Engine/Transmission (1998.5 - 2002) Vp-44

[MikeR]

I don’t see how excess pressure and fuel would cause damage, especially with the pressure regulator and fuel flow back.

If you have ever taken apart a VP44 for yourself, then you'll see the chamber where the fuel first enters the VP44. The hole that the fuel flows into is very small... cavitation seem evident. I cannot see the need to get 20psi + to try and p*ss through this little hole.

I looked at that a long time ago and this is why I will not run a 2-pump system.

 

[EricBu12]

The guy said there was areas of the drive crank or whatever that could become of all things, bent or out of line... ... I didn't get all of the exact wording but bacically, the inlet area, if you have too much preassure, the 14# pop-off works and does return fuel to the tank but too much damages the pump prematurely. More is not better he said. be in spec of 0 or 2 psi to 11-12 psi and it wil work great for a long time. the cooling of the pump is done by the fuel but the fuel reaches max. temp even idleing or light cruise. if hauling, it gets warmer like engine oil under load, well the same is true on the cooling of the VP-44. I admit you will get better cooling if you have like 10 psi rather than having the pump pull the fuel by itself but it reaches max cooling ability in the spec range.



Steve, I would suggest you put a regulator to limit the PSI right away. I told him some guys have 20 psi or more and he said that is hurting the pump. I would think he knows more than us.....

Anyway, my concerns are aleaved, I have good PSI. On to other things, Like mudflaps and stuff

 

[Diesel Freak]

This coincides with what I have been saying all along.



The Bypass valve is not a regulator, but a relief, and the fuel it sends back to the tank does not go through the VP44 rotating assembly.



Two pumps with over 14 PSI to the VP44 is overkill, and unnecessary..... not to mention a waste of money. Just relocate the OEM pump to above the rear cross member that supports the transfer case ( if you own a 4x4, or a similar location if you have a 4x2) it is a tight fit, but it will miss the front driveshaft.



don't forget to add a pressure gauge so you know when the pump is going to take a crap... ... even the aftermarket replacements will eventually fail.

 

[RADdodge]

Hey Eric – are you using a regulator or just one pump? If you’re using a regulator, what kind are you using? As for mud flaps, I just installed some on my truck. Check it out.



https://www.turbodieselregister.com/user_gallery/sizeimage.php?&photoid=1901&width=1

 

[Diesel Freak]

Originally posted by Herman8r

I have just joined the elite bomber club!! And then my injection started to go bad. I have been informed by the dealer that the vp-44 failed due to pressure loss but will not replace it citing TSB 14 002 02--"DC will not warrant the pump due to the splice in the wire harness that Banks spliced into". I called Banks and the tech tells me to take DC to court!! SURE !! I do realize that I am responsible for my actions In reserching places to purchase new VP-44 pumps I found a Certified Bosch Dealer that sells NEW VP-44 with the latest upgrades for under $1200. 00 (Berge's Sales & Service--626-334-0288--Azusa, Ca) I found this at the Bosch web site-www.boschservice.com.



I have not purchased this yet but it is only a matter of time before the pump goes--hopfully not while I'm on vacation.



I am in the search for mechanical fuel pressure gauges. Any suggestion?



Herman8R

To answer your question. I have an Autometer mechanical Gauge with Isolator. I purchaced it through Summit. The rest of my fuel system consists of Aeroquip socketless hose and -6 AN fittings replacing the OEM Banjo fittings. The OE Lift pump has been relocated to the location mentioned in my previous post.

Fuel pressures are as follows.

14 psi at idle

12. 5-13 psi 70 MPH cruise in 6th

9 psi WOT



The only thing I have done to affect VP44 duty cycle, and hence pressure at the VP44 suction is the addition of the Power Puck. Adding high flow injectors do not affect VP44 duty cycle, and therefore do not affect the pressure at the VP44 suction.

 

[Huff N Puff]

A test you can run without a pressure gauge

A very effective way to test a fuel delivery system,is to test volume as well as pressure,we all focus on pressure,and forget about volume. We forget that the pressure we're reading may include air in the fuel . If the lift pump draws air into it 15lbs of erated fuel into the vp44 would shut it down quick or a little air would create a hard start. A quick way is to disconnect the in coming line into the VP44 put it into a quart size bottle,then turn on the key dont start it, should at least pump a pint in 15 sec. It should be solid and steady. If the stream is erated look for an air leak,I'm not certain about this but I think there is a shut off pressure switch, I havn't seen it,think its in the VP44 . Doing a filter change once,I was able to prime the system by leaving the key on,it steady kept pumping. Another way of looking for air is to install a clear line between the lift pump and the VP44. you'll see air bubbles in the line if air is present. Remember try simple and cheap before we settle for expensive and complicated. Hope this helps, Merv.

