Pump-to-pump line distances?

[Begle1]

So my current homebrew fuel system is almost done.

I got 6 feet of 1/2" braided stainless from the lift pump outlet to the transmission cooler, then 6 feet of 1/2" braided stainless from the transmission cooler to the remote mounted filter, then 6 feet of 1/2" braided stainless from the remote mounted filter to the injection pump.


Considering that the stock line was about three feet long, and my new system is going to multiply the volume of that by about 50... There shouldn't be any problems with that, should there?

[Ace]

Why do you have a cooler between the LP and filter?

[Begle1]

To keep my IP cool.

[soggy]

Wouldn't it be better off in the return line?

[Begle1]

Maybe, except I don't want to mess with the return line yet. That is how things are typically done... My cooler should last at 15 PSI, I hope.

[Ace]

Wouldn't it be better off in the return line?

Yes, because that is where the fuel is the hottest, after running through the VE and injectors. So that is where the most potential for heat transfer exists, because the temperature differential is greatest and there is less fuel flowing slower allowing more time for heat transfer. The fuel will eventually become hotter even if you run it through the cooler on the supply side, because you are still dumping hot fuel into the tank and by the time it gets to the cooler it is relatively cooler already due to mixing in the tank and is traveling faster under more pressure, so less heat transfer happens.

Your fuel temps over time will rise higher than they would with the cooler in the return line.

[Begle1]

But if any heating of the fuel occurs between the tank and inlet of the injection pump, and the cooler is on the return side of the injection pump, then the injection pump will see hotter fuel than if the cooler was on the return of the injection pump. What's the point of cooling fuel after it gets to the most sensitive part of the system? Sure, over a prolonged amount of time the cooler would do the most good on the return side, but I only go over 2500 RPM for short periods of time anymore now that I have overdrive.

And, since you have math on your side, with the cooler on the supply side I will be able to notice when it gets a leak.

[Begle1]

Well, I fired it up, no obvious leaks.

I have to hit the primer bulb about 200 times to get the filter filled up. That's pretty awesome.

I didn't find a very good mounting location for the filter. I had to mount it between the frame and the bellhousing on the driver's side. It's nice and cozy there and doesn't get in the way of anything, but it's the very bottom part of the system. So filter changes are going to suck. I might need to work in a couple ball valves.

The little water separator bowl on the bottom is just asking to hit something too. Especially the stupid little drain nut that you thread UP to open, so it sticks about an inch farther down than anything else on the bottom of the truck. If I keep it there I might need to carry a replacement for the inevitable road hazard.


Um, the little clear water separator bowl on the bottom is supposed to be full of fuel at all times? I wasn't expecting that.

[soggy]

what are the details on your system? Pump? regulator? Just curious.

[Begle1]

I just have a low-pressure piston lift pump. I turned the stock tranny cooler into a fuel cooler now. A big 10-micron Racor fuel filter/ water separator. Basically I had a bunch of stuff in my shed and I'm moving so I figured I oughta install what I could.

After the lift pump it's all 1/2". Of course, it's 1/4" coming out of the lift pump and 1/4" going into the injection pump, so I'm sure that the 1/2" stuff is going to do a lot of good.

Should be a cooler, better filtering system now, at any rate.