Engine/Transmission (1998.5 - 2002) Why Banjo Bolts???

[WadePatton]

my take

And I'm a real greenhorn at this, but:



I've read about 900 pages of this stuff. Seems to me that larger line would be a good idea on the suction side of the LP. It would add to the volume and siphon effect from the tank.



Although I haven't changed my fuel requirements YET, I plan on AN type fittings first and a larger supply line second.



I also expect to see LESS pressure on the guage when the banjos are removed--if indeed they permit freer flow downstream of the LP. As long as I can see SOME pressure on the guage, I'm getting fuel--oh, but am I getting enough .



Feels akin to tail-chasing.

 

[Gary - K7GLD]

"I've read about 900 pages of this stuff. "



MAN, ain't THAT the truth!



One day THIS is the latest updated pump - by the time ya get one, something ELSE is now better... I just wish some smart fella would finally figure out what REALLY gets the job done, no doubt about it, and we could spend MORE time enjoying these trucks, and LESS time with our eyes glued to pressure guages and biting our fingernails...

 

[HVAC]

Pressure

QUOTE:



"I also expect to see LESS pressure on the guage when the banjos are removed"



You will see MORE pressure. You will be releiving a restriction that has been causing your pressure to be as low as zero under load.

 

[Gary - K7GLD]

"You will see MORE pressure. You will be releiving a restriction that has been causing your pressure to be as low as zero under load. "



Depends on WHERE in his system he gets his guage readings!



IF he takes his readings UPSTREAM of the "restriction", then REMOVES that restriction, flow will increase, and pressure will drop to some degree - the same as my example of a water hose above - with a restricted hose, pressure on the SUPPLY side will be high - and flow reduced - but REMOVE the obstruction, and pressure at the same point will DROP, and flow will increase...



IF we claim pressure will increase no matter WHERE the obstruction is removed - it's like saying pressure inside a baloon will INCREASE when you untie the knot holding the air in! In THAT case, we would have a self-inflating baloon!



The only real question - and all this may be quite moot, is in OUR case, are existing restrictions significant enough to even BE a problem to begin with - I haven't a clue - but it's worth considering as part of the overall system upgrades...

 

[HVAC]

I May Be Ahead Of You

He told us where he was getting his readings!!!



QUOTE:



"I also expect to see LESS pressure on the guage when the banjos are removed--if indeed they permit freer flow downstream of the LP. "



LP = Lift Pump!



That means downstream of at least two banjos. When those two banjos are removed in place of -6 fittings the pressure will rise at that point. I have done this test. IMO the only place to measure fuel pressure is at the VP44. At this point the pressure will benefit to a greater extent from the removal of even two more banjos (restrictions) in the filter housing.



QUOTE:



"IF he takes his readings UPSTREAM of the "restriction", then REMOVES that restriction,

flow will increase, and pressure will drop to some degree - the same as my example of a water hose above - with a restricted hose, pressure on the SUPPLY side will be high -and flow reduced - but REMOVE the obstruction, and pressure at the same point will DROP, and flow will increase...



Who have you seen taking pressure readings prior to the lift pump? What would that serve? The restriction has been identified as the banjo fittings in this topic.



Truth is, the pressure prior to the lift pump is negative. If we follow your logic, eliminating the main injection pump (same as eliminating the restriction on the end of the hose in your example) the pressure would rise (not drop) in that the pressure would not go negative to the degree it did with the restriction in place. This does not apply to our situation since the main injection pump remains a constant in all this.



I suggest we contain our discussion to the pressure at the inlet of the VP44 and not convolute the topic.



You WILL see pressure INCREASE at the injection pump as a result of removing restrictions in the system such as the banjos or undersized fuel line.



