[MNorby]

Possible the two walbros don't feed enough or you don't have a bleed hole walbro in the system so it is trying to suck them closed by the pump or something like that?

 

[moparmaniaccuda]

In that link, they state that a single Walbro pickup can provide up to 40 GPH flow rate. Does anyone know if that's actually correct?

Anyone?

It seems to me that if each one of these is rated for 40 GPH, two of these should provide enough flow for a ~66 GPH (255 ltr/hr) fuel pump.

 

[inphobic]

The Pick-ups are pieces of molded plastic. It is possible that there is flashing inside the line or that it is just not working right.
Glad you found your issue with out the $360 expense. Now though the question is do you try a different walbro pick-up or a different approach?

Jake

 

[Fl-Krawler]

My understanding of cavitation is that the air bubbles do not remain in the system. In fact, I'm not even sure the void created during a singular cavitation incident is really "air." I think people just refer to it as air because, well, what else would you call it? But I'm pretty sure that if you were small enough to get trapped inside a cavitation void you would suffocate. That or die of vacuum exposure.

Anyway, cavitation is when the void is created and nearly instantly implodes upon itself. causing a microscopic water-jet-like effect on the surface which is was created on. I don't think the "air" stays in the system and travels on.

Plus, he's saying the pump sounds much better, which says to me that it is not cavitating, or at least not as bad as before.

My bet is that air is coming from somewhere upstream of the pump, loose fitting or something.

Right now with the one pickup most of his intake is now probably coming in through that loose tube where the other pickup was. (Path of least resistance.) But still awesome that removing the pickup seems to have helped. I know that there could be other explanation for the improvement, but at least my crazy theory is not totally debunked yet.

I ran out of time to get mine running. I'm going back to the shop tomorrow and should easily be able to do it then.

Almost all liquids have some sort of microscopic bubbles in them, but as hydrophobic solutions, those bubbles are usually stabilized and don't cause any issues. Changes in pressure cause those microscopic bubbles to form together and form larger bubbles. The change in pressure could be from the walbro pickups, an obstruction in the line, the pump itself, the regulator or even one of the bends in the line.

I might be wrong, but aren't most gasolines heavily oxygenated these days to help with emissions? At this point I don't really think it matters what they are, other than that they are part of the problem:flipoff2:

Anyone?

It seems to me that if each one of these is rated for 40 GPH, two of these should provide enough flow for a ~66 GPH (255 ltr/hr) fuel pump.

I have a few fuel cells that I have built with only two walbro's and the walbro 255 pump in service and they have all been issue free except for two issues:

1. When the fuel level gets low enough to start uncovering one of the pickups, the pump gets really loud, and stays that way for a good 30min or more sometimes before gradually returning to its normal sound

2. When the inside of the cell has trash or water in it. I have found that both sediment and water, both in small amounts will cause a walbro to suck shut, to the point that they will cause the engine to sputter and die.

When I build fuel cells for other people I use walbro pickups most of the time, but I will put as many in the fuel cell as the customer is willing to buy. Its also because of threads like this one and others, as well as the above issues that I now will only put a minimum of 3 walbro's in any cell that I do.

My new buggy has the same drivetrain as the OP and I felt comfortable with using walbro's in it, mind you 6 of them in a very small fuel cell. Since then, a few things have changed direction in my build and with the addition of a supercharger I knew I would have fuel delivery issues. Because of that I went with an Aeromotive stealth A1000 in tank pump. They supply their own pickup screen with it, and it will feed up to 1400hp. I will just have to build some in tank baffling Aeromotive*|*18668 - Universal A1000 Stealth Pump Assembly

 

[Dookey]

Now though the question is do you try a different walbro pick-up or a different approach?

Jake

I'm thinking I will try a different approach this evening. Tired of dealing with problems.

 

[inphobic]

LOL! You are way closer to being done than I am with mine..

 

[patooyee]

Anyone?

It seems to me that if each one of these is rated for 40 GPH, two of these should provide enough flow for a ~66 GPH (255 ltr/hr) fuel pump.

