[JrZook]

Righteo. So I run a G16MPFI in my sierra with the stock tank and stock pickup to a chassis mounted inline VL pump. I tend to do a lot of rather long road trips so using the tank to its absolute minimum is key.

Now this setup is quiet descent 80% of the time but I do start running into hiccups once the level gets to 10L and less (fuel slosh around corners, braking etc). On dead flat ground I can get around 5L till she cant pick up anymore. That 5L or so could be up to ~50km so any improvement is a significant gain for me anyway.

I know a low pressure pump feeding a surge tank then to the HP pump is the best solution but id rather try and keep the simplicity of the single pump.

So I have a spare tank with minimal dents that im keen to modify for a better pickup system. Note this tank have been sitting open for a few years so I have no issues cutting and welding this one. The idea i have is to get rid of the original metal pick up and replace it with a length of flexy fuel line with some sort of weighted pickup on the end of that.

Theory is that the weighted end on the flexy line will be free to move around inside the tank, gravity assisted and thus find the deeper fuel side.

Another modification I had in mind for improved low level pick up was to cut a section of the tank out along its width and weld in say a 75x20mm channel piece (or what ever fits in-between the tank and tank guard) to act as a well for low level fuel collection with the weighted pick up running in that.

Thoughts?

[PJ.zook]

You could run a lower spot as you suggested for fuel pickup, or you could make an internal swirl pot. Maybe use some truck exhaust cut like 4inches high, then put a couple of small notches in one face, and weld that notched face to bottom of fuel tank where it will sit surrounding the fuel pickup.

[xedent]

Yeah i dont know what the coily tanks look like but is there a way to modify the normal one so you can use a vitara pump ?

[Fatzook]

xedent wrote:

Yeah i dont know what the coily tanks look like but is there a way to modify the normal one so you can use a vitara pump ?

Yeah but it involves alot of fabrication, so IMO its not worth it.

Dan, the weighted hose will have longevity issues and starvation issues just the same as you get now, as I doubt the hose wil move as freely as you hope it to.

Really the only viable solution is the one that exists already in every other EFI tank. Baffles and a swirl pot. NFI how you will go doing this to the sierra tank.

Personally I'd be fitting an external surge tank, OR getting a coily tank and slapping a vit pump in.

This just seems like the very long way around.

[reallyuted]

WARNING............. DONT just think that a fuel tank that has sat for years is safe to cut and weld!!!!! fuel can get impregnated in the seams!!! i did my mates tank(after intensive cleaning and prep for cutting and welding) and welded a drop in swirl pot and vitara pick up with pump. pretty much just copied whats in the lwb vit tank.

[Fatzook]

Ditto ^^^^

I filed my tank with water and it still caught fire when I welded it

[reallyuted]

^^^^^ thats what i did but also flushed it twice with detergent

[Fatzook]

mine was flushing continually for 45 mins. In the end I just had Rusho stand there with a fire blanket incase I needed to be 'put out'

[SuziBlu]

Inert gas is the answer.

No matter how much you flush a high vapor fuel tank, some will stay, so, wash/flush whatever, but, before you strike a spark near it, fill the tank with an inert gas, ie, C02 or N.

N is better, but C02 is probably easier to come by.

If the tank is filled with either, there is zero chance of ignition, you may want someone with you who can keep the tank topped up with the inert gas.

Main thing is to exclude all 02, H20 is an oxidant.

[ajsr]

I made and repaired tanks for brown davis back in the day.

the way to weld a tank is not to flush with water but to fill the tank with CO2, preferably with it continuously flowing into the tank.
we used weld them with the dreggs of petrol still inside the tank.
Ive beem told that migshield or equiv works just fine too but ive never tried myself.

we used to do those 1/2 tanks for LPG by putting a hose with co2 into the tank and then cut them in half with a 9" and weld a plate over the hole.

be warned I do not recommend this to anyone unless you know what your doing.

if it were me I would weld a small surge tank into the base of the tank, If you know you wont bottom it out.

[Fatzook]

Yeah I know this, but I was being cheap and didnt want to purge $150 of gas through a $50 tank.

[ajsr]

a block of dry ice in the tank works too.
you dont need massive amounts of gas in the tank just fill with gas and allow a small amount to keep flowing or tape it up.
the gas is heavier than the surrounding air so it stays put pretty well.

[SuziBlu]

lol yea, I can dig that.

A bottle of N would not cost that would it ? you don't need a G size.

Believe it or not, you can weld a tank full of diesel.

Quite often on boats fuel tanks will split, mostly pulling the top off, bad weather, fuel crashing against the top, splits along the welded seam. What happens is, wait for a really calm day, press up the tank, (fill it to the top for u landlubbers) and weld away, even if its a down seam and the seam is weaping it is fine.

I do not think that it contaminates the fuel in any way, but, remember mostly these tanks are over say 10M3 and so if there were any contamination, it would be so diluted that even the most sensitive screening would probably fail to find it.

[rick1970]

ajsr wrote:

the way to weld a tank is not to flush with water but to fill the tank with CO2, preferably with it continuously flowing into the tank.
we used weld them with the dreggs of petrol still inside the tank.
Ive beem told that migshield or equiv works just fine too but ive never tried myself.

we used to do those 1/2 tanks for LPG by putting a hose with co2 into the tank and then cut them in half with a 9" and weld a plate over the hole.

be warned I do not recommend this to anyone unless you know what your doing.

There was a local engineering company here that welded a 'properly cleaned and flushed' fuel tank for a customer. After the explosion they got the nickname 'Boom" engineering

Be carefull.

[Rusho]

Fatzook wrote:

Ditto ^^^^

I filed my tank with water and it still caught fire when I welded it

That was a fun day