 

[15w40]

EricBu12 writes, “I asked him (an Engineer from Bosch) what was the operating parameters of the vp-44 and he had to try to convert bars to PSI but he said -2psi to 12 PSI max when running. ”



DC says the lift pump pressure should be 10 psi or more at idle and no lower than 8 psi at full load.



It seems to me that the folks here on the TDR forums (including me) have assumed that the lift pump specifications should be applied to the VP44. You know what they say when you assume something? It makes an “a$$” out of “u” and “me”.

 

[Herman8r]

I AM SOOO CONFUSED!!!

 

[15w40]

Put yourself in the place of DC, trying to deal with the many complaints about the lift pump. When a customer thinks his or her pump is bad, how do you get the hundreds of diesel technicians at the dealerships to test a questionable pump? Measuring volume is not very easy but tapping into a port to measure pressure is easy and cheap. My guess is that DC has determined a good lift pump should make more than 10 psi at idle and more than 8 psi under load. These numbers are greater than necessary to keep the VP44 happy but are used to insure the lift pump can continue to operate for a while (maybe until the warrantee runs out. ). I just hope that the Bosch engineer is not shooting from the hip when he gave out the pressure numbers.

 

[Herman8r]

I am going to the local Bosch dealer next week. They will test the lift pump & injector pump. Then I hopefully will have the answers.



Thanks to everyone for the input.



Herman

 

[work2muchplay2little]

Originally posted by Herman8r

I am going to the local Bosch dealer next week. They will test the lift pump & injector pump. Then I hopefully will have the answers.



Thanks to everyone for the input.



Herman

While you're there... ... see if you can nail them down about what are optimal lift pump pressures, what is too much and why, and what is the best way to measure them. Thanks.

 

[EricBu12]

DC..... is not BOSCH! they did not make it... ... . they say the PSI #'s to Cover their A$$ Bosch made the pump, they know the #'s... . they know what it does... I would rather believe the person or rep that MADE the item rather than the person that sells it. Wouldn't you??

 

[Gary - K7GLD]

Eric sez:





"More is not better he said. be in spec of 0 or 2 psi to 11-12 psi and it wil work great for a long time. "



THEN asks:



"I would rather believe the person or rep that MADE the item rather than the person that sells it. Wouldn't you??"





Perhaps - at least UNLESS the spec the "expert" dictates is pretty much the SAME as what MANY of the VP44's are currently FAILING at - and what the "expert" now claims is "excessive" is what they are now SURVIVING at...





Is it remotely possible that if you asked that question from 10 different "Bosch experts", ya MIGHT get 10 different answers?

 

[Pit Bull]

The more I read and learn about the VP44 the more I am confused. This VP44 is starting to remind me of religion :-{}

 

[A Johnson]

I have heard that other engines use the VP-44, mostly in Europe.



It would be interesting to find out what their specs are for inlet pressure/restriction. And if they are having a lot of VP failures.



Wasn't there a fellow on here that said one of the John Deere engines is using it? Maybe he will report in with the inlet pressure spec for JD.



Some time ago I tried to find this out by searching the net but really didn't have much luck , maybe I will try again. I will report back if I find anything. A Johnson

 

[BK]

maybe we have apples and oranges here...



we have our trucks:

With the vp44 a long way away and very much up hill from the fuel tank. And a pusher pump a long way away which causes cavitation problems in the pusher pump itself and probably failures in the pusher pump.

If the pusher pump is seeing cavitation. . might the fuel going into the vp44 also be aerated? causing earlier failures in the vp44 too?

when the pusher pump fails (low inlet pressure). . it will cause added restriction and make the fact that the vp44 is higher than the fuel tank and a long way away even more of a problem.



the applications and pusher pump specs the Bosch engineers are speaking of may be from different applications...

the rest of the world generally puts the electric fuel pump into the fuel tank for the least lift problems and best cooling. . (ours is bolted to the side of a hot engine). In machine applications , as I've read on TDR board. . the tank that feeds the vp44 is higher than the vp44.



I can see how too high of a pressure through a small inlet hole (cant spell orifice,, - but the spell checker did -) could cause "cavitation" in the fuel going into the vp44's pump section... the increased surface tension caused by the increased pressure would cause more turbulence at the orifice.



I agree with the comment made earlier about DC coming up with some numbers to qualify and bad pump from a good pump.

Pressure numbers , normalized around a given system will be an indicator of volume.



just my thoughts on something I'm learning about here...

I'm down one lp already. . here's hoping the 1. 5-3psi I saw at WOT didnt hurt the VP44

 

[Big White Beast]

Inlet size......

A certain diameter orifice will flow only so much volume. When that number is reached you start to get back pressure at the inlet. In theory anyway. Are we really flowing more fuel or just reading the back pressure because the pumped fuel has no where to go? What is the max flow rate through the VP? If the VP-44 relief valve opens at 14 psi why are we seeing higher numbers? Is it because we've reached max fuel flow anyway? If this is the case how could you possibly due any damage as you've already achieved max flow?



