Any EFI experts out there? Fuel problem...

[mtm_seven]

Hey Gang,

I'm trying to chase my last EFI problem and need some help.

I have a bastardized setup but I'll try to hash it out.

Vortec 350
700r4
Edelbrock Pro Flo MPI (4 barrel manifold)
FAST XFI retrofit upgrade (to make the edelbrock ODB II self learning)
Stock tank (clean)
new Walbro pump on frame rail pass side
3/8 inlet line from tank to fuel rail (all new and high pressure line)
3/8 return line from regulator to tank (all new)
1 filter after the pump (new)
new sending unit in tank (sock removed)

I think I'm getting air in the system but can't tell if that's my entire problem.

My return line in tank is not below the surface of the fuel so it's "falling" when returned. I believe that's creating aeration in the tank when the fuel level drops even slightly. Then the pump receives air bubbles causing pressure to drop significantly and thus not enough flow for the injectors under heavy load.

Symptoms: Very loud fuel pump, lower than 42-45 psi at rail like the regulator is designed for, falls on face and leans out under heavy acceleration / load.

I'm planning to extend the return line in tank with a piece of hose and a weight to keep it below surface. Is there a trick to dispersing the fuel out of that hose to keep it from agitating in-tank fuel more than necessary? Like a sock or a perforated tube?

If anyone else is running a walbro pump, have you had trouble with it making an unholy screaming sound when you're low on gas?

Does anyone have a different brand / style of pump they can recommend for a mostly stock setup like mine which would be less prone to cavitation when aerated fuel is introduced?

[snj8198]

hi mtm,

Fuel aeration is exactly the problem you described. I too experienced this issue with my stock tank when i first installed my Pro Flo system and allowed the returning fuel to "splash" back into the tank. Here's what i did to fix it.

Pull the stock sending unit, drill and weld in a 3/8" hardline for the return. I bent the hardline at about 60 degrees at roughly 2/3rds the distance down the tank and made it long enough to reach within an inch or two from the bottom of the tank all the way to the driver's side corner. This is so to keep the discharging fuel as far away from the pick up tube as possible. I also used a sock on the discharge to help minimize the returm stream. This may be more effective at low fuel levels if it's helping at all. You may experience some venting issues that will need addressing as well. My fuel cap needed releasing on occassion until through trial and error i managed a vent set up that seemed to alleviate the issue.

Remember these pumps are better pushers than pullers so hopefully you have it installed as close to the tank as possible. Also, you state you have a clean tank, but regardless, either install a 100 micron filter (or better) before the fuel pump or reinstall a new sock on the pick up tube. The filter after the pump should be a 10 micron. It doesn't take much to clog the injectors creating issues.

Also remember, the stock tank does not have a sump or baffling so you may run into performance issues at very low fuel levels, especially if you are driving in a way that really gets the fuel sloshing in the tank. I figured it was best to never run the tank to less than 1/8" full.

I hope I helped you a bit here. Good luck with it and have fun. -steve

[mtm_seven]

Great info, Steve. Thank you for the reply.

I'll mess around with it this weekend and see if I can duplicate your setup.

[mtm_seven]

I added an extension to the return line and had moderate success but I still think that since my return line I.D. is smaller than the inlet that gravity feed just can't keep up with the flow - basically, unless I add a low pressure pump upstream to feed the high pressure pump then I'm looking at a fuel starvation issue every time I get below half a tank. Problem with that solution is a low pressure pump can't keep up the same volume.... starvation again.

My pocketbook is trembling at the thought of dropping $700+ on a custom tank with internal pump but that looks like the only dependable solution.

I hate that I spent so much time and money trying to rig the stock tank to work.

[snj8198]

Originally Posted by mtm_seven

I added an extension to the return line and had moderate success but I still think that since my return line I.D. is smaller than the inlet that gravity feed just can't keep up with the flow - basically, unless I add a low pressure pump upstream to feed the high pressure pump then I'm looking at a fuel starvation issue every time I get below half a tank. Problem with that solution is a low pressure pump can't keep up the same volume.... starvation again.

My pocketbook is trembling at the thought of dropping $700+ on a custom tank with internal pump but that looks like the only dependable solution.

I hate that I spent so much time and money trying to rig the stock tank to work.

I experienced the frustration of wasted time and effort on the stock tank as well. I had fuel supply issues, wiring issues, fought and finally tossed the supplied ignition amplifier, and the shutter wheel and hall affect conversion was a joke. I finally pulled the system and it's in a box until i flat bed the truck and do a proper fuel tank and system for mine.

I'm sure you can find a good efi tank for less than $700. Well, maybe you will if you spring for a good in-tank pump, filter, and all braided lines and AN fittings.

