PaulDaisy

No, the idea was to use the huge overflow to filter the fuel all the time and get it cleaner and cleaner with time, more and better than the stock fuel filter does. That way my "efficiency" would be better, I could claim I re-use the extra GSL392 flow

I think so. I didn't measure it but the pressure my 392 is running at is about 40 psi (I can bump it to 50 or more if I find that the fuel pressure drops too much at WOT). 7-8 amps is what the pump flow / amperage curve shows for that pressure.

B-Valves, what are you going to use for the pressure sensor? Integrated and ruggedized stainless units with 5 V output and NPT threads retail for as much as $150.
I rigged up my PWM using a $1.50 8-bit microcontroller from Atmel. And, I used only about 1% of the capabilities of the darn thing the size of a match head. I could also probably run the entire truck off of it with the remaining timers, counters and unused program memory. I used a FET on the driving circuit; granted, I did not drive a pump with it, only a limiting valve. I didn't have a pressure transducer that would be economical enough to be practical. I used some Honeywells that are $35 apiece... too much. My application was gas pressure metering.
-P

PaulDaisy

Tony - didn't mean to ignore you. No I don't have a kit like that, but the more I read the pains of people here, the more I feel like making one for people, or at least speccing one for those who can turn a wrench.
-P

TonyB

Paul,
No worries...we all get busy!

Thanks for the reply.

Tony

OPIE

You ask,"Why the need to back it up?" I guess my reply is why make the statement if you nor anyone else can back it up?

So far nobody has chimed in on the following claims

"a regular Walbro 392 will support a 1000hp at 20psi delivery"
to dropping 200 hp
"a regular Walbro 392 will support a 800hp at 20psi delivery"

I seriously feel that if an additional 200 hp is dropped
"a regular Walbro 392 will support a 600hp at 20psi delivery"

The statement still wouldn't be valid. What is the difference between a racers and a street guy's fuel system?

So I am a competitive guy huh? lol

budsmission

08-13-2007, 08:13 PM
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bent valves bent valves is offline
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Location: New England
Posts: 142
I agree with HOHN that running a high volume pump is not optimum. The Fass and Airdog claim that fuel pumps cause air to be entrained in the fuel and their pumps separate the air out of the fuel. I believe this is because the pump is running at full speed and whips the fuel into a froth.

Last week I received a cheap PWM motor driver kit. By using a pressure sender and this kit it is possible to run the pump at the speed needed to maintain the pressure you set but not whip the fuel up. There will be no need for a bypass regulator.

Here is a link to the manufacturer of the kit. http://www.vellemanusa.com/us/enu/pr...iew/?id=350605
If you do a search for the K8004 DC to PWM kit you will find them for less than $20.

In the next week I hope to post my experience with this kit driving an Aeromotive gerotor pump, similar to the Walbro pumps. It looks like this kit will power an electronic pressure sender and by using the pots on the PC board, makes the pressure adjustable. Just give me a few days.
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Dave
Old 08-15-2007, 01:54 PM
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Posts: 142
Here is an update on the DC to Pulse Width Modulator kit, K8004.

The intent of using this kit is to control the lift pump speed to adjust the fuel pressure to a set point you choose. To do this a pressure sender is used to modify the duty-cycle of the voltage to the pump. The kit I chose has all the things needed to do this and I had assumed it could be modified to lower the duty-cycle with a rising pressure. This negative feedback is needed to keep the pump from running at full speed all the time. The IC chip has both positive and negative inputs, which I assumed could be used for this application. Unfortunately this is not the case. After building the kit I found the SG3525 IC chip cannot be run in this way.

I got looking around for an easy answer and came across another chip, SG3537. This is a direct replacement for the SG3525 but has the correct sense to lower the duty-cycle with an increasing fuel pressure. This will be the answer for an easy PWM circuit to control the lift pump. The only problem I have now is trying to buy a small quantity of these chips. Most places only want to sell them in 1000s. But I will not give up easily; just add a few more weeks to my quest for a cheap and easy PWM circuit.
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Dave

Dave, Your PWM idea makes great sense to me. I don't have tape on my glasses--I am a retired pastor and missionary--but I do know which end of a soldering iron to pick up--just not how electronics work. I have a lot of questions:
Could the sensor be hooked up to the outlet port on the FF?
What is a "snubber?"
Have you found a way to get that other chip yet?

You mentioned it works with Aeromotive and Walbro type pumps that have an internal type spill back valve -- I have a Holley black rated at 140 gph with preset 15 psi output. My pressure shouldn't need a bypass regulator but my interest in the PWM set up would be to make it easy on my pump so I wouldn't have to change it often.

Thanks, Bud

bronco68

I have been running a Walbro pump set up for 2 years put together by Turbo Auto Diesel in Phoenix, AZ.
This pump has been incredible. It has both the Walbro 392 and a controller that senses voltage through the TPS (APPS) and adjusts accordingly.
I maintain 15 PSI at idle and when i give it more fuel it goes to 20 PSI at WOT. To have a set up that actually gives you more fuel as you need it is in my mind the only way to go. This is accomplished by regulating the voltage to the pump, thereby, only using a small amount of the pumps capacity.

budsmission

Bronco 68,
Thanks for the info. Sounds like a good idea, especially the part about using voltage to control output. How pricey was the setup? Also, do they put together a kit, as I live a long way from Phoenix.
Thanks, Bud

AlpineRAM

Do you have company e-mail or website info about them? I would be interested in some sort of regulator, I have a walbro GSL392 already.

THX

AlpineRAM