Please forgive me, but I fail to see the reason you need anything more than a few psi of fuel pressure at the injnection pump inlet. As long as the injection pump isnt pulling a vacuum, it is being delievered more fuel than it needs with the rest being returned to the tank, and yes I understand that helps cool the pump, but the fuel thats flowing through the injection pump to the injectors also cools it. For that matter, the fuel flowing through the pump to the injectors is being heated as a result of that, and will improve atomization and thus combustion. Flowing tons of fuel through the pump and back to the tank will perhaps over-cool the pump, loosing the desireable effect of heating the fuel to be delivered to the injectors.

I have seen all sorts of gimicks and high dollar setups on here for lift pumps, some that deliver 150 GPH to the injection pump and garantee 15 Psi at all times etc etc etc. For the record, 150 GPH is enough for about 3,000 HP continuous.....

Whats wrong with a setup that can still hold 3 to 5 Psi at full power??


Kevin

 

the vp pumps require fuel for lubrication and cooling, and they do seem to do better with a nice steady diet of fuel.

 

not only cools the ip but lubes it to. the hotter the fuel the lower the viscosity the less lube. your turning 15 lbs into (cant remember off hand)??000 lbs, that creates lots of heat. but it boils down to 3-5 not being enough. ask anyone whos lost one most are due to not enough fuel

 

150 GPH rating is usually a full flow rating, not flow at 15 psi, big difference. The obsession is people not wanting to be broke down in the middle of nowhere with a trailer on the back, a ruined vacation or lost sales,etc. if they can prevent it by adding an aux. pump or monitoring fuel pressure. FOREWARNED IS FOREARMED

 

2001 ETH, 96,000 miles so far, with Rv 275's TST PM3, stacked with EZ, for 90,000 miles. I never had anything more than 5 psi at full power or 10 psi at idle. No problems at all with injection pump.

Have a Cummins 'C' emergency generator at the plant. #2 Oil, transfer pump is set to deliever 2 to 4 Psi at all times to the injection pump no more.

As for lubrication, if the injection pump is full of fuel oil and delivering fuel to the injectors, its being lubed period.

I am sorry, I have to respectfuly disagree with the responses so far.


You will notice that in most of my posts, I try to denounce so called 'snake oil' sales gimmicks which I feel fool alot of us into spening $$$$ where they dont need to be spent.

I mean no disrespect at all, just enjoy talking about TECHNICALLY SOUND explanations for stuff, not wives tales or sales gimmicks.


Kevin

 

Think of the VP in a smilar fashoin to your engine.....

Just cause your engine has oil in it doesn't mean it's being lubed.


it needs oil PRESSURE to do it.... A rotary pump like the VP is much the same.

 

Kevin,

You can disagree all you want.. But the facts are that since the inception of the VP44 pump and all the technology around, its a known fact that the fuel pressures you are running are LOW and you are on the lower end of the reliability spectrum. And if you think about it a paltry 2 psi input into the pump would probably be more like -3 at the pump sleeve piston at the time of the injection suction event. CAVITATION??? Maybe not... But definitely not excess fuel for cooling of the inlet to the injector sleeves or swash plate.

Trolling for horror stories about lost injection pumps would take about 100 pages. Do a search here, its nothing new and you are really not re-inventing the wheel here.

Sorry to rant... but the experience here with guys that have been doing Diesel and Diesel performance since 1989 may have a little more merrit... These are the facts and not urban legends here. Sorry to burst your bubble.



IMHO... J-eh

 

Lil, Dog, you dont ever need to apologize for ranting... I am a regular!!! lol.

And actually, now you are making an excellent point indeed...... The pressure at the sleeve at the point of suction is what matters.....Not at the inlet to the pump.. And you are right, if the pressure in the sleeve as the piston draws down goes negative, cavitation, dissolved air precipitation, only to be re-compressed a moment later with ensuing shock....


Thats what I am talking about, logical, TECHNICAL, reasoning behind the things we are doing. You have made me proud Lil Dog. These are the types of discussions I LOVE.. and the reasons I often word questions the way I do.


Kevin

 

Good point Kevin. Most folks don't realize that when any fluid passes though a point of rapid pressure change that air bubbles can form in the fluid.
Almost like the bends that divers experience.

 

So is this to say that I should'nt worry about my fuel presure going from 15lbs at idle to 11lbs at cruise to 4lbs at wot? Should I only be concerned if I see 0 lbs presure? What is causing the dreaded vp failure when guys are seeing low fuel presure but not 0 presure?

 

My pump died with 18psi idle and 12psi at wot. Never had low pressure, yet I tapped the wire for a fuel box and see yah, within 15 seconds of 5x5 wot. I would have too say poor tolerances and perhaps entrained air in this case. Good pump , bad pump? Who knows, but after it nips you for a couple of grand ( towing and all) the possibility of a after market products claim to help remove entrained air (FASS) is worth a try. IMO my pump died because it was either a bad pump or entrained air so hopefully the entraind air wont be a issue now that I have added the FASS. There is no doubt in my mine I would still have the original VP if I had not pierced the wire, but the addition of HP taxes the rest of the entire system. What is ok to keep a stock engine and componants alive doesnt count when its bombed. Just my $.02

 

The air entrained in the fuel system and resulting cavitaion plays a BIG part in killing both the IP and LP's. Thats why the FASS/AIRDOG are the way to go. Not only do they provide LOTS of fuel pressure to cool and lube the IP they also rid the fuel system of air which will help your pumps last a lot longer (even on a bobmed truck). No one likes shelling out that kind of money for a FASS since the fuel system design is the problem - but its just one of the problems with owneing a 24V. Repair the fuel system problems and the 24V is probably as reliable as a 12V.

 

ratsun,

I had the first lp replaced under warranty with about 10k on my truck. The truck was pure stock and never worked hard. No towing, etc. I know your failure was very close to the pierced wire event, but who can so for sure that was the cause, when you consider my failure. I really think on the 02 trucks that the lp used by Dodge just doesn't fit the application well. Some believe it is the lp's location, etc., but I think it was a badly engineered part for this particular diesel application.

My second one seems to be on its way out already. In 2K miles of use it has already dropped 2-3 lbs of pressure at speed. Unbelievable.......

Tom

 

Some of you guys need to re-research the reasons the LP fails on these trucks. It not a bad pump or a poor location. Its all because of the small restrictive fuel lines. Tests have proved that by increasing the fuel lines to 3/8" or 1/2" and getting larger banjo's (or better yet eliminating them) your fuel pressure will increase and greatly extend the life of the LP and VP. There has been tons of talk about this, so it surprises me to read guys saying things that arent true. Yes the FASS is superior but expensive. The stock LP will supply, I believe, around 375 HP.

 

Just to add to what I just said. Some guys, including me, have found their fuel lines between the LP and the VP to be as small as 1/8"!!! And strange thing is there is no consistency with the sizes found.