I recently cut one of my bad E8248's apart to see what was going on inside. If you think the 10mm fitting that the GL392 sucks gas in through is small, you should see the internal passage that the E8248 has to get its supply through! It's the size of a broken pencil lead tip. And the E8248 has a massive -8 inlet fitting in front of it, why I don't know. I have another bad E8248 and a bad Bosch 044 here. I wish I had a GL392 but I doubt it is that much different internally. I'm going to cut them open and take pics and post them soon. You will see what I am talking about.

My point is that I don't believe the pumps were designed to suck through a twisted passageway of kinked tubing, 90* fittings, and fancy pickups which themselves are a 90* fitting blocked by a plunger. They are designed to basically have their inlet submerged directly in a massive supply of clean, cool fuel. They use sock-type pre filters which are minuscule in terms of restriction and that is IT. They are designed to have a constant, plentiful, almost completely unrestricted supply of cool, clean fuel.

And then we attach a bunch of restrictive shit to it, blow our radiator fans at the fuel cell, and wonder why they don't last. We all should know by now how inefficient pumps are at sucking at the intake.

Think about the power steering companies and their recommendations for remote reservoir supply lines. They absolutely fear 90* fittings, recommend a 4" or so hose with the res directly over the pump to reduce restrictions. Basically, in an ideal world, they would all have a straight steel tube going from res. to pump. Now imagine the conniption one of them would have if you called them up complaining about your ps pump whining after you told them you are trying to draw your supply though 3-4 90* fittings, some kinked tubing, uphill, through a magical plunger, blah blah blah. I know its not apples to apples, but damn, do ALL hydraulic rules of thumb go out the window just because its gas?

Again, just my personal crazy theory.

 

[Tazer15]

Andy look at it in a positive way you have created a great tech thread for all of us!:flipoff2:

 

[smewhtguy]

Here is the straight shot as mine is set up, I did cut down the input hose to about 4" from the tank to prefilter. I agree with pat as there needs to be as little restriction in and out of the pump as possible.

 

[Dookey]

Andy look at it in a positive way you have created a great tech thread for all of us!:flipoff2:

I accept donations. :flipoff2:

 

[Mutt]

L&M Engines

Fuel Line Sizing


Many people base fuel line sizing based on common misconceptions and customs and as such a fair amount of fuel installations may be fine for a race only application they are unsuited for street applications due to the street duty cycle being on average 20%-30% with idle, city cruise of 15%-20% of the engine power and if the fuel system has reserve these duty cycles would be 5%-10% of the fuel system capacity.

Fuel pressure supply lines are usually adequate for maximum performance, with a preference of 125%-150% fuel line delivery of 100% power to ensure adequate fuel in the event of an unforeseen problem with fuel delivery, i.e. pump speed/voltage/dirt. Fuel pressure lines should be sized to expected capacity and fluid velocity below 4 fps to reduce the Reynolds Number which signifies excess turbulence hence reduced performance.

With such low volume use of the fuel system capacity return fuel lines area usually inadequately sized. The purpose of the return line is for the unused fuel delivered to the engine to be bypassed back to the tank as all constant volume pumps cannot be dead headed. When this fuel is bypassed it experiences a pressure drop and any air dissolved in the fuel or entrained in the fuel boils out forming air bubbles as well as any fuel components vaporizing during this pressure drop. Ideally we want this activity to occur in the fuel line and not in the tank. When the pressure drop in the line is not sufficiently close to ambient the gasses do not condense back into the fuel and the air does not form complete bubbles in the line to escape the fuel in the tank. What does occur with an insufficiently sized return line is that when the bypassed fuel returns to the tank there has not been a sufficient pressure drop in the line and the remaining pressure is discharged in the tank and with it air and gasses discharging forming foam. Return line velocity should preferably be less than pressure line fluid velocity to accomplish the reduction of foam and fuel rail pressure rise.

Fuel line bypasses are commonly called a regulator which is incorrect. A regulator controls pressure on the outlet of the regulator, regardless of the input pressure to the regulator. A fuel bypass function is to bleed off a preset pressure to the outlet; the outlet pressure should be atmospheric and is determined by any restriction downstream. The bypass outlet pressure is ideally ambient atmospheric although return line sizing if too small will increase outlet pressure and added rising fuel pressure line/rail pressures. Another problem with fuel bypasses is the under sizing of the bypass orifice resulting in low flow causing low fuel consumption pressures higher than high fuel consumption pressures causing erratic fuel rail pressures. A larger bypass would be required or a series of bypasses to bypass the total fuel not used at low fuel consumption conditions.

