Help....Know just enough to be dangerous and having problems

[Buzzinhalfdozen]

Correct the VP 44 is cooled by fuel and the electronics are attached to the VP44 at the top regardless of how you see it heat rises so the computer is vulnerable. Keeping the overflow valve open on the VP44 with 14 PSI of pressure helps remove the heat but when your 150GPH pump cycles the fuel in the tank at a rate of 32 gallons every 12.8 mins the fuel at lower tank levels never sits long enough in the tank to cool off. Once at half a tank of diesel the pump can cycle 16 gallons in 6.4 mins this is where I have noticed temps to pick up. At a quarter tank(8 gallons) the lift pump will cycle the tank every 3 mins temps climb even further. This is why I brought up a cooler. If the VP44 case is even 10-20 degrees cooler this will help overall component longevity from the mechanical internals, to the electronics package bolted to and above the VP44. Fuel cooling is not the end all fix all but the big 3 have begun adding coolers to help alleviate this problem which is even worse for them due to HPCR systems pushing 21-29 KSI and line velocities even higher than 20 FPS.

Another thing to consider is fuel return on the head is always hot and near engine coolant temp which over time heats up the fuel in the tank.

Something else to consider. The only way to get your pump to move 150gph, or 32 gallons in 12.8 minutes, would be to run a 1/2" line straight from the discharge side of the pump back to the tank. There's no way it can circulate that much fuel through the small hole in the overflow valve. This is where we get pressure from. Now I haven't pulled the return line off to see how much it will flow but I bet it isn't 2.5 gallons per minute.

[Mopar1973Man]

Something else to consider. The only way to get your pump to move 150gph, or 32 gallons in 12.8 minutes, would be to run a 1/2" line straight from the discharge side of the pump back to the tank. There's no way it can circulate that much fuel through the small hole in the overflow valve. This is where we get pressure from. Now I haven't pulled the return line off to see how much it will flow but I bet it isn't 2.5 gallons per minute.

 

Agreed...

 

That won't change a thing being the port from the VP44 is very small so increasing the line size does absolutely nothing. Return port is on the left... I did a video long ago and the return flow rate does not improve with pressure. Only once it reaches 14 PSI its fairly steady from that point on.

[Buzzinhalfdozen]

Agreed...

That won't change a thing being the port from the VP44 is very small so increasing the line size does absolutely nothing. Return port is on the left... I did a video long ago and the return flow rate does not improve with pressure. Only once it reaches 14 PSI its fairly steady from that point on.

My point exactly. You would need a whole lot of pressure to get that little hole to return 150gph.

[Mopar1973Man]

My point exactly. You would need a whole lot of pressure to get that little hole to return 150gph.

 

Problem is the front seal will fail long before you reach that.

 

This is why I don't look at fuel temp or flow issues. Again why do people like me go through extremes both hot and cold and now got 11 years of summers (117*F max this year) and winters (-25*F last winter) no issues.

[Buzzinhalfdozen]

Problem is the front seal will fail long before you reach that.

This is why I don't look at fuel temp or flow issues. Again why do people like me go through extremes both hot and cold and now got 11 years of summers (117*F max this year) and winters (-25*F last winter) no issues.

Well it's possible that other things besides under hood temps are killing them....

[Mopar1973Man]

Back to my original comment about AC noise creating heat with in the circuits.   

 

http://forum.mopar1973man.com/index.php?/topic/10383-helpknow-just-enough-to-be-dangerous-and-having-problems/#entry117004

[Vais01]

My point exactly. You would need a whole lot of pressure to get that little hole to return 150gph.

Pressure is set for us 14 PSI through the over flow valve(also a pressure safety device) but it is not pressure that moves the fuel through the orifice it is flow. Flow is speed, pressure is the result of doing work (also flow restrictions). Fluid velocity is near 110 FPS when the fuel pushes through the .150" orifice which will create a tremendous amount of heat. 

Then the next thing blows peoples minds the sudden reduction of fluid velocity actually begins cooling due to expansion(in the case of fluid the sudden reduction of fluid velocity). The banjo fitting is hot along with the case near the outlet for the overflow valve threads into but the hose will show temperature reduction within 3 inches of the banjo fitting. The whole time flow has not changed it will still be constant 2.5 GPM but fluid velocity will be reduced down to 3 FPS if your return line is .5 internal diameter or near 8 FPS if your return line is .375 internal diameter. 

Hydraulic principles...Not going to say what other neat things I have also learned over the years.   

