READ THIS about mileage and air in fuel

[SoCalDMAX]

All,
I was reading the 40+ pages discussing the PSD cackle problem when one post pointed to this site.

For those who are disappointed with their mileage and/or power, this information might help explain a phenomenon common to all diesels. Perhaps there is more air in our fuel than we realize.

http://preporator.com/All_Diesels.htm

Short version: Diesel fuel has air entrained in it to begin with. Slosh it, pull a vacuum on it or heat it up, and more vapor is created than we realize. All current diesel fuel systems allow fuel to slosh in the tank, return heated fuel to the tank and suck the fuel long distances from the tank.

This all adds up to more air/vapor entrained, which causes power losses and up to 8% decrease in mileage. Test cells are constructed with the tank above pump level, giving positive pressure, not to mention they're larger than a vehicle tank and don't get sloshed over the road.

These guys are selling a pump/filter assy that removes entrained air, increasing power, mileage and increasing pump and injector life.

They state liquid doesn't compress (true) but vapor does (true) and all injectors are hydraulic in operation (true) and injector timing can be severely retarded due to compression of the vapor before the liquid gets squirted, causing loss of power and poor economy (sounds true.)

Also, I've NEVER understood why we don't have an in-tank pump like gassers, with an automatic or plug-in heater to boot.

Can anybody add more to this, explain if it's snake oil or true?

Regards, Steve

[wangotango]

The theory seems quite sound. Looks like it does indeed make a difference. Not sure how much it costs but could it be worth the amount of increased mileage/power. If it is a reasonable price it seems like a good idea for the long-term.

Upon further review: looks like a fuel/air return line would need to be installed to fuel tank, I'm not sure where it could be mounted-looks like it's a pretty big package.

Interesting stuff.
Good research.

w/t

[NutNbutGMC]

Quote from the web site:
" For more information, or to order, you can contact us toll free at 1-866-POWERHP (866-769-3747)."
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The information may or may not be 100% valid. However, it seems like a marketing technique. Thanks for the info. smile.gif smile.gif

[IndigoDually]

Isn't there a heater bulit into the top of the fuel filter? :confused:

[SoCalDMAX]

W/T,

Sure seems like the hydraulic principles they quote seem to be correct.

NutNbutGMC,

You're absolutely right, they're selling something. I'm just curious how much it costs, how big of a problem this really is on a Dmax and do they give a money back guarantee?

Indigo,

You're right, but based on the theory that a fluid under vacuum boils (or just releases vapor) at a lower temp., then heating it at that particular spot in the system only adds to the vapor problem.


I'd like to get 20mpg at 75mph, but doubt it. I'm just thinking that this could help explain the wild swings we see in mileage from one tank to another and from one Dmax to another. Perhaps those with poor fuel mileage have a miniscule leak that's aerating their fuel and causing poor power (imperceptible) and poor mileage. Perhaps those reporting 19mpg at 70mph have perfect seals, and the rest of us are leaking to some degree.

One of the PSD owners was looking at the fuel in his return line, and it looked like foam. He found that an o-ring in a fuel line was allowing massive air into his fuel system. He used a regular rubber hose and clamp, and eliminated that problem. IIRC, we have the exact same type o-ringed fittings in our fuel systems, and they're designed more for a pressurized system, not a vacuum system.

Just wondering about it, the wide variances in mileage between trucks has me bugged. I'm calling them tomorrow for more info.

Regards, Steve

[jgrimm]

With regards to the in tank fuel pump:

I interviewed a mechanical engineer about 2 years ago. I questioned him about his previous employment at Ford. He work in fuel systems design. (This before I owned a diesel BTW) Since I had just replaced the fuelpump on my wife's blazer, and was surprised to see very little insulation/shielding around the pump, I asked him why they don't explode. He told me that gasoline is so volatile that no matter what the temperature/tank level, so long as the tank is not vented improperly, the gasoline vapors always displace the air. So you can actually have a spark inside the tank with no ignition.

He then went on to tell me that diesel tanks are a different story. At a certain tank level/temperature (I think it was around 1/3 tank at ~75deg) diesel fuel is not volatile enough to displace all of the oxygen. And because of their studies, Ford decided to never install in-tank pumps on diesel systems.

I thought it was interesting and made sense.

John

[SoMnDMAX]

A good friend of mine used one of these on his '88 and '94 Freightliners with a 3406B and 3406C Caterpillar engines, and in his '98 Peterbilt with a C-16 Caterpillar engine, and gained between 1/2 and 1 MPG on the trucks. No power showed up on the dyno, but the gains came at the pumps. Before you say that 1/2 or 1 MPG isn't much, it's a bunch when you're running a truck that gets between 4 and 6 MPG!!!

