Interesting fuel pressure regulator thread

[tiffo60]

This is on nloc and i know there are a couple of guys here having some trouble with there fuel systems

http://www.nloc.net/vbforum/showthread.php?t=149849

but what i found that looked interesting was James's(RWTD) respone to the question and seems like an easy way to fix our problems

The returnless fuel system style Mustangs use a FPDM (fuel pump driver module) and a FRPS (fuel rail pressure sensor) to control fuel delivery. This system is able to vary the voltage however it wants. All Lightnings use return style like the older vehicles, but they have a resistor that varies the voltage to the pumps from either a constant 6v (PT) or 12v (WOT). As the article states above, you cannot safely run a returnless style fuel pump in a return style system, nor vice versa, otherwise they will burn up. For the Lightnings, you need to get an adjustable fuel pressure regulator, and then get rid of the "resistor" module. The resistor module overheats with the 255lph pumps, and causes drivability quirks, and dangerously lean WOT tip-in issues.

The resistor module is up front in front of the IC pump. It's a white porcelain looking device (it gets REAL hot once the truck is running, especially with the 255lph pumps, so be careful). You just take the wires going to it, cut them, and then put male/female spade connectors on the end, and plug them into one another. This will run the pumps at a constant 12v, which is where they are designed to run from Walbro. You then take the adjustable regulator and back the pressure down to 39 psi at idle, with the vacuum line off. Then put the vacuum line back on. You will now have true fuel pressure like all Fords should have, your pumps will run at a constant 12v, and also the regulator will add pressure based on boost (1:1 ratio).

This is how we do all Lightnings now. YOU DO NOT HAVE TO SWITCH TO THE '97 RAILS! You can get the proper regulator here:

http://www.southfloridapulleyhq.com/SFPH/lightning/lightning_products_fuel_system.htm

[L-Fever]

Very interesting!

[wesman]

Screw it, I'll try it....what could happen??? I go lean and burn some plugs??? Oh wait, that's happening now :throw:

Once I get back in town the L is at the top of th elist as soon as I pick the Viper up from Austin.

--wes

[Ohmsby]

maybe another piece of the puzzle I am subscribing

[Ohmsby]

I am up at the shop in Denton crawled under the Gen II and it has this mod already so maybe there is something to it. Work was done @ JLP

[Beaudee]

.Would this be a consideration with a 4LB lower pulley mod.:confused:

[Mark #2]

I am up at the shop in Denton crawled under the Gen II and it has this mod already so maybe there is something to it. Work was done @ JLP

So detail oriented me again
Resistor is removed?
Wires are tied together?
and you have the fuel pressure regulator described...correct?

[Ohmsby]

So detail oriented me again
Resistor is removed?
Wires are tied together?
and you have the fuel pressure regulator described...correct?

looks like it I need to jack it up and get the full view but for sure I have the regulator and the wires are spliced fuel pressure is 38-40 on gauge with the ignition on and motor off

Need to Jack it up to see if the resistor is deleted my dainty physique :cool: does not fit all the way under the dropped L so I had a limited view

[charlie]

OK I'm missing something here.

I understand how the pumps work normally. 6 VDC normal driving------
12 VDC Smashing the gas... Bla bla bla

What I don't get is how the pressure is regulated with the resistor by passed. The pumps would be running full pressure all the time. So how do you get the pressure down when driving normal? Is the mechanical pressure regulator controlled with vacuum?

Thanks
Charlie

[Mark #2]

looks like it I need to jack it up and get the full view but for sure I have the regulator and the wires are spliced fuel pressure is 38-40 on gauge with the ignition on and motor off

Need to Jack it up to see if the resistor is deleted my dainty physique :cool: does not fit all the way under the dropped L so I had a limited view

I can't get under my truck either, with only 6 inches of front clearance nothing on my body fits below it.;)

I think taking the resistor out with 255 pumps is a good idea, let the pumps run constant at a 12 volt rate and modulate with the regulator sounds like the correct thing to me.
One variable boost versus two voltage and boost.

[L-Fever]

OK I'm missing something here.

I understand how the pumps work normally. 6 VDC normal driving------
12 VDC Smashing the gas... Bla bla bla

What I don't get is how the pressure is regulated with the resistor by passed. The pumps would be running full pressure all the time. So how do you get the pressure down when driving normal? Is the mechanical pressure regulator controlled with vacuum?

Thanks
Charlie

My understanding is that the pumps would be running at 12v and full pressure all the time with the pressure regulator sending the excess fuel back to the tank/s. To me this would be a good setup for a race truck and not for a daily, driver even with upgraded walbro fuel pumps.IMO

[Mark #2]

Is the mechanical pressure regulator controlled with vacuum?

Thanks
Charlie
I believe that is how it works.

[SILVER2000SVT]

My understanding is that the pumps would be running at 12v and full pressure all the time with the pressure regulator sending the excess fuel back to the tank/s. To me this would be a good setup for a race truck and not for a daily, driver even with upgraded walbro fuel pumps.IMO

This makes sense, but why would you need to add an adjustable regulator if we already have a boost sensitive regulator. I haven't looked, but is there a mechanical regulator already on our trucks? If so , where?

Since the warbro pumps require 12V all the time I had an idea. After reading these posts I could easily add a pressure sensor and have one pump running all the time then turn the second pump on with a relay when you hit positive pressure on your boost. (Ford basically does this by cutting the voltage in half, I'm just suggestion only running one pump instead) That way during normal driving and idle conditions you don't have the additional energy and heat being added by unnecessary flow that just ends up returning to the tank by the second pump. One pump should be more than adequate for non-boost applications. Obviously this would require a check valve on the output of the non-full time pump to keep from back feeding.

