skinny_9

superduty thanks for the help, the 392 will that be to much for stock equip, or it's not poss to go to big. extra will just be recycled.

can't stay after have one hour to get to 2nd job

Superduty

The 392 makes things simple because all you have to do is install the pump and a plain bypass. You don't need a regulator or a 2nd return line. It does move more fuel, but I don't see that being a problem.

04ctd

superDuty,

have you got a website (free one somewhere? free with your 'net service?) where you can consolidate all your knowledge, and maybe put up some diagrams?

nothing fancy, just the facts, kinda separated out by year.

i read alot of fuel posts, but like a lot of folks, it's difficult to keep it all straight.
i try to cut & paste everything for my year into a WORD doc for my truck.

Superduty

I replied to this with an answer, but it was censored.

mjgcamper

Superduty, I am a total greenhorn on these elect. fuel pumps. I can tell because of my complete confusion with more reading I do.

My 92 ctd has never had any problems like the fuel pressure problem I am reading about.

Now that I just bought an 02 (real cream puff) still under warrantee, I am very concerned, because I do not know what to do.

You seem to know your stuff and I want the Walbro, but how with a warrantee?

BTW, my greenhorn question is; is the bypass that you are talking about with the 392, is that a line to bypass the stock f/p? Shows how little I know!

Thanks much, Mike

Superduty

You have to get your own info on warranty and make your own decision. I can't guide you there.

The bypass is a piece of hose that goes between the inlet of the injection pump and the return line. Its purpose is to give the fuel a route to the return line to prevent massive pressure build up on the inlet side of the pump. Unlike the stock pumps, the Walbro pumps way more fuel than the injection pump can take and thus there needs to be a path for the excess to take.

Here is a comparison of a Walbro and the Holley pumps. I think the stock Dodge pumps (engine mounted and in tank) will be somewhere between the two Holley pumps.

The maximum pressure on these pumps is not where they were designed to run. The design pressures on the Holley Red and Blue pumps are 3 and 7 PSI respectively. The design pressure on the Walbro is 80 PSI.

Superduty

I am going to be checking out for a while. If you have any questions about Walbros, here is a list of people that have installed them. They hang out here and on other diesel boards generally using the same name as here.

Trik, Sea01Cummer, 04QC3500, Slim51015, Stump, bmallen, piperca and MaroonCumminsInOre

mjgcamper

Thanks very much Superduty, I understand. Great effort on your part. Sounds like theeeeeeeeeee setup. Maybe I can find some picks with a search on thebypass fuel line.

OPIE

So are there any other members here that are affiliated with Walbro? If so is this really an actual pressure to flow chart for that pump or was this made up by SuperDuty?

I do try to stay out of these things but feel there is no way this chart is correct.


Also it's been a couple months now any first hand experiences?

trik396

Had the Walbro on for about 1500miles now. I see 20psi most of the time. Not a hesitation or problem so far. Why do you think the chart is made up?
The Holley Blue and Red are advertized at 14psi and 7psi max pressure and the gallons per hour are in every Summit and Jegs catalog since I can remember. The Walbro charts are all over the net also. What's so hard to believe?

trik396

I think I may understand some problems here... Holley Blue and Red and others Holley makes are carb pumps. Sometime, somewhere, someone said, "Let's try this pump on our truck because the stock lift pump sucks"...
And it worked.... BUT it is working beyond its means and borderline at BEST.
But others followed suit. I have nothing to do with Walbro or Holley. I've installed, used and purchased many Holley pumps and carbs and parts, etc. I've only purchased one Walbro. In my opinion a carb pump doesn't belong on our trucks. It's not meant to pump the pressures we need at our injection pumps to keep them alive. Why is it hard to believe this? Because of blind loyalty maybe. And because "I read it on the net, so it must be true"... stuff like that. Any fuel injection pump will be far more capable than a carb pump in our respects.

OPIE

I could care less about electric pumps, really but I am having some math problems.

