Engine/Transmission (1998.5 - 2002) Vp44 Failure Prevention

[SkipLieder]

I have read all the threads on the VP44 failures, and as a layman that needs to use my truck to pull my big 5er, I want to try to do the most economical things to ensure that my engine does what I bought it for, and for a very long time.

I would like some practical advice as to how to drive to protect my VP from failure. IF, they fail because of lack of lubrication, and that is caused by no fuel going thru it, wouldn't it be prudent to rev the engine from time to time when travelling down a long descent?

I use the recommended amount of additive in each tank. I don't know which is better so I alternate (a gallon at a time) between Power Service and Rotella DFA.

The thread on VP44's have convinced me to get a FP Guage, but I am firmly convinced that the way a person drives has a major impact on the longjevity of their power train.

So lets hear some practical solutions to this problem, and if you do have to replace the lift pump --- what are the best replacements (again, from a longjevity and reliability standpoint).

Thanks;

Skip

 

[Whitmore]

Skip, you are doing everything you can do to protect the vp, monitor your L/P psi and use of additives is about all you can do, the L/P runs continually and 70% of its flow is not burned in the Cummins BUT is circulated thru the VP for cooling and lubricity and then returned back to the tank.

As far as what other L/P to use there has been much experimentation over the years and there is a wide variety of results some good and some bad .



Keep doing what you are doing, Kevin

 

[Ncostello]

I've spent hours and hours reading almost all the posts I could find on lift pumps and VP's. I've replaced a lift pump myself and have recently seen the inside of a tore down VP. I'm not an expert (otherwise you'd be calling me at Neil's Diesel Inc. ) but I know what I'm going to do after reading what works and what does not. And what works today sometimes does not tomorrow... and what works for some does not for others. Seems like lift pump topics are a hot topic right now... more than normally.



I'm going to increase the line size to full 3/8" or maybe 1/2" all the way from the tank to my OEM pump. Then I'm going to place my OEM pump closer to the tank... but not all the way back. All I want to do is move it down until its right where the OEM line begins to come up to the engine... almost directly under the drivers feet. That way I'm at least putting the pump at the same level as the tank. Going the extra foot or three back to the tank does not seem to me to be that great of a benefit. I plan on putting a shutoff valve back there.



I'll extend the factory wiring to the pump, run 3/8" up to the filter housing, and maybe... maybe... eliminate the banjo fittings with smooth radius elbows of a -6 AN size. I plan on using Aeroquip socketless fittings and hose.



All this will do for me is eliminate most of the vertical distance the pump is required to overcome on the suction side, reduce friction loss in the "undersized" supply lines and fittings, and make changing the OEM pump much easier and faster (easier to get to) if the need ever arrises again.



I think the OEM pump is just as "up to the job" as any other aftermarket pump. I personally dont want two pumps, relays, and expensive aftermarket pumps. And I dont want to go outside the pressure parameters Cummins feels the VP needs. I am not of the belief that the OEM setup is completely worthless... it just needs a little help. I'll get a spare pump sometime, some spare sealing washers, and keep an eye on the gauge. If it fails, I should be able to replace it as quickly as changing a spare tire.



All I really want to do is drive the truck and feel the power. I cant afford to spend hundreds of dollars on this issue. I need to put my money in better places... like the tires. If it continues to be a major problem after all this, I'll buy a new one, a 12V, or a Harley . Again this is just my personal feeling and does not reflect on the solutions or suggestions others have had success (and failures) with. So please dont flame me for not suggesting what others have done to make it work better.



PS: If diesel dont get any cheaper... the Stanadyne is on its way out too. And I dont tow or work it so owning a diesel is really a personal choice for me. And I LIKE it!!

 

[Steve St.Laurent]

One thing that I've heard from several performance vendors and a couple of injection shops is that they've seen failures when someone was towing up a large grade and then went over the top and lifted completely for the descent. Evidently when this failure has occured the pump shaft siezes. One of the things that I do is when I'm getting to the top of a long climb when towing is that I slow down some before the top (I'm usually going way faster then everyone else towing anyways) so that when I go over the top I can stay on the fuel some rather than cutting it back to zero throttle right away. Whether this is helping or not I don't know but I have 120,000 miles on my original 98. 5 VP44 with 90,000 of those miles with a pump wire box hooked up and running.

