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I have a 99 TA with boosted 5.3 eventually hitting 14psi, just recovering from a burnt piston (will update that thread soon, looking good so far!)
Just installed a brand new Racetronix Fuel pump and all is well, but I had one helluva time getting that small hose on the venturi at the bottom of the reservoir. It's on, and passed the light "tug test" but am concerned.
I have trap door mod so am able to check it from time to time, right now bucket seems full and having no symptoms even with very low fuel level, have not gone into BOOST yet though.
So my questions are:
Does the small hose have a lot of pressure in it? I know it runs off of fuel pump pressure but it is continually relieved through the venturi as shown in this diagram, I am hoping that means it's not a lot of working pressure in that hose.
And secondly, what would be the symptom I'd see if that small hose popped off of the venturi nipple at the bottom of the reservoir? Would that generate low fuel pressure immediately and possibly leave me stranded? I understand that the bucket won't fill (or will it LOL? Hose dumping fuel straight into the bucket?). EDIT: Just double checking my logic, the loose dangling hose would NOT keep the bucket filled because the pump doesn't draw from the tank, the pump draws from the BUCKET. Still curious about this though if anyone's had that happen.
I've always wondered how it works too. That's a neat diagram you found.
It looks like maybe that primary umbrella valve (item 4) is the main inlet of fuel into the bucket. And I'm guessing the fuel flow from the diverter pipe (item 1) is what's opening and closing that valve to regulate the height of the fuel column in the bucket. Without the diverter pipe, I think maybe that valve stays closed and the fuel pump will be starved?
There are at least three good reasons to have a full column of fuel in that bucket. One is it cools the fuel pump. Another is it provides surge capacity when needed. And it keeps a continuous head of fuel above the pump inlet during hard driving. There are no baffles in the fuel tank, the bucket itself is the "baffle".
It looks like maybe that primary umbrella valve (item 4) is the main inlet of fuel into the bucket. And I'm guessing the fuel flow from the diverter pipe (item 1) is what's opening and closing that valve to regulate the height of the fuel column in the bucket. Without the diverter pipe, I think maybe that valve stays closed and the fuel pump will be starved?
From the research I have been doing, and I could be totally wrong on this... I think that #4 is more like a check valve like #6. If the tank fuel level is high enough, it'll just flow into the bucket naturally flooding the bucket up to the level of the tank regardless of the little hose through those two valves. But in cases where the tank fuel level is lower than the desirable bucket level, the flow through the venturi from the little hose causes a suction effect and draws fuel inwards through #4 to get the level up in the bucket, kinda like how air in a carb pulls the fuel with it through a jet.
Still wanting to know what happens if my hose pops off my nipple down there (that sounds dirty LOL).
Trying just one bump here.. wanting to know what the symptom/result would be if that little hose pops off so I know what to look for, and also if it'll leave me stranded. Nobody had that hose break or pop off?
Also want to make sure it's good before I seal up my trap door LOL.
I guess if nobody knows, I'll just leave trap door open until I do some tuning and get a few wide open blasts completed, then run the tank down and eyeball it and make sure that hose is still there and bucket is full at least at that point and then just seal it up and see what happens.
Could one install the big, aftermarket pump IN the bucket, with a Holley Hydramat sticking out the bottom, and let the RETURN fuel drain into th bucket for "cooling" ?
That would be simpler, but the question is, would the Hydramat function as a surge tank, and also adequately to burn the last gallon out of the tank ?
The largest pump I know of with a venturi setup is the Racetronix 340 L/hr. And specifically the Racetronix pump. No other brand has anything above 255 L/hr that I've seen.
I'd be interested to know if somebody has found something different.
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Racetronix Fuel Pump question 