They work, but the question I have to ask, is: Is it really worth it for us? I can pull 20+ out on the open road, 16+ in town, and 14 pulling trailer. I'm happy, and would rather not invest another $1000 in my truck. Unless of course, it gains me another 100 HP or so..... :D

[maxtotow]

my first post here!
In line with this fuel question.
Can someone explain the function and use of the fuel cooler in front of the fuel tank?

[IndigoDually]

Maxtotow, The fuel in used to cool the injection system electronics. They run at a higher voltage 96 (I believe) versus the truck's 12 volts. When this voltage is stepped up the transformer creates a lot of heat and the fuel is used to cool the computer and transformer. This is why it is really not a good idea to run the level of fuel in the tank too low especially if the ambient air temps. are high. The fuel temp will get too high and not provide enough cooling and might cause slight performance issues.

Does anyone know if the fuel heater is thermostatically controlled (I would think so) or is it always on?

Since we are on the subject of fuel voodoo, I knew of a guy who had special magnets that wrapped around the fuel lines near the injectors. The magnets yielded him a pretty good rise in mpg. and I wondered if anyone else has seen this before? Magnets do strange things, I don't use my salt based water softener anymore, I switched to an electronic one and it works almost as good as the salt.

[Vivayo]

First post here. I've been lurking for a few months, and have come to the conclusion that my next p/u will be a 2500HD. I've also lurked on the "other" sites and feel that, all things considered, the GMC/Chevy product is the best on the market. I "want" a D/A but, in reality, the 6.0 is probably all I "need" to pull my 25' travel trailer (7,200# GVWR). The wife has given me the okay, but then she doesn't have to pay the bills.
The passing comment about the magnet on the fuel line reminded me that, just today, I received an email sale announcement from Harbor Freight and they're offering this product on sale (down from $12.99). It sure sounds too good to be true - 11+% increase in MPG - but maybe someone wants to be the test case???

"Save Fuel and Money"
"Simply strap to your fuel line to save gas and increase engine efficiency. Fuel Master's magnetic field breaks up clusters of hydrocarbon for more complete burning. Prevents build-up of dirt in engine injectors. Gives you 11.6% average highway fuel savings as tested by an EPA accepted laboratory.
Use it on cars, trucks and small engines.
ITEM 36098-3VGA $9.99"
I really enjoy all the posts on here and have gained a tremendous amount of info that will be useful, regardless of which version (of the 2500HD) I wind up getting. My personal preference for the 2003 styling is GMC...but I want to see them both in person before deciding which to buy.

Charlie
No affiliation w/HF other than I send them $$ occasionally and they send me merchandise - some of it is okay, some of it is junk.

[SoCalDMAX]

Hi Guys,

Just got off the phone with Brad, the mfr of the Preporator. The unit is $925 and the fuel line kit is another $50. It was primarily designed for owner/operators of big rigs, but will fit/work on pickup trucks. It's a little tall, at 21" (long filter) or 16" (short filter.)

He has it installed on his personal Cummins as well as a number of other Cummins powered trucks. It's also been installed on a few PSDs. Everyone's reported 8-12% fuel economy increases, lower noise and 25-30hp power increases, but there's no written guarantee.

They're looking for someone in the St Louis, MO area to let them install it on a Dmax. if interested, give them a call @ (866) 769-3747.

Regards, Steve

[SoCalDMAX]

Oh yeah,

Before I forget, a big WELCOME TO THE FORUM to maxtotow and Vivayo! Glad to have you here, great place to meet other Dmax owners and get your questions answered, as you guys have already figured out. ;)

Regards, Steve

[BlackMax]

This thread makes me wonder about a point I brought up in another post. When I change my fuel filter it is only about half full of fuel. I have been wondering how all of that air got in the filter if this is a closed system. It makes me wonder if I have an air leak. The truck runs fine but the milage is never over about 17 1/2.

[RWSDIESEL]

The fuel kooler is also needed because the Diesel fuel that is returned to the fuel tank comes from the inside of the Cylinder head from the injectors, and even passes through a small portion of the cylinder head, which at this point picks up alot of heat, without this kooler the fuel in the tank could aproach engine operating temperatures.

[hoot]

The fuel is also heated by extreme pressure in the fuel rails before some of it returns to the tank.

[RWSDIESEL]

hoot,
oh yes, and also heated in the fuel pump which is located inside the front of the engine, another hot place. Lots of heating everywhere.

