for the injector capacity in these big heavy vehicles.
You're right in that at the same rail pressure, a 190 l/hr. fuel pump isn't generally going to increase the flow capacity of those injectors. You would have to raise rail pressure with an adjustable FPR in order to send more fuel pressure to the injector, thus inflating them above their 19# rating. Now if you were to install say, a 255 l/hr. fuel pump, you may well have to install an adjustable FPR just to keep rail pressure down to 39 PSI @ idle, due to the volume of fuel from the giant 255 l/hr. unit.
So yes, your observation about a larger fuel pump not automatically making the injectors flow over their rated capacity is basically correct; though you can reach a point with a big enough fuel pump that it overwhelms the stock fuel rail setup & the adjustable FPR has to be installed just to back the resultant rail pressure down for proper idle & driveability, etc.
At your current power levels in that F-150, you are most likely taxing the limits of your stock fuel pump in 3rd gear & up @ WOT, even though your injectors can be capable of supplying enough fuel for that power level and perhaps a bit more, they can do that if they aren't getting enough fuel *volume* from the fuel pump. Fuel *pressure* has to go hand in hand with fuel *volume*, and they are two separate and different, though "overlapping" aspects of fuel delivery.
The 19# injectors can, **if flowing ideally and pushed to 100%**, as mentioned in our previous post, supply enough fuel for a maximum of 337 hp @ a BSFC of .45 in an 8 cylinder engine. Again, that's under *ideal* circumstances, and at 100% duty cycle. It's never smart to push any injector beyond 90% at the very most, and in reality most formulas and smart tuners use an 80% duty cycle in their calculations for injector sizing, and some will even use a BSFC of .500 for naturally aspirated motors, which would give you 304 hp from a set of 19#'s @ 80% duty cycle. Now 304 hp is a bit more conservative than is needed even in a heavy F-150, so we generally advise if the motor is capable of hitting about 315 hp or so, and more mods are going to be made, or if it's going to be drag raced or the owner is going to do top speed runs, then it's time to go ahead and upgrade to the 24#'s. You can't count on *any* injector flowing a full 100%, and when you actually examine fuel pump ratings & specs, you usually find that to hit their rated numbers takes a full 14+ volts and about 45 PSI rail pressure. All in all, fuel systems need to be looked at sooner in these heavier, taller trucks.
Yes, you *could* stick with the 19#'s & stock fuel pump and just not be able to have it wind out in 3rd gear, but it's prudent to upgrade the fuel pump & injectors as the next upgrades. You could very easily have one, several, or all of those injectors not capable of flowing 90% of their rated flow with 65K miles on them. And you could also be lucky, and be getting much closer to everything they ever had to give, you just never know without flow testing them. The bottom line is, you're certainly close enough, and it's not pulling at higher rpms in 3rd gear, so it's clear that the fuel system upgrades should be done if you are to get the most from all your other mods.
If there is anything you aren't certain about, or want to know more about, or have other questions, etc., please feel free to call us, as always.
Good luck!
These F-150's are a significantly heavier platform, between their additional weight and the much bigger aero load their fuel needs are more than say, a Mustang at the same power levels. It's not just about the raw power level, it's also about *load*.
Ford generally supplies their vehicles with roughly about a match in fuel pump and fuel injector capacity (it can be skewed a bit either way), but in these heavier trucks, Ford never intended them to be capable of hitting anything significantly over 100 mph, and so you can run shy on fuel pump capacity in these trucks before the 19#'s actually give out. It happens. Don't expect the automaker to always provide more fuel pump than injector (though sometimes they do), or even enough fuel pump capacity for the injector capacity in these big heavy vehicles.
You're right in that at the same rail pressure, a 190 l/hr. fuel pump isn't generally going to increase the flow capacity of those injectors. You would have to raise rail pressure with an adjustable FPR in order to send more fuel pressure to the injector, thus inflating them above their 19# rating. Now if you were to install say, a 255 l/hr. fuel pump, you may well have to install an adjustable FPR just to keep rail pressure down to 39 PSI @ idle, due to the volume of fuel from the giant 255 l/hr. unit.