Sorry to burst your self inflating balloon!:-laf

 

[jerryrigg]

HVAC-



I need to throw this out there... . There is a darn good reason to measure pressure prior to VP44. It is for monitoring your fuel filter!... If you only have a single pressure gauge then yes, mount it on the VP44 as this is the most critical, If you have deep pockets install a 2nd gauge at the inlet to the filter. This is going to give you a true reading of the Lift Pump Pressure. The manual states the inlet pressure to the VP44 should not have more than a 5psi difference. If the drop is more than 5psi time to change your filter. Considering my recent load of bad fuel I am considering adding this 2nd gauge or I am going to get in the habit of hooking BHoppers gauge to the inlet on a regular basis.



-Matt

 

[WadePatton]

the can that I opened

Less pressure with MORE flow. Which would be indicated by lower pressure readings, but less difference in the idle/WFO and maybe even MORE pressure at WFO.



Hydronamically speaking that is.



I'll let you know what really happens.

 

[OutbackDiesel]

All this talk raises a question for me since I have become sensitive to injection pump failure. Has anyone seen or know of a possible failure related to the overflow line becoming restricted? Is that not the return line to the fuel tank? The two thirds of fuel that was mentioned earlier as going through the 44 is used to cool and lubricate it right, then it passes through the overflow back to the tank is that right? Wouldn't there be a problem if that was no longer allowing fuel to cycle as it should?

 

[Gary - K7GLD]

"He told us where he was getting his readings!!!



QUOTE:



"I also expect to see LESS pressure on the guage when the banjos are removed--if indeed they permit freer flow downstream of the LP. "



LP = Lift Pump!



That means downstream of at least two banjos. When those two banjos are removed in place of -6 fittings the pressure will rise at that point. I have done this test. "

======



SURE - because you've just "opened the faucet" more, allowing more FLOW and pressure thru the LP, against the downstream obstructions that are STILL THERE! Naturally, the pressure at that point WILL increase - but if you THEN REMOVE or reduce the remaining downstream obstructions, and assuming there are no other restrictions beyond, pressure will REDUCE to some LOWER value, since there's nothing LEFT to restrict flow! Of course, we know THAT isn't totally possible, since various internal elements of the VP44 ITSELF restrict total LP pressure/flow, regardless of various external fittings used... What we DON'T know, is exactly WHAT the maximum flow rate is possible/recommended directly into the VP44 at, say, 16 psi or so - and WITHOUT knowing that, various efforts to increase flow above stock values are sorta "shots in the dark"!



Tho we HAVE heard vague refferences to 18-22 psi as being limits of internal VP44 seals...





BUT, if all we're REALLY interested in for a "feel-good" sensation with fuel pressure, all we need do is insert a 1/16 inch restriction in the fuel line immediately AFTER the pressure sensor, wherever it's installed - THAT will deliver a reading near the maximum the pump is capable of delivering - AND, most likely, a soon destroyed VP44... OTHER restrictions downstream from the sensor do EXACTLY the SAME THING, just to varying degrees, depending on how severe they are!



====

"IMO the only place to measure fuel pressure is at the VP44. At this point the pressure will benefit to a greater extent from the removal of even two more banjos (restrictions) in the filter housing. "

=====



No doubt... And it is CERTAINLY the most critical point for proper operation and life of the VP44!



MY comments and observations have been directed primarily towards the beginning post in this thread - concerning Banjos used by DC at the VP44 itself:



======

"Does anybody have a clue as to why DC/Cummins/Bosch uses banjo bolts instead of 90deg AN fittings on the VP44??? Is there an advantage to banjos that I am unaware of?? Were they just on sale when the VP44 was designed?? Just curious. "

=======





- tho' we HAVE expanded to various elements elsewhere in the fuel system. I certainly agree that decreasing restrictions PRIOR to the LP will allow its greater performance/efficiency, and presumably, higher resulting pressure.



BUT, whether pressure increases will occur DOWNSTREAM from the LP, at the VP44 itself with larger connectors at that location *only*, I seriously question. And it probably isn't even a critical issue, since expected increased FLOW in itself is benefit enough to justify the change, especially if OTHER system improvements are made as well...