[SGJ]

IndigoDually ,
I was recently at a machinery show where I saw the magnets you mentioned . The salesman gave me the whole sales pitch including showing me letters from commercial truckers claiming increased fuel mileage .He told me these magnets are different than any other magnet and were developed in Germany . When he was done his pitch I asked him how many people think these are a gimmick and he replied almost everyone he talks to . I don't know what to think of these as we all hear so many stories of increased milege if we put updates on .
The web site is www.cktdirect.com ,the dealer is Clair McDougall @ 1-800-313-5903 . He recommended two of these magnets for the Duramax @ $89.95 Canadian each . Not the most expensive mod but does it work . We need someone with a daily route to try them who knows exactly what their fuel mileage has been running . If we installed every fuel mileage trick for sale and they all worked as claimed we would get over 50 MPG . We could be so lucky !!!! :confused:

[moisheh]

SGJ: Please do not be gullible and fall for that nonsense. Why would you think it would work? If half of these magnet claims worked every vehicle in N.A. would be equipped with one. Doo you know that you can alos put these magnets on your wrist to cure arthritis. If placed on your water line in the house all your water will be softened. Next thing they will suggest that if placed on the appropriate part of your body Viagra will not be needed!

[IndigoDually]

Well I can say from experience that magnets do work. I have used cheap bracelets that don't work but I currently wear a $100 bracelet that does work. I can also tell when their effectiveness is gone (don't know how) and the bracelet needs to be replaced, when I put on a new one everything is better with my lower back. And my water is softer with the electronic magnet being used. :D

[SGJ]

Moisheh,
Nowhere in my post do I mention anything about being gullible or falling for this . I was simply passing on information on a question being asked . Read the last line about all the add on products and 50 MPG , do I sound serious ?
As for whether this can work , the technology has already been used before , in the 1940's the U.S. Air Force used a device on their Mustang aircraft to increase range and overcome poor fuel . It was so succesful it was then used by the Royal Air Force on Spitfire's and Hurricane aircraft . This however does not mean that it works on these engines . Just keeping an open mind , pessimistic , but open .

[SoCalDMAX]

Brought this back from the grave. with recent talk about air in fuel filters, might spark some more ideas.

Regards, Steve

[LanduytG]

George Morrison in one of the fuel filter threads said their were magnets out that do all they say but the price was way more than $100. George's company did research on the magnets for a large trucking company and found that they really do work. I don't beleive everything I see or hear when it comes to a sales pitch, but I feel confident that George would not leads us down the wrong path.

Greg

[ 04-20-2003: Message edited by: LanduytG ]</p>

[Burner]

What are they, rare Earth magnets that cost 20 bucks a gram?


Burner------&gt; :D

[CanadaKev]

Steve,
Thanks for reviving this thread. I hadn't seen it before since it was before my time on the DP. Very interesting.
If(in theory)we have more air in our fuel when our tanks get low, than when they are full, and air in fuel decreases MPG; then we should get a better MPG on the top half of our fuel tank than on the bottom half. Right???
Just wondered if anyone has done any research on this theory?

Kev

[GMC-2002-Dmax]

To All,

I just got back from a trip to Outer Banks, NC and from CT to OBX it was a hair under 600 miles.

I drove 75-80 mph with a few runs pegged at 97 playing with a Vette on the Jersey Tpk. and after checking the fuel mileage I averaged 19-19.5 mpg at those speeds with the AC on, I did have a tonneau cover.

My fuel improver was compliments of EDGE - HOT Juice in Level 4. I was pretty empty with just myself, 3 kids and luggage so approximately 1000 lbs of people and gear.

I never saw EGTS over 450 while cruising and even into it I saw 700 only once pulling a hill.
People in cars were a little shocked when I would go by them, the JUICE rocks!!!! :D

I don't do anything special and always get good mileage. I did have the stock 245's on and not the 285's. Next trip will be with the 285's so I can compare mileage with them.

GMC ;)

[ 04-21-2003: Message edited by: GMC-2002-Dmax ]</p>

[SoCalDMAX]

Kev,

I don't know how much the fuel level would affect the amount of vacuum, probably not much, but I certainly notice the 1st half of the tank lasts a LOT longer than the 2nd half!

Regards, Steve ;)

[a64pilot]

Burner,
These magnets are made of "unobtaniun" a rare and magical element.
To all,
The reason you go farther on the first half of the tank has to do with the way the gauge is calibrated, the actual fuel mileage does not change.

[moisheh]

Magnets are a hoax. As for softening your water . Ther are lots of web sites that explain the hoax. I would love to be able to spend a few bucks and improve my mileage. If they work so great why dont they install them as OEM. The big 3 are having trouble meeting EPA requirements Maybe a few Mil spent on magnets would save them a lot of trouble. Ya right!