So yes, your observation about a larger fuel pump not automatically making the injectors flow over their rated capacity is basically correct; though you can reach a point with a big enough fuel pump that it overwhelms the stock fuel rail setup & the adjustable FPR has to be installed just to back the resultant rail pressure down for proper idle & driveability, etc.
At your current power levels in that F-150, you are most likely taxing the limits of your stock fuel pump in 3rd gear & up @ WOT, even though your injectors can be capable of supplying enough fuel for that power level and perhaps a bit more, they can do that if they aren't getting enough fuel *volume* from the fuel pump. Fuel *pressure* has to go hand in hand with fuel *volume*, and they are two separate and different, though "overlapping" aspects of fuel delivery.
The 19# injectors can, **if flowing ideally and pushed to 100%**, as mentioned in our previous post, supply enough fuel for a maximum of 337 hp @ a BSFC of .45 in an 8 cylinder engine. Again, that's under *ideal* circumstances, and at 100% duty cycle. It's never smart to push any injector beyond 90% at the very most, and in reality most formulas and smart tuners use an 80% duty cycle in their calculations for injector sizing, and some will even use a BSFC of .500 for naturally aspirated motors, which would give you 304 hp from a set of 19#'s @ 80% duty cycle. Now 304 hp is a bit more conservative than is needed even in a heavy F-150, so we generally advise if the motor is capable of hitting about 315 hp or so, and more mods are going to be made, or if it's going to be drag raced or the owner is going to do top speed runs, then it's time to go ahead and upgrade to the 24#'s. You can't count on *any* injector flowing a full 100%, and when you actually examine fuel pump ratings & specs, you usually find that to hit their rated numbers takes a full 14+ volts and about 45 PSI rail pressure. All in all, fuel systems need to be looked at sooner in these heavier, taller trucks.
Yes, you *could* stick with the 19#'s & stock fuel pump and just not be able to have it wind out in 3rd gear, but it's prudent to upgrade the fuel pump & injectors as the next upgrades. You could very easily have one, several, or all of those injectors not capable of flowing 90% of their rated flow with 65K miles on them. And you could also be lucky, and be getting much closer to everything they ever had to give, you just never know without flow testing them. The bottom line is, you're certainly close enough, and it's not pulling at higher rpms in 3rd gear, so it's clear that the fuel system upgrades should be done if you are to get the most from all your other mods.
If there is anything you aren't certain about, or want to know more about, or have other questions, etc., please feel free to call us, as always.
Good luck!
Senior Member
Joined: Jan 1999
Posts: 7,030
Likes: 3
From: WINDSOR, ONTARIO, CANADA
HI!... I had a ton of fuel problems with my truck last year. Mostly fuel starvation deep into the higher RPM's. Mike and I discussed it several times and this is what we came up with. Installed 24LB injectors, older "98" fuel rail, AREOMOTIVE adjustable fuel regulator, and a reburned SUPERCHIP. I've got my idle fuel pressure set at 38-39PSI and I max out at WOT at 47-48PSI. Since the "99" to current engines don't have a "BOLT-ON" non adjustable fuel regulator, you can't simply remove the factory one and bolt on a aftermarket one. That's where the stock "98" (5.4) fuel rail comes in. IT STILL HAS A NON-ADJUSTABLE fuel regulator but......... it's a bolt on unit. The AREOMOTIVE adjustable fuel regulator simple bolts on to it. Here's a few pics of my set-up :
https://www.f150online.com/galleries...-793-15775.jpg
https://www.f150online.com/galleries...-793-37316.jpg
https://www.f150online.com/galleries...-793-37314.jpg
https://www.f150online.com/galleries...-793-37318.jpg
https://www.f150online.com/galleries...-793-37317.jpg
https://www.f150online.com/galleries...-793-15775.jpg
https://www.f150online.com/galleries...-793-37316.jpg
https://www.f150online.com/galleries...-793-37314.jpg
https://www.f150online.com/galleries...-793-37318.jpg
https://www.f150online.com/galleries...-793-37317.jpg
Thread Starter
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Senior Member
Joined: Dec 1999
Posts: 2,105
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From: CT.
