superheated fuel

DTanklage

DTanklage

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Jan 2, 2009
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took a 180 gph fass pump and got rid of the internal reg

got a sumped 30 gal fuel tank

so, i got the weight of all that fuel pushin into what was a 180 gph pump

have a 100 micron aeromotive prefilter that does not offer any measurable restriction

-8 line to a 2 micron mongo napa filter that will hopefully cut the volume down some

but then the fuel flows thru my p-pump right thru a bypass reg and right back into the tank

the way i plumbed it it is boost referenced so there will always be 5 more psi of fuel pressure than there is boost

cruisin down the road with 10 pounds of boost the reg will be creating 15 psi of restriction

my question is - if this pump will flow 100 gph at 14 volts and 15 psi that means that all the fuel in my tank will have been pumped thru the elec pump and the p-pump and some of it thru the injector return more than 3 times in the first hour. close to 8 times in the second hour (because there is less total fuel then) and who knows how many times in the 3rd and 4th hour. isnt the fuel gonna get really warm if not hot by the time i am down to 1/4 tank??????

what do you guys think?

thanks, don
 
I'm to busy trying to figure out why you want your FP to be 5 psi more than boost...
 
Yah, but it will be really clean by a 1/4 tank, LOL.


You aren't gonna have to worry about it heating up, since, about teh only time you are gonna use 20 gallons at one time, will be going down the highway, and heated fuel only hurts fuel mileage, not a p-pump.

You could put a fuel cooler on it. The d-max's come with them factory..

Merrick
 
Semi tractors run fuel coolers for that reason. Just a little radiator.
 
i had ordered a nice tranny cooler to use just for this purpose...on the old truck

musta sent it back to summit as for the life of me cant find it now

i guess i wont worry about getting another one

yet
 
displacedtexan said:
I'm to busy trying to figure out why you want your FP to be 5 psi more than boost...
Click to expand...

to two or too?

or to do?

geez cut me some slack man....least its one way to slow down the superheating problem lol (for the reg to create pressure it makes a restriction)

well, i could just set the thing at 5 psi and leave it there but then like i said, the fuel is gonna be returning at a high rate

or i could set it at 50 all the time but i dont know if the pump (either of em) would like that?

so i figured 5 is fine for idle, if i make a blast (or tow up a hill) the 'fp' will increase with boost, holding pressure in the pump and slowing down return volume a little. then, when i crest the hill and lift (or just lift if i was just makin a blast) the pressure will decrease and volume will increase again cooling down my pump (both of em) (esp the p-7100 and esp if i put a cooler on it)

make any sense or is the theory totally wacked?

dont hold back now...
 
ps - yes i understand that with twins on it it will need a boost elbow in the boost ref port so it dont go over 50 psi (fp)

that it wont want 1:1 then

right now i have it gated to 40 psi so 1:1 should be fine: 5-45
 
Honestly, I read your post and my one track mind immedately focused on why you would regulate it that way. I've never heard of anyone referencing fp off boost.

5 psi isn't enough at idle...
 
Factory service manual says the pump need i think 17-22 psi at idle.

5 psi will not be enough. It will run badly, probably lope and miss if it even runs at all.

Not to mention if you set it to be 5psi more than the boost, and you are driving along at 60mph at 2-4psi with 7-9psi fuel pressure. Not gonna work:badidea:

Set a regulator at a fixed 40psi, and forget it.
 
Cummins Driver said:
Factory service manual says the pump need i think 17-22 psi at idle.

5 psi will not be enough. It will run badly, probably lope and miss if it even runs at all.

Not to mention if you set it to be 5psi more than the boost, and you are driving along at 60mph at 2-4psi with 7-9psi fuel pressure. Not gonna work:badidea:

Set a regulator at a fixed 40psi, and forget it.
Click to expand...



Well in my experience with low fuel pressure i have never once had my truck run any diffrerent..... whether my fuel pressure was at 2psi at WOT (which it has been there:doh:) or if it was at 40psi WOT. Before i made changes to my return valve thats how it was... when i raced or dynoed my fuel pressure would drop to almost 0psi!! but the truck never missed or ran any different.

Jason
 
Set a regulator at a fixed 40psi, and forget it.
Click to expand...

depends on whether or not the 40psi can be maintained under WOT conditions.

Boost referencing fuel pressure is a good idea to maintain pressure and flow through the IP under varying conditions. I personally would set the initial pressure higher than 5psi, but that is just me.

I've never heard of anyone referencing fp off boost.
Click to expand...

I've seen a handful of posts regarding boost-referenced fuel pressure on CompD
 
Either way the P/pump requires 17 to 22 at Idle 38 to 42 during cruise. The return pressure normally is 14 to 15 psi.

Without these numbers all you will do is starve the pump.
 
Cummins Driver said:
Set a regulator at a fixed 40psi, and forget it.
Click to expand...

This is what I would do! In my opinion you need pressure there to get the max amount of fuel into the plungers which also provides lubrication and cooling. Why else would the factory install a relief valve in the return port? Don't take this as gospel it's just my$.02
 
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