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what controls the voltage?
It is an inferred table and it cant quite control the voltage like you see it listed in the table, it kinda just controls the "rough" voltage given to the pumps via the dropping resistor and high/low relay.

So your not going to get 8 volts on the dot you will get a blend from the lowest voltage on the table to the highest. You may see 8v for a millisecond or so while the voltage is on its way to full system voltage.

Also keep in mind when the table shows 12v that will actually be full system voltage so if your running 13.8v with the vehicle running thats what your going to get.

JJ
 

· 10 second street truck
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I have print,
Both pumps get 12 volts to run not more or less volts, both pumps have simple relays to turn them on and off . Secondary is a GROUND path trigger. Fore needs to see 6.5 volts to trigger it's relay.
You would have to re wire the secondary rely to not ground but send B+ to Fore, thats why its bypassed. It can be rewired to B+. But my tuner doesnt know if he can change the input value in the PCM to 8 PSI on/off
I get it just send 12 volt to both Fore inputs with key on and they run. I'm trying to keep factory control. I don't want both pumps to run on cruise

Just to re-address this for anyone reading this post.

The relays do not turn the pumps individually on and off.

The pumps run in parallel. They are both always on. In stock form, there is a high-speed and low-speed circuit. Based on fuel demand the pcm will trigger either the hi or low relay. When the high is triggered the pumps get full voltage and run full tilt. When the pcm commands low speed the voltage to the pumps is sent through a 1.3 ohm resistor that drops the voltage to approximately 7.5 volts. Give or take.
 

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Discussion Starter · #25 ·
OK, the resistor and the secondary low relay are out of the picture with the Fore stuff. I hear what you are saying about the quality of the Fore stuff. I'm down to running both pumps all the time with the B+ from the cutout relay
Or using a Hobbs 8PSI to trigger Fore 2 from the B+ at the cutoff relay, either way is straight forward.
Sorry I make it so painful
 

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Discussion Starter · #28 ·
After talking to some other gear heads, I've decided to go with the Hobb's switch to trigger the secondary (Fore) pump.
Yes the factory pumps get B+ from the same fuse on both pumps and yes when the seconday pump turns on thur its relay it drops the voltage slighty to slow the flow down on both pumps that is far from the next GEN F150 with a pump controller that rots out on the frame rail and causes all kinds of problems.
In the end why load up the alternator and run the secondary pump on cruise for no reason?
I'm not going to.
 

· 10 second street truck
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13,059 Posts
After talking to some other gear heads, I've decided to go with the Hobb's switch to trigger the secondary (Fore) pump.
Yes the factory pumps get B+ from the same fuse on both pumps and yes when the seconday pump turns on thur its relay it drops the voltage slighty to slow the flow down on both pumps that is far from the next GEN F150 with a pump controller that rots out on the frame rail and causes all kinds of problems.
In the end why load up the alternator and run the secondary pump on cruise for no reason?
I'm not going to.
It doesn't turn on a secondary pump in the factory wiring. They're both always on. Jesus.
The pumps are both on at either 7.5 volts or 12.

1000s of trucks running both pumps at 12v all the time. Zero issues. But you're going to be complicated and different simply for the sake of being different.
 

· 10 second street truck
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13,059 Posts
Little data for anyone curious.

Stock 190 lph pumps x2. At 13.5v @ 40 psi(basically cruise) they're pulling 6.8 amps each. Total 13.6 amps

Dw300's which are 340 lph e85 pumps. At 13.5v @ 40 psi they're pulling 7.6 amps each for 15.2 amps.

The walbro 450's that fore sells in their hat @ 13.5v pull 14.1 amps each at 40 psi. 28.2 amps


This is one reason I always ask people if they really need 450s...

That said the stock alternator is 130 amps.

So in stock trim the pumps draw 10.46% of the alternator capacity.

The dw300s draw 12%. I'll give up 1.54% to not complicate a fuel system that works.

The 450s draw 21.69% fwiw.

On e85 the required flow for 750whp is something like 550 lph. So the dual 340s is plenty.
 

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After talking to some other gear heads, I've decided to go with the Hobb's switch to trigger the secondary (Fore) pump.
Yes the factory pumps get B+ from the same fuse on both pumps and yes when the seconday pump turns on thur its relay it drops the voltage slighty to slow the flow down on both pumps that is far from the next GEN F150 with a pump controller that rots out on the frame rail and causes all kinds of problems.
In the end why load up the alternator and run the secondary pump on cruise for no reason?
I'm not going to.



No offense but here is what is going to happen. Your trying to reinvent the wheel. You have just enough knowledge and ability to work on these vehicles but those things are also going to give you fits. You are over thinking, talking to the wrong people and also thinking that you are going to do this better than anyone else has done before you. The problem is your not the first to do that. Many have been there and done that and wound up getting frustrated, spending way more money on parts and way too much time that is honestly not needed. The three main people in this discussion are giving you solid information that is proven to work and your just tossing it aside because you spoke to "some other gear heads". I dont think you understand fully how unique these vehicles are and how deeply knowledgable the people who are giving you advice are.

I wish you luck and all the best and please dont take offense to what I'm saying but its true.

Never mind.
Agreed
It doesn't turn on a secondary pump in the factory wiring. They're both always on. Jesus.
The pumps are both on at either 7.5 volts or 12.

1000s of trucks running both pumps at 12v all the time. Zero issues. But you're going to be complicated and different simply for the sake of being different.


Little data for anyone curious.

Stock 190 lph pumps x2. At 13.5v @ 40 psi(basically cruise) they're pulling 6.8 amps each. Total 13.6 amps

Dw300's which are 340 lph e85 pumps. At 13.5v @ 40 psi they're pulling 7.6 amps each for 15.2 amps.

The walbro 450's that fore sells in their hat @ 13.5v pull 14.1 amps each at 40 psi. 28.2 amps


This is one reason I always ask people if they really need 450s...

That said the stock alternator is 130 amps.

So in stock trim the pumps draw 10.46% of the alternator capacity.

The dw300s draw 12%. I'll give up 1.54% to not complicate a fuel system that works.

The 450s draw 21.69% fwiw.

On e85 the required flow for 750whp is something like 550 lph. So the dual 340s is plenty.
Good information, I hope the OP takes it to heart and yes I agree, anything over 340's should get an entire fuel system anyway with proper controller.

[email protected]
 

· 10 second street truck
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13,059 Posts
OK , my E-force charged 675hp 2010 Vette works with a hobbs switch. I'll let you know how the Hobbs works on the 02 5.4,
It's not the use of a hobbs switch that is the issue. Guys with 3 pumps run 2, and a third on th hobbs all th time.

But you're taking a functional, OEM style setup, and complicating it.

When the guys run 3 pumps they run 2 in OEM configuration. 2 pumps, always on. The third tends to kick on around 8 psi.
 

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109 Posts
Discussion Starter · #36 ·
yes not apples to apples. OK I asked for your help, you guys gave it, KISS. I'm going to run both Fore 1&2 key on from the factory pump connector. I have most of the wiring routed/installed
 
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