======

"Who have you seen taking pressure readings prior to the lift pump? What would that serve? The restriction has been identified as the banjo fittings in this topic. "

=======



YUP, originally concerning those AT the VP44 itself, as I pointed out above! MY comments regarding pressure relate entirely to to what occurs AFTER/beyond the greatest restriction in the total system - regardless of where the guage sensor is installed! After all, guage pressure at ONE point in the syatem CAN be substantially DIFFERENT at another point, depending on restrictions present along the fuel's path!



I'm not thoroughly familiar with various differences in fuel systems year-by-year in the later trucks - but based on comments and instructions on some fuel pressure installations, THOUGHT it was pretty common practice on some older trucks to install the pressure sensor at the fuel filter - either before or after the element, rather than directly at the VP44 as the latest trucks now do...



In any event, it's for SURE that removing as many restrictions as possible WILL improve fuel flow, and most likely increase overall system PRESSURE as well, if done thoroughly - but increasing only PORTIONS of the system, while leaving significant OTHER restrictions in place SERIOUSLY compromises the other improvements - and THAT has been my intended primary point!



And hey - this is intended as only a DISCUSSION - not a debate or argument!

 

[Gary - K7GLD]

Most of the above could have been avoided by reading the earlier thread "pumps, fuel lines and whatnot":



http://216.235.147.117/forums/showthread.php?s=&threadid=11672&highlight=pumps



It's long, 10 pages - but EXCELLENT reading for those seriously interested in efficient fuel delivery in the 24 valve engines. This one post below from a respected source very well sums it up:



=====



"For the record,



This whole thing for me started when i read the post about prime loc causing lift pump and the vp44 pump failures.



I found the whole post very interesting, and somewhat confusing, and i must confess i cheated while doing some of my r&d. I hired an engineer to check out the system but wanted to verify his findings before commenting.



I'll be honest with you , i thought this could be a good business opportunity, selling a complete fuel system upgrade.



When the engineer gave me his findings, his findings suported prime loc that pressure has very little meaning without flow.



Obviously i have invested a great amount of money to date in this project, i however believed it would be a good investment at the time.



Much to my chagrin, our testing proved the engineer and prime loc's position.



Based on all our findings, the most effective method is to simply move the oem lift pump closer to the tank and clean up some of the fittings(banjo bolts).



Installing a bigger line to feed the existing oem pump or aftermarket high performance pump at its factory location is a waste of money.



There really was no politically correct way of saying this, i know a lot of people have invested a lot of money.



I am not an expert in fuel systems but i have to conclude as long as your pressure does not drop below 2 psi,you will be ok with the oem system as is.



Next upgrade from there in my opinion would be to move the oem pump closer to the tank.



Keep in mind those of you in cold weather climates, the engine compartment does provide a warm location for your fuel pump to protect the fuel pump from geling.



From there a slightly higher flowing fuel pump located closer to the fuel tank, and once again if cold weather is a factor , the engine compartment is a warmer climate area.



Let me know how you feel about our findings, i am a transmission technician and i am trying to learn about the fuel systems just as you are.



Bill Kondolay

Diesel Transmission Technology"

=======



NUFF said!

 

[juicedcummins]

This is a good thread guy's!

I'm a believer in more flow = more constant pressure and have rigged my truck in such a way. I did this before reading Bill's post a few month's back and he makes it sound simple, something I'd have trouble doing.



This is what I have done on a temporary setup.



-removed all banjo's on the supply side and replaced them with a straight barbed fitting. Even this fitting was drilled out for more flow. {I've seen the banjo's that are supposed to be improved but they fall short in my eyes}.



-all fuel supply right to lift pump was replaced with 3/8 rubber fuel line , including the short piece from the filter to the VP44.



-moved lift pump to the rear and added a relay fed with 10 gauge wire.



