Safe fuel pressure

[gassernomore]

Ok gang! Going to make this as simple as possible. On another forum everyone is now believing that 5 psi is a good fuel pressure to run. This is being said by a supplier that sells VP pumps. Although the Dodge service manual says 10 psi is the minimum. I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?

[ISX]

Keep it in the green! 10psi min!

Edited January 14, 2010 by ISX

[IW378]

I'm a newb to this stuff but from what I have gathered above 10 is good. With my stock pump and filter my pressure was at around 12 at idle and dropped to less than 10 under a good load. I feel more comfortable with my new setup. Idle at above 15 and about 14 under load.

[Mopar1973Man]

Yeah ISX is cheating and pulling my photoshop pic... But I agree I would keep it in the green... :thumbsup:

[ISX]

Yeah ISX is cheating and pulling my photoshop pic... But I agree I would keep it in the green... :thumbsup:

What do you expect, you keep playing with things, giving me all this time to take credit for your work You would think all pictures from that part of the site would bear the Mopar1973Man logo at the bottom, like all my album pictures

[flman]

Ok gang! Going to make this as simple as possible. On another forum everyone is now believing that 5 psi is a good fuel pressure to run. This is being said by a supplier that sells VP pumps. Although the Dodge service manual says 10 psi is the minimum. I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?

Is that the Northeastern supplier by any chance?

[gassernomore]

Is that the Northeastern supplier by any chance?

That is not the one that I am aware of.

[flman]

I have recently had correspondence with Cummins on this topic and they say "10 psi is the minimum" for the engine. I want you all to know I run 17 psi and am HAPPY with this pressure. What do you feel is the proper pressure to run?

Kind of funny Cummins wants you to have 10+ PSI, and then they supply the engine with a POS pump? Edited January 17, 2010 by flman

[ISX]

I'll bet they had a good one on it and dodge told them their mechanics needed something to work on so they put that one on it instead Just like the silencer ring and various emissions things....

[Mopar1973Man]

Kind of funny Cummins wants you to have 10+ PSI, and then the supply the engine with a POS pump?

Actually it like all thing on the market Cummins and Dodge both bid for manufacture that are the cheapest to supply part and Federal Mogul (Carter) happen to be the lowest bid at the time. They most like test drove the truck for a short time and was happy with it and then it hit the market... Like a lot of people are quoting Blue Chip for 5 PSI is more than enough fuel for the VP44... Yeah sure that when you take a new pump put in on the test stand for a few hours and disassemble the pump. Nope no wear must be ok... Now try that on a VP44 mounted in a truck and put it through its paces for 700K to 1 million miles I doubt it will barely make 50K miles and puke like mine did...

[LiveOak]

I am going to have to disagree with the poll and the premise of the question it poses. 10 psi, is the ragged, rock bottom, unsatisfactory minimum to get by. The VP-44 can fuction adequate with this inadequate fuel pressure the the fuel return valve is not going to open allowing any excess fuel to return to the tank and thus aid in the absolutely essential task of cooling the VP-44. In my opinion, 15 psi is the minimum adequate fuel pressure. This not only provides full fuel for engine operation but also provides adequate cooling and lubrication of the injector pump.

[Mopar1973Man]

I am going to have to disagree with the poll and the premise of the question it poses. 10 psi, is the ragged, rock bottom, unsatisfactory minimum to get by. The VP-44 can fuction adequate with this inadequate fuel pressure the the fuel return valve is not going to open allowing any excess fuel to return to the tank and thus aid in the absolutely essential task of cooling the VP-44. In my opinion, 15 psi is the minimum adequate fuel pressure. This not only provides full fuel for engine operation but also provides adequate cooling and lubrication of the injector pump.

Very well put... But is true... 15 PSI will crakc open the overflow valve and allow the fuel to flow on the return side and aid in cooling...

[gassernomore]

I am going to have to disagree with the poll and the premise of the question it poses. 10 psi, is the ragged, rock bottom, unsatisfactory minimum to get by. The VP-44 can fuction adequate with this inadequate fuel pressure the the fuel return valve is not going to open allowing any excess fuel to return to the tank and thus aid in the absolutely essential task of cooling the VP-44. In my opinion, 15 psi is the minimum adequate fuel pressure. This not only provides full fuel for engine operation but also provides adequate cooling and lubrication of the injector pump.

Everything you say I would have to agree on. I could have worded it differently. My whole point of writing the post was that someone else other than the manufacturer of the engine was saying that Cummins was wrong and that the correct pressure was lower than what was recommended. I believe everyone on this forum is running above 15 and below 20 psi because they understand the operation of the pump and when the return valve opens. Thanks for clarification on my post! It would be like me saying that Mike is wrong in the way he "counts what is a post on his forum!"

[Mopar1973Man]

It would be like me saying that Mike is wrong in the way he "counts what is a post on his forum!"

Just got to pick on me don't you... But...

I believe everyone on this forum is running above 15 and below 20 psi because they understand the operation of the pump and when the return valve opens.

