Fuel slosh

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entirelyturbo
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Fuel slosh

Post by entirelyturbo »

It took me forever to notice, but I recently observed that my car dropping too low at idle, close to stalling, only happens under these conditions:

1) When I'm turning somewhat briskly
2) When I'm a quarter-tank or lower on gas

If I'm coming to a stop while going straight, or I have over a quarter-tank, I have no such problems.

Logic can only suggest that I'm having fuel slosh; when the fuel gets low enough and I'm turning a little fast, the fuel sloshes away from the fuel pump, thereby very temporarily starving the pump, and thusly, the engine of fuel.

I remember very vaguely from an old SCC magazine, when they were working on their turbo 2.5RS, that they were experiencing the same problem albeit with anything less than a half-tank. I don't remember what they did to take care of it though.

I don't know myself what I could do without ripping out the fuel pump and sending units, or worse... dropping the tank.

But does anyone have any ideas or suggestions?

Besides filling up everyday so I always have a full tank :lol:
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Legacy777
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Post by Legacy777 »

Not saying that isn't your problem, but there is a bafel plate or container that surrounds the pickup area of the pump. Sort of like a mini basin for the fuel.

How fast are these turns?
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vrg3
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Post by vrg3 »

Whenever I make a fast sharp right turn and accelerate hard coming out of it with less than half a tank of fuel, I get fuel starvation a couple seconds later.

This started happening only after I installed the 16G and the 2JZ-GTE fuel pump. I used a junkyard fuel pump assembly so I could rig up the Supra pump off the car, and I kind of wonder if maybe the jet pump on this junkyard pump assembly is faulty.

Or maybe it just can't keep up with the increased flow requirements. It's not meant to flow that much; just enough to keep the fuel warning light from coming on, pretty much.

I was actually thinking of getting maybe one of those little low-pressure electric fuel pumps used for carbureted applications and putting it in the jet pump hose, continuously moving fuel from the left side of the tank to the right. The only problem I can see is that it probably wouldn't like to be run dry when the fuel level gets lower.

A swirl pot or surge tank is The Right Way to resolve this, I think.

Josh, you don't happen to have a picture of what you're talking about, do you? Maybe my Supra pump isn't fitting in that little basin.
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Post by THAWA »

Fill up every other day :)
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Post by Legacy777 »

Unfortunately, no I don't have any pics. It's nothing fancy, just a surround type tub thing with holes in the bottom to allow fuel to come in.
Josh

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vrg3
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Post by vrg3 »

Hmm... I'd be able to see it if I removed the fuel pump and shone a flashlight down in there?
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entirelyturbo
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Post by entirelyturbo »

These turns aren't exactly 2g-force hairpins, but let's just say making a 90º corner at 20mph.

This isn't a very early indication of a fuel pump on its way out is it? Could the fuel still be there and the pump is a little too weak to pick it up? I've never replaced it, and I've had the car since 90k, so I'm fairly certain it's original.
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vrg3
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Post by vrg3 »

It's possible... or maybe the sock filter is getting clogged?
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Post by free5ty1e »

yeah, them socks get pretty dirty.
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Post by Legacy777 »

vrg3 wrote:Hmm... I'd be able to see it if I removed the fuel pump and shone a flashlight down in there?
Yeah you should be able to see it if you pull the fuel pump. Assuming the fuel level was low enough. You should be able to see it on an empty/near empty tank.
Josh

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2020 Outback Limted XT

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Post by vrg3 »

Cool, next time I run my fuel level really low I'll pull the pump and see if the sock is seating inside that little area.
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entirelyturbo
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Post by entirelyturbo »

vrg3 wrote:It's possible... or maybe the sock filter is getting clogged?
I was wondering about that too...

I probably won't do anything unless the pump kicks the bucket though... I'm too lazy :)
"Der Wahnsinn ist nur eine schmale Brücke/die Ufer sind Vernunft und Trieb"

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