[mtm_seven]

Definitely a joke..... I already evicted the entire Edelbrock computer and ignition crap - back to a standard HEI and using a FAST XFI computer with wide band O2. +$800 on top of the edelbrock system. It does automatically learn and tune itself. Amazing improvement over the other system.

It's. so. damn. close.

Seriously, the truck does exactly what I want when I have a full tank of gas and the fuel delivers. If I can get a consistent 45 PSI to the rails for the duration of a tank of gas, I'm more than confident it'll be whipped. Issue is, that delivery is a pipe dream from the stock tank drawing the volume necessary from a gravity feed going up to the top of the tank and back down to a high pressure pump. Damn shame I didn't come to this realization sooner.

Here's the tank I'm pondering...
http://www.azproperformance.com/Boyd...ill-14004.html

[Orange Crate]

You might find something a little more affordable here:

http://www.tanksinc.com/index.cfm

[mtm_seven]

Thanks for the additional option, Orange Crate.

Here's my breakdown:

Tanks Inc - EFI tank + sending unit + Walboro pump + shipping = $580 (still need mounting hardware

Boyd Inc. - EFI tank + sending unit + Aeromotive pump + shipping = $718 (19 gallons)

Fuel Cell Guy - EFI tank + sending unit + pump + shipping = $725 (18 gallons) not sure of pump brand

Performance Online - these guys were high as a kite. No thanks.

~$140 more for the Boyd tank that fits well, tapers up and has the highest capacity seems like the one to choose. None of the options seem like a deal at all though.

Does anyone else have input here?

-M7

Originally Posted by Orange Crate

You might find something a little more affordable here:

http://www.tanksinc.com/index.cfm

[Gumby]

or a $20 electric FP from auto zone mounted to the top of the tank as a feed pump, It will push all the GPH needed to the FI pump, that will then boost the pressure as needed.

GPH is all that matters for the feed pump, FI pump will build pressure as needed.

less ya like spending money as a TBI FI system doens't need all that, now if you spent real money on a real MPFI system................ go that extra mile.

[haysonj]

Originally Posted by Gumby

or a $20 electric FP from auto zone mounted to the top of the tank as a feed pump, It will push all the GPH needed to the FI pump, that will then boost the pressure as needed.

GPH is all that matters for the feed pump, FI pump will build pressure as needed.

less ya like spending money as a TBI FI system doens't need all that, now if you spent real money on a real MPFI system................ go that extra mile.

This is what I did with my Pro Flow system and have had no problem. I have a switch on the dash and only run the pump if I'm below a half tank or when switching tanks

[snj8198]

These tanks seem like nice quality but have you ran into anything larger in capacity? I may ride your research coat tails m7, but i would prefer a minimum of 25 gallons.

[mtm_seven]

Fuel Cell Guy claims he will custom build one to your specs - research shows he's reasonable. If the intended truck is pretty tall, you could just have him make the regular 67-72 tank deeper.

Originally Posted by snj8198

These tanks seem like nice quality but have you ran into anything larger in capacity? I may ride your research coat tails m7, but i would prefer a minimum of 25 gallons.

[Gumby]

Originally Posted by snj8198

These tanks seem like nice quality but have you ran into anything larger in capacity? I may ride your research coat tails m7, but i would prefer a minimum of 25 gallons.

Just sump the stock tank..........

[haysonj]

Does anyone have a different brand / style of pump they can recommend for a mostly stock setup like mine which would be less prone to cavitation when aerated fuel is introduced?
I used the pump that came with the Pro Flo also changed my suction sending unit to the 3/8 that comes with big block trucks I then put the return in with a steel tube bent and installed like the instructions show. I don't have any problem unless I let it get below a 1/4 tank. I have a 450 HP 383 with the 4 barrel pro flo

[snj8198]

Fuel Cell Guy claims he will custom build one to your specs - research shows he's reasonable. If the intended truck is pretty tall, you could just have him make the regular 67-72 tank deeper.

Thanks, I'll look into this.

Originally Posted by Gumby

Just sump the stock tank..........

Originally i considered this or atleast adding baffling, but i want the cab space where the stock tank sits. So when i make the switcheroo i'll convert back to the EFI and therefor appropriate tank.

[mtm_seven]

Just dropped $712 on the Boyd's tank.

I decided to go that route for a few reasons...

• safer to have tank out of cab
• sump in cab would be loud
• lift pump for low fuel is not a long term solution for me
• more space in cab
•leave the filler neck for a stock look
• no more gravity feed low fuel issues
• no more frame-rail mounted external pump in harm's way
• slightly more tank volume
• brand new construction no contaminates in new tank
• baffled design will resist starvation when cornering under low fuel occasions

I spent this much so far... hate to skimp on something so crucial.

