Superduty

OK guys... Some of you know I started a ruckus about fuel pumps in 3rd gen engines.

The whole set of threads is outlined here:
https://www.dieseltruckresource.com/...ad.php?t=88136

I am starting the same discussion here as a means to get you guys discussing your fuel pump issues. I don't care one way or another how this turns out, I just think you might want to be aware of a few things before you buy your next fuel pump. I have no relation to FASS, Walbro, Bosch, Carter, etc. I don't drive a Dodge either.

There are other interesting lift pump discussions in 3rd gen. Search on my posts or "lift pump" and you'll see what I mean. I don't mean to be a trouble maker in this regard.

Do not PM me about this stuff. If you have a specific question for me, ask it in this post.

Have fun. Keep it clean.

So.. what is so great about the FASS fuel pumps ?

The fuel flow needed for 250 HP is

250 x 0.4 lbs/HPHr / 7 lbs/gal = 14 GPH for consumption.

Add on 30% excess flow for cooling and lubing the pump and you get 18.6 GPH.

For 325 HP. 325 HP x 0.4 lbs/HPHr /7 lbs/gal x 1.3 = 24 GPH

For 400 HP 400 x 0.45lbs/HPHR /7 lbs/gal x 1.3 = 33 GPH

For 500 HP 400 x 0.48 / 7 x 1.3 = 35.6 GPH

For 600 HP 600 x 0.5 /7 x 1.3 = 55.7 GPH

I increase the BSFC numbers as the power went higher because more fuel is wasted as hot exhaust as the power levels go up.

The pressure drop on a 10 foot 3/8" line at these flow rates is very low. A few to 5 PSI at most. There is no need for anyone to be replacing stock fuel lines with larger ones if a proper pump is chosen.

Picking up air in the fuel system is not the problem that people make it out to be.

My favorite lift pump is the Walbro GS392 pump.

It retails for about $140. It is a high quality, high pressure, high flow pump suitable for pumping either gas or diesel fuel. It is used as a rebranded OEM pump in some vehicles. I am not sure which.

It is cooled by the fuel that it pumps, unlike other pumps that are totally enclosed and run air cooled brushes, which wear out quickly. The Walbro is a gerotor pump. It will run at 60 or more PSI continuously in a fuel injection type application.

More info here http://www.autoperformanceengineerin.../ext_pump.html

Here is its delivery curve.




Before you go stating that a FASS pumps more fuel, you better get a flow curve for it. Fuel delivery rates depend on the back pressure. The FASS pumps deliver 95 and 150 GPM but at what pressure ?

What makes the FASS pump so good that you spend $600 on it ?

staarma

Where are you getting your brake specific fuel consumption numbers from? Are you using bore and stroke with RPM and output?

Superduty

I've calculated BSFC numbers in the past from the Cummins engine labels. They list fuel delivery per stroke in mm^3, RPM and HP. If you look in my posts you should see an example.

Incidentally, most of the Cummins engines have a BSFC around 0.390 at rated HP. It is pretty consistent from the 1st gens to the 3rd gens. Some of the first gens are up to 0.410. The 325/600s with the 3rd injection event are at 0.390. But we are off topic here. I guesstimated on the higher than stock HP BSFC numbers.

I think the 24V 230s have about the best BSFC at rated power, but that is going from memory.

staarma

Cool, was just wondering. I agree with the numbers and how they are achieved.

You have very good info in the other threads and I'm looking forward to some valid info from others in this thread as I'm curious as to why the FASS is becoming such a "household" name. I need to make a decision soon for fuel delivery as my pressure drops to 0 at WOT and it stutters bad at 2750 RPM under hard load with the boxes cranked up.

Superduty

I hope it is helpful to someone. That is why I wrote it.

"as my pressure drops to 0 at WOT and it stutters bad at 2750 RPM under hard load with the boxes cranked up"

That is bad, very bad !

staarma

Yeah I know, I'm currently driving like grandma.

crobtex

I didn't...............

BigBlue

I like my little holley. Puts out plenty of fuel for my measely 371hp.

Dodgezilla

My FASS works just fine so what's the big deal? I paid a lot less than $600.00 too. I did only get the pump though.. The FASS was a relatively easy install although I would have preferred a bolt on replacement for the stock LP. No offense but some people put way too much thought into simple things....

fredw

kenedey diesel sells lift pumps that when installed with the stock lift pump in the tank will maintain 15psi on wot with a aftermarket cp3 making 600hp, done with stock 3/8 line for a cost of 440 dollars

Superduty

And a Walbro will pump 65 GPH at 50 PSI and it sells for $140. Your 600 HP engine is sucking about 60 GPH max. The Walbro could probably be made to fit a Chev too.

What makes you guys pay $440 for the Kennedy pump over a Walbro ?

BTW: Do you guys have pressure curves for the Kennedy or Holley pumps ? I'd love to compare.

fredw

we could never keep the volume of fuel we needed with the fass in our trials, it maintained about 3psi on heavy fueling programs, and we think was the destrucion to a cp3 that went bad from the low volume we were told by the dealer..

we now found that the voulme has almost doubled and wot pressure will maintain above 6psi on a max

the same jk pumps on a cummins with the smaller fuel line and running with the lift pump in the tank will maintain 14psi on wot, they also flow threw the pump if it goes down, and has been proven over 25000hrs of operation..

i did hear of another guy playing with the fass regulator and such to maintain a 40psi on wot but never seen it with my own eyes

Superduty

The pump curves tell the story. Get us a curve for a FASS and we'll talk.

crobtex

What gives? If people are satisfied with their FASS, or Carter or whatever, why the big fuss about why the one you have is the best?

Superduty

No fuss. Just trying to share some info with people.

For some reason when people think lift pump they think FASS. Why ? I can't see that it does anything that the Walbro or the Bosch don't do.

I'm trying to get people to think. Go into the 2nd gen forums and you see post after post about lift pumps and VP44s. Maybe the Walbro will help the situation.