[Ohmsby]

anything to increase my MPG......

[Mark #2]

My understanding is that the pumps would be running at 12v and full pressure all the time with the pressure regulator sending the excess fuel back to the tank/s. To me this would be a good setup for a race truck and not for a daily, driver even with upgraded walbro fuel pumps.IMO

This might heat the fuel in the tank during daily driving as you are recycling it more often through the fuel rails in the hot engine compartment, but how long is it there, and what is the thermal mass of the gas in the tank and it's thermal loss to the environment?

No answers, No data.;)

[Ohmsby]

This might heat the fuel in the tank during daily driving as you are recycling it more often through the fuel rails in the hot engine compartment, but how long is it there, and what is the thermal mass of the gas in the tank and it's thermal loss to the environment?

No answers, No data.;)


6

[Mark #2]

6
What does that mean:confused: :confused:

[WA 2 FST]

.Would this be a consideration with a 4LB lower pulley mod.:confused:

If that's about all you have, no. Untiil you're probably ~500rwhp, I can't imagine this being necessary.

[L8 APEX]

Screw it, I'll try it....what could happen??? I go lean and burn some plugs??? Oh wait, that's happening now :throw:

Once I get back in town the L is at the top of th elist as soon as I pick the Viper up from Austin.

--wes
I switched your fuel pump driver to single speed vs. two speed in the tune. That setting is supposed to run on the high speed 12V relay all of the time. Another way of reaching the same end result.

[L-Fever]

This might heat the fuel in the tank during daily driving as you are recycling it more often through the fuel rails in the hot engine compartment, but how long is it there, and what is the thermal mass of the gas in the tank and it's thermal loss to the environment?

No answers, No data.;)

These are great questions!

[Ohmsby]

I switched your fuel pump driver to single speed vs. two speed in the tune. That setting is supposed to run on the high speed 12V relay all of the time. Another way of reaching the same end result.

Would you still need to remove the resistor? Any thoughts on this Heating the fuel?

[Beaudee]

If that's about all you have, no. Untiil you're probably ~500rwhp, I can't imagine this being necessary.

Ya that was what i was thinkin.Thanks Wes!This is a great thread tho.

[L-Fever]

Would you still need to remove the resistor? Any thoughts on this Heating the fuel?

I think this is why it's a good mod for a race truck. It would be nice to have it both ways. How hot does the fuel,tank, and rails get while sitting at a stop light in the middle of summer or on a long drive? Is it time for a fuel controller setup of some type? or a switch to bypass the resistor for the track? or? I think going to stay with my stock resistor setup for now.

[Beaudee]

I think this is why it's a good mod for a race truck. It would be nice to have it both ways. How hot does the fuel,tank, and rails get while sitting at a stop light in the middle of summer or on a long drive? Is it time for a fuel controller setup of some type? or a switch to bypass the resistor for the track? or? I think going to stay with my stock resistor setup for now.

I dont know what the flow is on this system,but hydraulically speeking running fluid over a relief valve heats oil pretty fast.Might consider keepin the tank above half.

[L8 APEX]

Would you still need to remove the resistor? Any thoughts on this Heating the fuel?
There are two relays to the fuel pumps. One goes through the resistor for low speed and other goes straight to the pumps for WOT. Changing the pump type in the tune makes it run the high speed relay all the time. I will dig out my schematic when I get to it and double check. I am sure the fuel heats up that is why I tell customers to keep it above a quarter tank.

[wesman]

I switched your fuel pump driver to single speed vs. two speed in the tune. That setting is supposed to run on the high speed 12V relay all of the time. Another way of reaching the same end result.

Cool...I think the regulator is a problem for me as well. It's the next replacement part for me once I get back in town.

--wes

[charlie]

This makes sense, but why would you need to add an adjustable regulator if we already have a boost sensitive regulator. I haven't looked, but is there a mechanical regulator already on our trucks? If so , where?

Since the warbro pumps require 12V all the time I had an idea. After reading these posts I could easily add a pressure sensor and have one pump running all the time then turn the second pump on with a relay when you hit positive pressure on your boost. (Ford basically does this by cutting the voltage in half, I'm just suggestion only running one pump instead) That way during normal driving and idle conditions you don't have the additional energy and heat being added by unnecessary flow that just ends up returning to the tank by the second pump. One pump should be more than adequate for non-boost applications. Obviously this would require a check valve on the output of the non-full time pump to keep from back feeding.

Thats what I was thinking this morning... But I was thinking of activation the relay with voltage from the TPS. Then I was watching the fuel gage going to work, and noticed that the fuel gage was creeping up as I was pressing down the gas aggressively, but not flooring it.. And I don't know how I could duplicate this without varying the voltage on at least one of the pumps.

I guess I'll have to figure it out some how. Because I will need the 255's buy the time I put the other engine together. I'm just hoping I can delete the resistor and tune for the change.

Charlie

[Tex Arcana]

subscribing

[geezer99svt]

There is a new thread on this at nloc. Read this before you purchase.
http://www.nloc.net/vbforum/showthread.php?t=149964

Ron
Florida

[tiffo60]

ive been keeping up with the thread on NLOC and there getting a new batch of regulators together to ship out on the 30th that will be fully adjustable from 40 psi up to 60 so it should help out alot