Edited September 6, 2015 by Vais01

[Mopar1973Man]

Same principal as air conditioning there is high pressure on one side of the orifice and then the pressure is reduced on the other side and you get cold. But the problem is the pressure side will remain hot which is the VP44 its the return line that is getting cooler. The thing is if you install a fuel cooler I would do it on the return line which is the hottest fuel from the engine (injector return and VP44). At least then it would cool the fuel tank. The big problem is being able to disable the cooler come winter time. It would sure suck to have a cooler that helps gell up your fuel tank.

[Buzzinhalfdozen]

I also have a pretty good understanding of fluid dynamics.

Flow is speed. Yes but I can have a 24" pipe at 10,000gpm then choke it down to .150 and then what is your flow and speed. Yes this will will create a lot of heat due to friction but it's still not flowing 10,000gpm.

[Vais01]

I also have a pretty good understanding of fluid dynamics.

Flow is speed. Yes but I can have a 24" pipe at 10,000gpm then choke it down to .150 and then what is your flow and speed. Yes this will will create a lot of heat due to friction but it's still not flowing 10,000gpm.

This is true but not many understand flow and chokes(variable/fixed orifice restrictions). There is a very minor nearly non-existent change in our case due to volume and line differences. The gerotor pump is a positive displacement pump that has a percentage of loss under a specific amount of pressure. Also an additional little bit of loss through the filters and fittings.

 

Fluids are non-compressible and that key means 2.5 GPM must find its way somewhere or something will fail. 

 

In your example 10,000GPM will either wipe out the .150" orifice or create an extreme amount of heat through the orifice then as the fluid passes through the opposite side velocity will be reduced. You never mentioned if that was from a free flowing well or pumped. 

[Mopar1973Man]

OMG...

[Vais01]

OMG...

Hey we can all get a laugh.

[recondoc]

I finally found a video that covers it all.

[dave110]

I would love to have that bumper!!!!

[Vais01]

I would love to have that bumper!!!!

Looks like my Ranch Hand bull nose.

[Vais01]

I finally found a video that covers it all.

Doc I would go this route if I could keep the check engine light off.

[Mopar1973Man]

I think the video is funny...     But I really hate the idea of pushing the p7100 as a fix to every single problem.

 

I think P7100 has it place in the world but not everyone needs to convert to a P-pumped 24V to make his truck run. I've got another gent that contacted me that is attempting this and made more problems than he's curing. Try to cut corners and fab everything at home. When he told me he converted for $250 bucks I knew it wasn't done right.

 

Remember there is guys like myself I'm at 201k on the VP44 pump then 251k on the truck and its 11 years old now and still going strong.

[Vais01]

I think the video is funny... But I really hate the idea of pushing the p7100 as a fix to every single problem.

I think P7100 has it place in the world but not everyone needs to convert to a P-pumped 24V to make his truck run. I've got another gent that contacted me that is attempting this and made more problems than he's curing. Try to cut corners and fab everything at home. When he told me he converted for $250 bucks I knew it wasn't done right.

Remember there is guys like myself I'm at 201k on the VP44 pump then 251k on the truck and its 11 years old now and still going strong.

I agree the P7100 is great if done right but as you said it has to be done right. This is not cheap and is a chore to do.

A well built and we'll fed VP44 will last for a long time.

Edited September 7, 2015 by Vais01

[dripley]

I think the video is funny...     But I really hate the idea of pushing the p7100 as a fix to every single problem.

 

I think P7100 has it place in the world but not everyone needs to convert to a P-pumped 24V to make his truck run. I've got another gent that contacted me that is attempting this and made more problems than he's curing. Try to cut corners and fab everything at home. When he told me he converted for $250 bucks I knew it wasn't done right.

 

Remember there is guys like myself I'm at 201k on the VP44 pump then 251k on the truck and its 11 years old now and still going strong.

 i have 130k on my current pump and 350k on the clock, but mine will be 14 years old next month. My first pump went at 75k under warranty all on the oe lift pump. The second one went 145k with the oe lift pump and its failure and then to the in tank pump where I started having problems with it. The current one has been on an AD and 2 stroke all of its life. Did not know much about fuel pressure until shortly before joining this forum. I have high expectations out of this one.

[pepsi71ocean]

You are correct and also incorrect. A properly sized cooler can drop the temperature up to 20 degrees this is sufficient for the end goal. The issue is velocity through the cooler must be very low and must remain in the cooler for enough time to properly remove the heat.

It is possible but the cooler line size would be fairly large nearing 1 inch. This becomes cost prohibited and may consume too much space. A stacked plate cooler will work but again size can be an issue.

I understand what you are saying, but what I was saying is to attach a cooler to the top of the fcm and think that you will get enough of a temperature drop in an engine room already at 200f.

I don't think it could be done.