intank surge tank setup...

[ed]

the jza80 is pretty bad in managing fuel surge below 1/4 tank

the stock tank has an ice cream container sized pot installed on the tank floor into which the main fuel pump pickup and fuel return sit. the pot has an inlet/outlet duct on the side, about 1" square in profile, which runs 270 deg around the pot itself to help try and prevent directional surge (which doesnt work )

so, i was thinking of blocking this duct, thus making the pot non drainable around its base. i was then thinking of running a spare std efi pump, with its pickup outside the pot on the floor of the main tank, feeding the pot. the pot would then have to spill over the brim to empty - but atleast it would remain full (ish).

what are peoples thoughts on this kind of setup? ok to use the spare efi pump as the 'lift pump' in this assembly? issues with it running without pressure on its output line? issues with it potentially running dry as the fuel sloshes around the main tank?


im just trying to come up with some basic scheme, preferably all remaining intank, to help combat this surge.

cheers
ed

[kingmick]

Id imagine it would be less hassle and cost to fit a surge tank?

[Lambolica]

This might be the worlds biggest PITA and I have no idea of its merits but i did see somthing not unlike what you are talking about.

Hold on to somthing this could get rough....

the setup consisted of a cylinder that slotted in where the factory pump slots in and this acted as the surge tank. (for you you can replace this with your ice cream container). Inside this sat the Fuel pump to the engine in the conventional fashion, return line also dropped in here.

Contained also in the surge tank was another lift pump that was fixed to the wall and connected to a pipe that ran external to the surge tank. This is where the fun starts... this line was connected to a fancy "Rail" for want of a better term that had 5 line going in to it. 4 of the lines ran (in brass pipes to the 4 bottom corners of the car and the 5th was a return from the surge tank (or possibly the return)

I gave him the idea to do this for a school project, and he went ahead and did it.

Cutting all of the crap out of it you could possibly use a lift pump in a similar fashion and draw fuel external the surge tank.

I have no input to using an old intank pump for a lifter pump but am curious to know.

Cheers
Simon

[Lambolica]

Sorry I kind of realise that post is in no way relevant to your question.... except that it may solve the lift pump running dry if his "rail" in fact works. In which case you wouldn't need a surge tank at all.... I'll have to have a chat to the young bloke and see if he ever tested it.

Could you run a fuel pressure regulator on the outlet side of the std pump?

[kingmick]

Oh no, now we are going to have fuel accumulators! lol

[ed]

now theres an idea! lol !

no, seriously, i guess the crux of this question is whether or not the spare efi intake pump i have can be used as an intank lift pump for the pot - considering it will likely surge sometimes, and also the lack of resistance to flow...

[TheToyman75]

Ed,

The key here is to make sure your "lift" pump has enough flow to support your main pump. If its high or low pressure really does not matter so yes an EFI pump can be used.

With your return line feeding the "icecream container" on the bottom of your tank what you are suggesting will help. The problem you ill have is during any form of track work or spirited cournering. The contanier on your tank floor is not that big and with its completely open top it will still allow fuel to surge and spill out. Your lift pump wont have to run dry for long for your main pump to surge.

If your going to use an intank pump you can use an intank surge tank. The pump access on your tank is pretty big so you would be able to to put a reasonable sized alloy canister in from the top. The tank also has a deepish spot where the pump is from memory. (Its been a while)

If you mount your "lift pump" on the base or bottom side of the canister it will sit on the bottom of the tank as it does now (preferably inside your "icecream container" then you have that feed the alloy fuel canister which contains you high volume main pump. ( mounted inside) The return line returns to the fuel canister and a 3/8 hole in the very top of the cannister allows for your overflow. Your cannister needs a lid but it can screw on as it doesn't need to be fuel tight as its inside your tank making it possible to be made at home.

Once the system is primed it will be quite effective just perhaps a little less than ideal on volume. To ensure its always primed you could try set a 3 or 4 second time delay on your main pump starting so it always starts just after your "lift pump"

[clubagreenie]

In relation to in tank rails or multiple pickups, what stops the pump running dry during surge since some of the pickups are going to be uncovered?

[Lambolica]

In the case of my "mates" project he used a (in his words) "floating valve" at the ends of each line. In short if the end of the line was submerged in fuel it could draw fuel. if it was open or partially open to air the line was locked off, at the "rail end" he was using some 1 way valves to lock off the "empty" lines.

The idea came about because he was listening in to his dad and I talking about surge tanks, and the way V8 supercars run 4 lift pumps in the corners of the tank, he wanted to achieve the same thing but without the additional pumps. The idea works in theory, but I don't think his valves would work without some more R&D

[thechuckster]

ed: you'd probably want a lift pump like the intank pump found in early EFI commodes (with the external bosch EFI pumps).

[ed]

hmmm, they run a submersible intank lift pump?

whats the differece between that and running the spare EFI pump (the OEM supra one i know have spare) as the lift pump?

[cambelt]

dont run the intank lift pump from a commodre they last all of about 100000klm and die , toyota supra lift pump running thru a mx 83 resister = 400000klm , no joke

[thechuckster]

only reason i can think of is the commode pump is a low-pressure high-volume pump. An EFI pump is still a low-volume pump whether it's running restricted or open ended.

Using things in opposition to their original design function is risky.

My gut feeling is also that you'd over-speed the EFI pump motor running it with an open end.

As for running one at ~9v (using an MX83 resister) i would have to call shenanigans (spell?) for it lasting 400,000 km. And which Supra actually uses a lift pump? i thought they were all in-tank pumps.

[cambelt]

Well how come MX 83,s standard last 400000klm on the original pump , im telling you that if the pump runs on 8 volts it will do 400000klm.
That excludes dirty fuel or contaminants.
A jza 80 intank efi pump with a resister in series with it would make a perfect lift pump into a surge tank.
Dave

[thechuckster]

MX83 would be an in-tank EFI pump