-aux tank gravity feeds into the tank selector valve but factory tank doesn't.



-there is an aux filter right after the lift pump.



This is what I see:

16+ psi@ idle

16 psi @ 75mph with 2k boat in tow

13psi @ WOT comp on 5/5



This setup has worked flawlessly 15+k. The only trouble was a wild reading on pressures right down to 2psi comp off. This was a few weeks back and it would do it after driving about 100miles. It would do it every time. I stuck in a new overflow valve and a good drink of fuel lubricant and now it works rock solid again. {fiqures-just bought a new lift pump and was about to change it in} I just came back off a 800 mile run with a 2k boat and it worked perfect all the way,so my Lift pump is fine.



There has to be restiction in the banjo's because some off the guy's running a pusher are seeing less pressure than me.



A pusher can be added restriction if the flow rate isn't high enough to properly feed the cummins lift pump. An inline pusher like the Gm's used to use{at least the carter has a fine screen} can plug to add more restiction yet in the system.



A banjo is a change in direction,and that has to be a form of restriction.



I am no expert but this is how I see it.

 

[juicedcummins]

Sorry for the long post guy's.



Don't get me wrong I don't hate pusher systems. I 've ran a pusher system on my 93 6. 5 since new, long before the 24 valve hit the road. Gm has a supply problem that was never noticed.

 

[HVAC]

Nice Job!

JCummins, you are the perfect template for everyone interested in this discussion. Removing the banjos and the 3/16 fuel line netted you more stable fuel pressure at a much greater pressure.



Moving your lift pump back nearer the tank is a great move as well. Well done.



JCummins has reported the same results I came up with two years ago. We get more pressure after removing the restrictive banjos.

 

[Big White Beast]

No one addressed the biggest restriction......

That would be the stock fuel filter set up. It's only rated at 45 GPH. So if you wanted to really increase flow you would have to look at changing the filter set up too.



I think the stock lift pump and lines are sufficient to handle fuel flow for most of our trucks. The only help it really needs is a pusher to overcome having to draw all the way from the tank and up.



When I added my pusher it said to maintain my warrantee on it I had to add a fuel filter prior to the pump. In our stock set-ups the filter is after the pump. One more thing that could lead to the eventual wear and tear on the lift pump.



I didn't put one in as I'm still looking for a good flowing one that will mount in the rear safely. Any ideas out there?



New lift pump and added pusher. Post filter 17 psi @ idle, 15 psi @ WOT. I'll take those numbers. My gauge only reads 16 psi so I'm guessing on the high end. Pre filter it goes way past the top of the scale. I don't think my pressure is raised to any great extent by the one banjo that's after my fuel pressure sender.



Again my opinion is that the set up we have will handle stock to medium modified trucks just fine. Pressure is an easy way to monitor things but a flow meter would be the most accurate. The problem is pump reliability. In it's stock location the lift pump needs help.



Garrett

 

[juicedcummins]

Big White Beast,

I don't know what you are running for a pusher pump{make, model etc,}.

It would be interesting to find out the flow rate of it if you could.

Your model may be a higher flow rate than any of the ones that I have seen. The ones that I have messed with in the past are all around 35gph @ 7psi. I have one in my toolbox that I was going to use as a pusher if it would work. This pump is 13 psi and 38gph still way short of the factory fuel filter. {in line style}

As far as the last little bit of line from the filter housing not being too restrictive or at least the banjo's,you would be suprised.

The 99's at least the line alone is too small. You can see this looking in the banjo out of the filter. {maybe yours is different}.



Please let us here some flow #'s.

PS; This is not a flame I'm just curios.

 

[Gary - K7GLD]

Two things - if you followed the thread I pointed to above you saw that the absolute MAXIMUM flow at the HIGHEST WOT demand was *30 gph!* and THAT was to an engine that was somewhere above stock as I recall - so the need for vast amounts of fuel flow - or pressure - seem somewhat exaggerated as some see them. Personally, based on what I am reading, I'd like to see a good steady 10-15 lbs directly at the VP44 under ALL operating conditions - more than that seems overkill - and LOTS over that MIGHT cause problems with the VP44 internal seals...