I have been testing several gear pumps lately. And it seems they all have one thing in common when pumping diesel. It takes 1/3 hp to make 100 psi at a flow rate of 60gph.

After seeing this chart I thought why not make one for my mechanical pumps too. Well lets just say of none of the mechanical gear driven pumps flow lines is as linear as the one posted. This led me to doing some math…

If it takes 1/3 hp to make 100 psi at 60gph what is that in amps?
746 watts = 1 hp So 1/3 or decimal .333 times 746 equals 248.41 watts
So it takes 248.41 watts to make 100 psi at 60 gph.(100 psi is a constant ref pressure.)
With the mechanical pumps I have tested.
248.41 watts divided by 60 gph is 4.14 This tells me that every gph takes 4.14 watts to make in for the sake of argument.
The linear line of the graph shows that at 100 psi the flow is around 46-47 gph.
So 46 gph times 4.14 would equal 190.44 watts .
Since Watts equals Volts times Amps.
190.44 Watts divided by 12 volts = 15.87 amps. And I remember something about the pump only having a average amp draw of 8 amps. If that is true 8 amps times 12 volts would equal 96 watts. If 96 is divided by 4.14 watts from above this gives me a ballpark of what I truly feel this pump is putting out at 100 psi with diesel. That number is 23 gph.
Which is half the volume that the graph shows.


I have a thing for real world testing.
I can set one of the bypass regulators that I make to 100 psi and I will use my truck battery to run the pump. Turn it on with the other side of the regulator is going into a fuel can for a minute. Take that result and multiply by 60 to get gph and viola the real world answer will be right in front of us. Right? So now I need somebody who isn't using theirs right now to loan it to me for this test.

trik396, Right now it doesn’t make a difference in your particular application. But if it isn't right it should still be corrected.

What do you think?

trik396

I think you are comparing apples to oranges.

When you are saying "it takes 1/3hp to make 100psi at 60gph", this is from a mechanical or belt driven pump? Correct?
If so, that pump uses 1/3hp off of the engine it's driven off of, ie, the Cummins. It has nothing to do with wattage or voltage or whatever.
Also, different pumps are more or less efficient than others of similar or different design.
Looking back at the graph, I don't think it is accurate. I'll find you the link for the correct graph.
As far as the amp draw of the Walbro, I don't know where you read 8amps was an average. The amp draw will increase with pressure. The lower the pressure, the higher the gph and very low amp draw. The higher the pressure, the lower the gph and amp draw up to 25amps I believe.
Why are you so interested in this anyway. Just wondering. You seem like someone who is knowledgable about our trucks and making power. And you don't seem like someone who'll ever use an efi pump. ???

trik396

http://www.autoperformanceengineering.com/

Go there and click on technical and you'll get flow graphs w/ amp draw

OPIE

trik396,

Thank you for the quick reply,

The above numbers are my findings when testing a few different positive displacement mechanical pumps. I have been using an electric motor coupled to each pump. And like I said, when I started charting an actual flow versus pressure chart while useing diesel. The flow wasn't linear like the one on the graph not even close. And that was even putting aside the hp thing required to run the pump. I went to the the site you listed and found that it listed the pumps by flow, is your pump in the graph listed there? The reason I ask is the biggest one there is only 255 liters per hour.

For 100 psi that chart claims that at 12 volts it takes 13.2 amps to make 22 gph.
If the the voltage is increased to 13.5 it takes 13.2 amps to make 32 gph.


The math is starting to work now and the 25 amp draw comment from you is why.

Originally I was only interested in making a graph. (I have learned from SD that people really like to reference them.) Now I am interested in finding out the truth. I am sure glad that the relay point with a fuse was brought out in the thread about who needs a FASS. The power draw numbers now make sense but I feel the flow vs pressure numbers are way wrong and when someone loans one to me I will post the real world numbers. Whether I turn out to be right or wrong it will be an interesting test.

Opie