Return line example - If the engine requires 600 lb/hr of fuel at maximum power and is used in low speed/power applications then the return line and bypass needs to return 90% of the fuel with ideally no pressure loss. That would mean a return line sizing equal or larger than the pressure line.

The fuel line sizing calculator is used to determine pressure losses and velocities of fuel by incorporating viscosity, Reynolds Number, D’Arcy-Weisbach Friction Coefficient, Colebrook Equation for friction for the final output of pressure loss in psi. Head pressure is also used and requires the input of the fuel rail elevation above the fuel pump to establish pump pressure to overcome gravity. This calculation can also be used to establish suction head which is the distance from the fuel level to the pump inlet and it can be used for pump performance.

The output of the fuel line sizing calculator is that with the known pressure losses one can consult fuel pump performance charts to properly design the fuel system to engine rated power.

 

[Dookey]

L&M Engines

Layman's terms? What I read means the return line needs to be larger than the feed line so there is less viscosity in the line?

 

[Mutt]

Layman's terms? What I read means the return line needs to be larger than the feed line so there is less viscosity in the line?

Basically if you don't want bubbles your returns need to be bigger. I don't see the bubbles being any problem for you, just found information explaining what is causing the bubbles :smokin:

 

[Dookey]

Basically if you don't want bubbles your returns need to be bigger. I don't see the bubbles being any problem for you, just found information explaining what is causing the bubbles :smokin:

I'm having a difficult time believing the bubbles are a problem as well. I could see it being a problem if the return port was right next to the pick up but since my pick up tubes are at the ends of the tank I don't see the bubbles causing a fuss.

Would be interesting to swap out the return tube with a -8 and see if it went away.

 

[TBItoy]

I can't believe anyone uses inline pumps, snow mobile pickups, and any other of that silly shit.

I'd quit fucking around and put the pump in the tank with a sock on it like it's supposed to be.

It'll be quite, cool, and have plenty of fuel with a baffle box around it.

 

[Dookey]

I can't believe anyone uses inline pumps, snow mobile pickups, and any other of that silly shit.

I'd quit fucking around and put the pump in the tank with a sock on it like it's supposed to be.

It'll be quite, cool, and have plenty of fuel with a baffle box around it.

This is the thread to put a list together with your superior knowledge. Part numbers are great. Specific sock part number would be great.

This is not the thread to tell everyone else what not to do. Vague posts can GTFO. :flipoff2:

 

[Fl-Krawler]

This is the thread to put a list together with your superior knowledge. Part numbers are great. Specific sock part number would be great.

This is not the thread to tell everyone else what not to do. Vague posts can GTFO. :flipoff2:

Everything you need:flipoff2:
EZ-EFI® 600 HP Fuel Pump Kit Fuelairspark.com

That above kit is what I was going to use, but with walbro pickups, before I decided to add a supercharger to my build

 

[TBItoy]

This is the thread to put a list together with your superior knowledge. Part numbers are great. Specific sock part number would be great.

This is not the thread to tell everyone else what not to do. Vague posts can GTFO. :flipoff2:

It's been covered before, but I'll go copy posts from other threads.

here's a start, that exact walbro pump is also available as an "in tank" pump that comes with a sock instead of a barb fitting

 

[Tazer15]

Ive seen so many threads with inline fuel pump issues its had me worried for awhile.My prob is I bought a fuel cell thats 8" tall and I broke my stock fuel pump nipple off dropping it out of the jeep.Gunna cost me a boat load to change direction now!So id like to see this figured out not to say Ill have the same issue but the way my luck goes I will.:shaking:

 

[Dookey]

It's been covered before, but I'll go copy posts from other threads.

here's a start, that exact walbro pump is also available as an "in tank" pump that comes with a sock instead of a barb fitting

Now you get it. Thank you for helping.