Thanks Neal ....Mike and i shortly discussed your fuel shortage also..I'm not sure where i'm going with my engine yet? since it's a 97 i have a return line and the bolt on regulator i guess?...I think i might want to hit up a dyno to get some real answers of where i'm at ! That zaust set up you have looks kick ***!!!......I can't believe what those long tubes can do!....I don't think i'm going to try to go as far as you have with your 5.4 with my 4.6...because it's pointless i don't even have the p.i. heads..! I think i want to get what i have to an optimum and let it die slowly...it already has 65,000 on it....Then i think it's BIG RE-BUILD time after the big bang.. ..but that's going to take some research...I kinda want to go the route your going because i have no payments either ...Freshen and strengthen the block,P.I. heads ,supercherger.....etc..but ya never know what will happen in the future....It's really cool to see you and Mike going as far as you guys can go on a NON-L. I think some one here needs to step up to be a NON-L tuner and see what people can do with a slightly older mod motor truck.. 
Former Sponsor
Joined: Mar 1998
Posts: 13,385
Likes: 4
From: Virginia
Hi Roushfan-!,
You make a good point indeed, and we too, would like to see more of the non-Lightning F-150's taken to higher performance levels, as it sure can be done.
The bottom line however is speed costs, and sometimes the funds just aren't available to do what we'd all like to do.
Neal's truck is a good example of what can be done by putting the extra effort into each area of modification (read: sweat equity), as for the level of modifications done, that truck is flying. No blower, no ported heads, stock cams & valvesprings, etc., everything he has done has been of the exterior bolt-on variety, & with any traction next time at the track, he shouldn't have any problem dipping into the 13's. At his current power levels since his fuel system, exhaust & torque converter upgrades, he definately needs a set of slicks to get the power to the ground so he doesn't lose a half-second or more just in the first 60 feet!
You really don't have all that many miles on your engine, today the normal service life of these engines is at least 150K miles, and many are getting 175-200K miles from them before rebuilding. Today these engines aren't turning many rpms, and between that and the various advances in metalurgy, lubricants & assembly techniques, we're seeing darn near twice the normal engine service lifespan that we used to up thru the late 80's or so in many cases. So you never know, you may have that engine for a long time & take it a long way before you actually need rebuilding, & good luck with that!
You make a good point indeed, and we too, would like to see more of the non-Lightning F-150's taken to higher performance levels, as it sure can be done.
The bottom line however is speed costs, and sometimes the funds just aren't available to do what we'd all like to do.
Neal's truck is a good example of what can be done by putting the extra effort into each area of modification (read: sweat equity), as for the level of modifications done, that truck is flying. No blower, no ported heads, stock cams & valvesprings, etc., everything he has done has been of the exterior bolt-on variety, & with any traction next time at the track, he shouldn't have any problem dipping into the 13's. At his current power levels since his fuel system, exhaust & torque converter upgrades, he definately needs a set of slicks to get the power to the ground so he doesn't lose a half-second or more just in the first 60 feet!
You really don't have all that many miles on your engine, today the normal service life of these engines is at least 150K miles, and many are getting 175-200K miles from them before rebuilding. Today these engines aren't turning many rpms, and between that and the various advances in metalurgy, lubricants & assembly techniques, we're seeing darn near twice the normal engine service lifespan that we used to up thru the late 80's or so in many cases. So you never know, you may have that engine for a long time & take it a long way before you actually need rebuilding, & good luck with that!