I'd have to agree that there have been more posts of pumps failing due to low pressure than high. As a matter of fact I've never read of one failing due to high pressure.



In the ultimate VP thread Marco lists a few european cars using th VP. There are slight differences as these cars have smaller motors, less cylinders, smaller bore and therefore less demand. There are also differences between the ETC & ETH pumps. Would the same pressures apply? Not that I doubt the Bosch rep, aw heck, yeah I do! I've spoken to many reps that are full of book info and have very little practical field info to give. Was his math correct in translating Bar to PSI? Were these numbers for our VP or the european cars? As they have more than one model out it seems there could also be different numbers available for each.



Don't know anything for sure. Just trying to use a little logic and see what the combined minds of the TDR can come up with. Can this thread be blended into the ultimate thread. Lots of good info thats being left out of that one.



Garrett

 

[Pit Bull]

Re: Inlet size......

Originally posted by Big White Beast

A certain diameter orifice will flow only so much volume. When that number is reached you start to get back pressure at the inlet. In theory anyway. Are we really flowing more fuel or just reading the back pressure because the pumped fuel has no where to go?



Garrett

Garrett, there was a thread that Bill K and some others discussed this issue of flow rate. I think you are right, flow rate is the important factor. I think a dead lift pump and to much demand for fuel from the VP44 equals a dead VP44, I also think that to much pressure from a lift pump/pusher pump means reduced flow rate to the VP44 and equals a dead VP44. The answer to this problem is maintaining the correct fuel flow rate to the VP44 to handle the engines demand. Now I don't know how you do that , but I think we have a lot of bright people here that will figure it out.

 

[Steve St.Laurent]

I also think that to much pressure from a lift pump/pusher pump means reduced flow rate to the VP44 and equals a dead VP44.

Pit Bull, I think you are confused when it comes to flow rate and pressure. On a given run of lines (like the lines between the lift pump and VP44 for example) if you have higher pressure you have higher flow. For example, say you had a stock line setup and were seeing 10 psi at the inlet of the VP44, now you put a pusher pump on and are seeing 20 psi - you have more fuel running into that pump. Now say you kept the stock pump and put larger lines and fittings on and you are now seeing 7 psi - you still have the same flow, just lower pressure because you are putting the same amount of flow through a larger area - hence less pressure. A perfect example of this would be for you to take two straws - one a coffee stirrer (very small line) and a 32 oz big gulp straw. Blow through both of them lightly and then blow through both of them hard. You'll find that when you blow through the small straw hard that you'll feel more resistance - that's pressure. Blow through the big straw hard and you won't feel that resistance - but you are flowing more air.



The reason that D/C and cummins use fuel pressure for a measure is because it is WAY cheaper and easier to measure pressure than flow. What you have to keep in mind is that their pressure specs are based on stock fuel lines and fittings - increase the size of those lines and fittings and those pressure specs are no longer valid because the pressure required to attain a certain flow rate is now different. That is all based on the assumption that the most restrictive spot is at the VP44, if you had a greater restriction back in the fuel system somewhere (like the banjo bolt coming out of the fuel filter house (or the fuel filter itself) if you open those up then you could see a higher pressure because you've removed a restriction upstream from where you are measuring.



The pressure spec that the Bosch engineer gave would be inside of the VP44 at the inlet to the low pressure pump. Unforetunately we have no way of testing the pressure at that point so we really have no clue what the pressure at that point is because there is no test port at that spot to measure from. I'm not sure where the return valve is located - my guess would be that it's before the low pressure pump inside of the VP44. If that's the case then we really have no idea what the pressure is at the inlet of the low pressure pump inside of the VP44. Someone would have to figure out the exact spot to drill and tap into the VP44 body and put a sensor there to see what the pressure is at that point. I don't think we'll ever know to be honest.

 

[RADdodge]

I started a thread on “Pusher Pump & PSI Solution,” but this thread is getting the action even though it took a big turn to it’s current focus with Eric’s post.



The trouble with the “Big” VP-44 thread was it got way off of the original topic and took a lot of side trips. I think the best place for the VP44 info would be the FAQ, but the information would have to be factual and not conjectural.



As far at the volume vs. pressure that I mentioned in the other thread, I couldn’t remember who came up with the fuel flow data (flow meter supplied by Bill Kondolay). I found the thread started by Chris Sutton and Mopar-muscle did the flow testing. It’s a great thread (for those that haven’t read it and for those that want to review it) Here’s the link:



https://www.turbodieselregister.com/forums/showthread.php?s=&threadid=11672



p. s. Did anyone ever come up with an exploded diagram of the VP-44 internals?