This is exactly what I told him when he called me about it all, but FAST is saying in the bottom.
Fuel Injection
- Thread starter oino
- Start date
This is exactly what I told him when he called me about it all, but FAST is saying in the bottom.
hmmm... errrrr
Ok. Fast, Fastmanefi, and speedway has all told me it needs to go in the top.
Their reason is that the return fuel is at a low presure and will have problems pushing back up into the tank against fuel.
I don't know.
ok a quote from someone on another site.
"You can plumb the return line in anywhere it will fit (other than below the typical full gas level of the tank, because it will induce back pressure into the return line).
Return fuel flow (or volume) is generally not that high, and the pressure isn't that high (pressure and volume are two different things)."
"You can plumb the return line in anywhere it will fit (other than below the typical full gas level of the tank, because it will induce back pressure into the return line).
Return fuel flow (or volume) is generally not that high, and the pressure isn't that high (pressure and volume are two different things)."
Return volume is almost as high as feed volume, since the regulator returns most of the fuel to the tank during routine (i.e., not WOT) operation. And regardless of the return pressure (which will depend solely on volume and flow resistance, and will normally be quite low), it would take more pressure to raise the fuel to the top of the tank than the bottom. The fuel in the tank has nothing to do with it. That's, well, hydraulics 101. I wish all vendors and manufacturers were reliable sources, but they are wrong on this. I've been running my setup for 20 years with bottom return and have used various pumps and regulators, including the latest Fuelab variable-speed pump. I can assure you it works fine, and, because of the aeration and static electricity issues I mentioned earlier, bottom return is the best engineering answer. That said, top return is used by many rodders and tank makers; it's convenient and avoids the possibility of a leak at a bottom return. And most OEMs use top return to simplify manufacturing (feed, return, pump and filter are combined in one unit that plugs into the top of the tank). Bottom line (another pun!): either way will work and I wouldn't lose any sleep over this.
Wild Mango
Member
Each to their own opinions. In the Midget the return always goes in the top of the tank because its at atmospheric pressure. The pressure regulators we use read atmospheric as reference pressure, and any backing up on the tank return tends to manifest itself as a rise in delivery pressure. In a full mechanical system that we are obliged to use this changes the fuel mixture ratio. However, in a "smart" ECU driven system, the controller compensates for delivery pressure variations by changing the squirt duration and no problems at all.
I don't recall any problems with aeration, and of course the return oil goes into the top of the tank for just this reason, to make sure any aeration stays at the top where it has the shortest path to the atmosphere. As PotvinGuy says, either will work, its just whatever blows your dress up at the time.
I don't recall any problems with aeration, and of course the return oil goes into the top of the tank for just this reason, to make sure any aeration stays at the top where it has the shortest path to the atmosphere. As PotvinGuy says, either will work, its just whatever blows your dress up at the time.
fordsbyjay
Active Member
I have read not to do this because it can aerate the fuel at the outlet which can cause pump starvation. I have not tried this myself though.
Does the return have a drop tube, or does it just dump right in?Accel Says the same thing for their DFI Gen VII system. My EFI rated fuel tank has the feed, rollover vent and return in the top of the tank.
An excellent design. Who built that, Grant?
It's an RCI fuel cell certified for EFI. I don't remember where I got it.
It fits perfectly in a 20 inch bed and holds 14 gallons of fuel. I believe the fuel feed fitting is -10AN and the return and vent are both -8AN.
finally got my fast system today.
Here are some picks.
When I opened the first box and got the t.b. out and seen the wiring on it. I thought, damn I got this. This will be easy. Then I opened next box.
What the hell. They should make a tbucket version of this thing. lol.
This will be fun.
Here are some picks.
When I opened the first box and got the t.b. out and seen the wiring on it. I thought, damn I got this. This will be easy. Then I opened next box.
What the hell. They should make a tbucket version of this thing. lol.
This will be fun.
Ah, you got the new 2.0 version with the color touchscreen and spark control. I'm gonna go slap my crummy old 1.0.
If you have any questions re wiring, I've done it and can help. Check my blog http://www.tbucketeers.com/threads/big-redo-of-the-old-bucket.13677/ for pics and verbiage.
If you have any questions re wiring, I've done it and can help. Check my blog http://www.tbucketeers.com/threads/big-redo-of-the-old-bucket.13677/ for pics and verbiage.
fordsbyjay
Active Member
I'm jealous. I wanted that unit but they were not available when I bought my HPefi from Holley. I should have waited as I have not used the holley yet. DOH!
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