P7100 Lube and Heat ????'s

[biggy238]

Would there be any drawback to doing away with the return line on the P7100 and just running just regulated input pressure?

I know the current setup is relying on the fuel flow to the tank to lubricate and cool the injection pump. Let me know what you think.



Kyle

 

[Joe G.]

The P7100 is lubed by engine oil. The fuel system supplies why more fuel than you can burn so it's best to leave the overflow valve and return line in the system.

 

[DieselDoghouse]

What Joe G pointed out is why our setups are often called the 'million mile' engines. P7100's don't fail when fuel flow is disrupted 'cause their oil-lubed. Also, if you restricted fuel return, would that eventually toast the lift pump???

 

[nickleinonen]

the bottom end of the inline pumps are lube oil lubed/cooled. the top end is fuel oil lubed/cooled. . flow through will keep the top end of the pump cooler. .

 

[biggy238]

the bottom end of the inline pumps are lube oil lubed/cooled. the top end is fuel oil lubed/cooled. . flow through will keep the top end of the pump cooler. .

Thank you for stating that before I got to it.



Also, i'm not planning on keeping the lift pump If I go to this setup.



However, Most regulators I've seen have return lines, it would be physically possible to use the stock lift pump and regulate what passes through the return line, by doing away with the overflow valve and plumbing a regulator in the return flow.



That's not what I want to do though. I don't like fuel capacity being tied to engine RPM.

 

[Forrest Nearing]

just ditch the overflow and put a regulator on the return... your pressure gauge will just be on the other side of the regulator vs. a traditional gas application

 

[biggy238]

Are you always so stern when you reply? LOL





Pressure Gauge? Pressure is equal and constant in all directions in a system. I should be able to leave it tapped into the pump banjo like I arleady have it shouldn't I?

 

[Forrest Nearing]

I'm never stern unless I'm being insulted! even then I usually deserve it



I guess my thinking is it'd be easier to just leave the feed side as-is, ditch the overflow and regulate the return line... you could put the regulator anywhere.



I guess it's 6 of one and 1/2 dozen of the other

 

[Joe G.]

I don't like fuel capacity being tied to engine RPM.

Why? I think that is an advantage.

 

[biggy238]

Mostly just because i'm not satisfied with the way mine acts. I'm 90% certain that I've developed a hole in my pickup and i'm tired of dealing with the fuel pressure running between 5 and 45 psi whenever it feels the need to do so. I want some consistancy and I want something that will support fuel mods that may arise in the future. My fuel pressure will maintain 20-30 psi with more that 1/4 tank. Less than 1/4 of a tank and my pressure drops roughly 10psi.



I'm not to the point of building anything yet, but the bed has to come off for the body to be fixed in march so it would be nice to have the ability to go ahead and change what I need to change. I was looking at doing what Ben has posted in the competition forum with the A1000 and regulator but i'm not sure what lines I want to run to and from the pump.



I'm still completely up in the air on all of it.





Would the pulsating of the stock lift pump affect a fuel pressure reg adversely?

 

[Forrest Nearing]

I guess I didn't thoroughly read your post...



I wouldn't mess with polishing up the stock lift pump setup... it actually works quite well... if you were at all concerned w/ pressure dropping, I'd put an inline electric pump between the tank and the lift pump, but that wouldn't fix your low pressure problem below 1/4 tank.



eventually I plan to ditch the entire factory assembly from the tank to the IP and back... I'll just run a FASS to the IP and a regulator on the return line... ditch all that hard line stuff!!!



but for now, the factory setup is working great. I'm kindof affraid to put a pressure gauge on there and see how hard the P7100 is having to suck!

 

[Joe G.]

Biggie,



If you are getting that kind of fuel pressures at low fuel levels only then you have a problem in the tank. The lift pump doesn't do well trying to pump air.

 

[biggy238]

Joe, That's the conclusion I arrived at. It's just not consistant. I think maybe fuel temp and viscosity is throwing me a little bit, But the conclusion is the same, it's an air leak in the tank.



I'm just tired of patching a system that's erroding and i'm exploring my options and i'd really like to build my own system. I'm planning on going to a flooded suction system instead of suction lift.

 

[Joe G.]

My fuel system is in great shape and has been for quite a while. The lift pump is the original. The original OF valve gave up last year so I replaced it with one from TST. The fuel heater is in the trash. The fuel hoses are from LarryB with about 150K on them. I have 30 PSI at idle. 244K miles on the truck. Mid 30s to 40 or better on the road. I don't see anything doing any better for a P7100 pump. No patching required. I really doubt that any fuel system that depends on something electrically driven is going to be as reliable now that I have good hoses and no fuel heater.

 

[biggy238]

Well, I wish I could say the same for mine, but between the mileage put on my truck by it's previous owners, and what amount i've abused it, it's just showing it's age.



It's healthy enough to last a goodly while just like it is. I'm somewhat curious if maybe having a digital gauge with 1/2 second refresh rate might be objectifying the pressure drop, when maybe a mechanical gauge doesn't show that instantaneous pressure drop. I can still pull the pressure from 40 psi to 7 or 9 after about two seconds of WOT in 3rd or 4th gear.



Air leak

Air Leak

Air Leak



I know.