I feel the same way I rather crack open the overflow valve slightly and have just a bit more pressure feeding the pump without being excessive. Edited January 24, 2010 by Mopar1973Man

[jlwelding]

Like I posted before 17k and on my 4th vp44. If it wasnt a cummins I would have trashed this truck a long time ago. I think I round trip my last one in 3 hours.

[Hood Latch]

Question: The guy up in the northeast that sells the rebuilt vp44's and is saying that you have adequate needs with 5p.s.i., how long is the warranty on his rebuilt pumps? I guess I am wondering why he would say 5 p.s.i. is sufficent, if he is going to warranty his vp44's, after telling us that 5 p.s.i. is enough. Or, am I missing something here ? Seriously, not trying to be sarcastic.

[Mopar1973Man]

In the same breathe he says "5 PSI is enough", but Bosch turns around and says " That diaphram damage is caused from low fuel pressure". Then your 5 PSI buddy mentions that if there is a "diaphram rupture" no one will warranty the pump!So is it worth the risk? (Personally No.)Has our 5 PSI buddy done any long testing of this? 100K, 200K, or 500K miles? (None documented as of yet!)

[guesswho512]

this is off http://www.bluechipdiesel.com/fassinfo.html i bolded what i thought is important

Blue Chip Diesel Performance proved in 1999 that 5 PSI, under load, made all the horsepower the VP44 pump could make, even with stock fuel lines, fittings and supply pump. We did this test on a dyno when we were testing our Fuel Management System. We thought the amount of return fuel flow at this pressure was adequate for internal lubrication. This proved to be all good information as it turned out, just not enough information. We didn’t know then what we do now, namely that of the heat issue, so we never measured the temperature of the return fuel under a variety of operating conditions.

and earlier:

This is from listening to all of you in the “Real World” and testing the accuracy of my diagnostic procedures daily. I am convinced that HEAT IS THE KILLLER OF THESE PUMPS, based on information I have learned over the years. I got this information by listening to all the great people who call me for technical help, and keeping track of initial as well as repeat failures.

ohh...notice he doesn't say what load %? i mean exhaust brake and 3 cylinder idle = 33% load. mind you at idle!

Edited January 24, 2010 by guesswho512
the last part

[Mopar1973Man]

this is off http://www.bluechipdiesel.com/fassinfo.html i bolded what i thought is important

Blue Chip Diesel Performance proved in 1999 that 5 PSI, under load, made all the horsepower the VP44 pump could make, even with stock fuel lines, fittings and supply pump. We did this test on a dyno when we were testing our Fuel Management System. We thought the amount of return fuel flow at this pressure was adequate for internal lubrication. This proved to be all good information as it turned out, just not enough information. We didn’t know then what we do now, namely that of the heat issue, so we never measured the temperature of the return fuel under a variety of operating conditions.

Ah Ha... Here is the kicker... There is no return from the VP44 if the pressure is at 5 PSI... The overflow valve doesn't open till 14 PSi... So how can there be return fuel??? Also never mention the suppling pumps GPH rating??? (Stock, AD 100, FASS 95??) Another thing how long was it on the dyno 2-3 minutes? 1 hour? 10 miles?

and earlier:

This is from listening to all of you in the “Real World” and testing the accuracy of my diagnostic procedures daily. I am convinced that HEAT IS THE KILLLER OF THESE PUMPS, based on information I have learned over the years. I got this information by listening to all the great people who call me for technical help, and keeping track of initial as well as repeat failures.

As for heat failures then you would see more pumps failing in the south and not the north... Fairly common even up here in Idaho to see VP44 fail... I don't think its all about heat though... I might be a factor but not the main one... Maybe the heat factor is from the fact the overflow is completely closed and there is NO extra fuel for cooling and the return fuel is coming from the injectors bleeding off.

ohh...notice he doesn't say what load %? i mean exhaust brake and 3 cylinder idle = 33% load. mind you at idle!

I added my tidbit again... Because as for BC post is rather general and doesn't give important information... The only number he gives is the 5 PSI number... So what I can place my truck on a dyno and product max power at 5 PSI... But there is nothing said about max lifespan... Remember if he told the truth about that then he'd be out of a job... Edited January 24, 2010 by Mopar1973Man

[flman]

Not to defend him or nothing, but he does recommend the Fass DDRP for longer life. Sure the VP44 will run with no lift pump pressure at all, my original VP44 did it a bunch of times, and I did not know it, till I got hesitation, or I could not prime the fuel filter, but that does not make it good. Maybe I should send him a link to this site and let him read this thread, that is bad information to tell your customers, he could at least put a disclaimer?WARNING, DO NOT DO THIS TO YOU VP44, THIS WAS ONLY A TEST, IT WILL VOID YOUR WARRANTY!!!!!Actually, they did that back in 1999 when the VP44 was in its infancy, but it should still not be presented on his web page, I agree.

Edited January 24, 2010 by flman
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