Next, the filter in FRONT of an added pusher pump SHOULD go a great ways to protect THAT pump, as well as the stock LP. You CAN spend quite a bit for the added filter up in the larger sizes - what I have for mine is a Purolator F33144 - I have NO idea what its max flow rate is, but have NO doubt it's greater that the 30 gph obviously required by the VP44 at max load. The in/out fittings of that filter have the same pipe thread size as the Carter 4600 pusher pump I am using (which has a claimed flow rate of around 75 gph at 6-8 psi), and looking into the innards, the internal passages remain quite large - UNLIKE the passages of the 4600 itself, which become VERY restricted once past the threads, in spite of the impressive size of the connecting fittings it comes with... Appearances can be deceiving! Of course, just because the filter LOOKS wide open all the way thru doesn't mean internal restrictions don't exist...

 

[juicedcummins]

GARY-KJ6Q,

I agree with your first paragraph in your last post. You said that 10-15 psi at all times should be lots for the VP44.



I've just seen on another post that you plan on adding a pusher.

Did I miss something or are you just doing a little more testing?



Just because a pump says it will deliever 75ghp @ say 6-8psi it will probably fall WAY short. At least that is what I've seen in the past and maybe the pumps are getting bettter but I doubt it. I know this because I have a simular pump on an aux tank for filling with, and it is more like 75ghp with 0psi restriction. It will make the claimed pres of 15 if you restrict it enough but the volume isn't there while restricted. From what I've seen the more restiction you have, the less volume you have @ the end. Pump specs mean very little on a restricted system.



The 30 gph spec for the VP44 is a low end spec. More volume is better as long as the max psi @ the inlet is around 17 psi. More fuel = more cooling capability.



The only restiction that should be on this system is the overflow valve. The factory supply falls way short of 3/8.



Step 1; move lift pump to rear with a relay to supply enough power to factory lift pump.



Step 2: replace all supply lines to a true 3/8 line.



Step 3: get rid of all banjo's and go to a straight barb fitting.



Some of the guy's like the stainless lines etc, but I think it's like putting perfume on a pig! I bought this thing to work and don't do the show and shine thing.



HVAC; has done a simular setup from what I read and we both know it works.



It makes me wonder have many lift pumps have been changed out because the overflow valve was weak or bad? I have seen this a couple of times now , including my own truck.



This is not a flame GARY-KJ6Q. It is good to hear from another that has spent the time trying to work this out,instead of following the others without doing the research on their own.



Again I"m no expert!

 

[WadePatton]

But ain't #2 D a mighty fine perfume for a pig?

 

[illflem]

ideas from a 12 valver

How about the fuel pumps used in the gasser tank modules? Also wonder if high pressure pulses coming back from the VP are causing lift pump problems, is there a check valve in the system?

 

[Big White Beast]

Illflem...

I started a thread a while back regarding the VP44 pulses. There were a few ideas kicked around but nothing seemed to really materialize out of it.



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=49673



Gary and Juiced, I don't take any of this as a slam. It's an open forum to discuss possible problems and solutions. This is how I learn. I did state that it was my opinion and not a fact. The pusher pump I'm using is a carter but packaged by NAPA. Their model # is P4070. Their literature didn't have flow rates or other data. It is a low pressure, 7 PSI, I believe. I went with it on the recomendation of a friend who's been using it for 8 months now with excellent results. Early on I did put on Ray's Banjo's to try and help the stock pump survive. It also gave me a better place to connect my senders to. With DD2's and an EZ I'm sure my flow rate is adeqaute now so if this set up lasts I'm probably done unless someone comes up with a sure fire better way. I will monitor the threads though to see whats up.



Garrett