[mtm_seven]

Oh, and I went with the Boyd's because FCG was 4 weeks out on production and I'm a generally impatient guy. Otherwise, I think both tanks are equally good.

[Gumby]

some reason your leaving the filler made me think of it, where it looks like the stock tank is there but the filler just fills an under bed tank. And in side it looks to be there. flip seat forward and whole side of the tank opens as storage.

[snj8198]

what's your plans for a filler neck location?

[mtm_seven]

Originally Posted by snj8198

what's your plans for a filler neck location?

I'm still scratching the noodle on that one -

thinking about cutting out a section from the bed, welding some supports underneath the hole and using neodynium magnets to hold it in place when not removed for filler access. Maybe a 6"x6" square.

Or, same hole but with edge banding for strength and a spring loaded hinge.

Or, a marine grade filler with a rubber hose connecting to the tank... issue there is getting it to seal in a reassuring way.

http://www.monstermarinestore.com/pr...d=871&incat=40

I'm probably not gonna be hauling cord wood or rocks with this thing. Therefore the solution really just needs to be cosmetic.

[snj8198]

Well take lots of pics of your install so i can cheat.. er I mean check you craftsman ship out.

[Super73]

Below are examples of what I have run in my truck. Each set up never showed an issue with aeration.

Dual in line Walbro set up with regulator before rails:
-10 from cell
-10 to dual -8 Y connector
Dual -8 filters
Dual -8 to dual walbros
Dual -8 back in to a -10 via a Y
Single -10 in to an Aeromotive A1000 regulator
-10 split via Y in to -8 going in to the rails
From of the rails were tied together with -6
Return was a -6 mounted top of cell allowing fuel to fall.

This system was designed to have 1 pump on at all times and the other came on when I armed the N20. The issue I ran in to was the regulator could not control the fuel flow fast enough during N20 use and it would cause a fuel pressure drop when the N20 would first come on causing either a lean condition or my fuel pressure safety switch going haywire turning N20 flow off and on really fast like a N20 controller pulsing the solenoids.

Dual Walbro set up with regulator after the rails:
Dual -10 feed
Dual -8 filters
Dual Walbros
Dual -8 to -10 Y
-10 ran just prior to rails and got split back to dual -8 via a Y and fed both rails
-4 off the front of both rails in to the regulator
-6 back to the cell mounted at the top of the cell allowing fuel to fall.

This cleaned up my lean spike during the N20 hit.

Both systems above, the N20 was fed off the fuel rails. By moving the regulator after the fuel solenoids worked a lot better.

On both the above, the -6 return was mounted in top right hand corner of the cell furthest forward corner shooting fuel towards the left side of the cell. My second fastest pass with the little motor (347) I ran out of gas on the return road. If I had seen aeration, I feel it would not have run that good.


Current fuel system supplies a LOT more volume yet still works fine with a -6 return:
-12 from cell
-12 filter
Weldon 2035 fuel pump (-12 in -10 out)
-10 filter
-10 to -8 Y just prior to the rails and feeding rails
Dual -4 off rails in to A1000 regulator
-6 return resides next to the -12 inlet at the bottom back center of the cell.

N20 is still pre regulator

System has proved to work well with 91 gasoline, a 50/50 mix of gas and E85, straight up E85.



As far as fuel pump noise. Walbro's get a lot louder when run out of fuel and they burn up fast with out fuel to keep them cool.



I know there is probably more info above then you want/need but it might be useful.
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[mtm_seven]

Thanks for the deluge of info, Super73. You are def out of my league on volume - I'm just trying to make a truck go to the grocery store and back. (maybe not counting my ETs while shopping) Ha!

So I am gathering the fittings for the job and am wondering about filter placement... the in tank pump will have a sock but I'm keeping an in line high pressure filter as well. Is it better to have that near the tank, in the middle of the system or at near the fuel rail?

In regards to maintenance access in my application, filter placement at the rail would be the easiest location, near the tank the most difficult and in the middle, well, the middle.

Question is: Will having the high pressure filter near the fuel rail cause a significant surge in pressure due to the volume of filtered and pressurized fuel being lower than if I had several feet of it between the filter and rail? Or is the distance from the end of the filter to fuel rail mostly negligible?

I feel like I worded the question poorly. Hopefully someone understood.

[snj8198]

Basically you're wondering if the external fuel filter placement will affect fuel pressure and/or volume. Good question.

[mtm_seven]

Originally Posted by snj8198

Basically you're wondering if the external fuel filter placement will affect fuel pressure and/or volume. Good question.

Yep. Like on my '03 and '96 they have the filter under the cab - in the middle.

I heard (def didn't touch) that Do**e trucks have a filter in the tank only.

Wonder if they aren't in the engine bay for safety reasons or system performance.