 

[Gary - K7GLD]

Steve, forgive me for not remembering - too many threads and individual VP-44 habits to keep track of them all - but are you using a fuel additive on a regular basis?



I use Power service fuel supplement for it's lube enhancement, along with 8 oz. per 50 gallons ashless 2-stroke oil, in the hopes that assisting fuel lubricity will be a major benefit for the VP-44...



Time will tell...

 

[Steve St.Laurent]

Yes - Stanadyne performance formula

 

[GiesJ]

Originally posted by Steve St. Laurent

One thing that I've heard from several performance vendors and a couple of injection shops is that they've seen failures when someone was towing up a large grade and then went over the top and lifted completely for the descent. Evidently when this failure has occured the pump shaft siezes. One of the things that I do is when I'm getting to the top of a long climb when towing is that I slow down some before the top (I'm usually going way faster then everyone else towing anyways) so that when I go over the top I can stay on the fuel some rather than cutting it back to zero throttle right away. Whether this is helping or not I don't know but I have 120,000 miles on my original 98. 5 VP44 with 90,000 of those miles with a pump wire box hooked up and running.

It is very interesting that you wrote that as my VP44 kicked it last week coming back from Durango CO and I had just completed the climb up La Veta Pass on 160 and was taking it easy on the down side and the truck basically shut down. Thanks for the Tip.



Jason

ps - I run Power service regularly.

 

[me4osu]

I've posted this before, but I can't find it. Anyway, the link provided shows a test between some major brands of additive done by an independent lab.



Based on the results for wear scar diameter and cetane improvement, I use either Stanadyne Performance Formula or John Deere additive.



http://www.stanadyne.com/dsg/showfile. asp?id=1156

 

[Ncostello]

I've read the VP injects nothing when rpms are above idle and the fuel pedal is up (off), and I've read where it injects just a little. Guess Bosch engineers would be the ones to answer that.



Assuming the VP injects nothing when coasting, does the Lift Pump build up 15psi again and then cause the return pressure relief valve to open and send fuel back to the tank. . as if idling? If so wouldn't that keep fresh cool fuel flowing through the pump duing a coasting event. Just a guess here.



I plan on driving my truck without regard to where my foot feed is and whether or not I'm coasting or climbing. I've recently decided to quit babying mine all the time. With fuel prices so high, I'd like to coast as much as possible . I hope it holds up!!

 

[Gary - K7GLD]

Three things:



1. The above Stanadyne link doesn't work for me.



2. REGARDLESS of whether the VP-44 is actually injecting fuel while coasting or not, the pump pistons ARE still making their full stroke, and unused fuel is (supposedly) merely bypassed back to the fuel tank, just as it is any other time it is not actually consumed by the engine...



3. I'll be derned if I'll start practicing any devious "rituals", uphill OR downhill in hopes of preventing failure - I've taken all the reasonable precautions I intend to - this thing either lives or dies - and THAT'S it!

 

[me4osu]

Gary,

Go here http://www.stanadyne.com/dsg/dsg_dfa. asp

and click on MB2022.

 

[Big_Daddy_T]

Both of mine failed while i was on the throttle. Both days I was driving aggressively. One of the times I was pulling about 1500#s. I believe the prime- loc was a factor in both failures. Im proud to say Im prime loc free now. Heavy fueling box on the second ,Light fueling box on the first. I did a pusher like steves and believe it will outlast the truck now.



All you can do is use a good additive and watch your fp. Dont be afraid of a failure its not outrageously expensive. Just inconvenient. Think about 8 thousand dollar injector sets and 6 thousand dollar injection pumps and sleep well because you have neither. for under 2 grand you can replace all 6 injectors and your pump. For a little bit more you can go to a p pump and its oil lubricated.



I use stanadyne religiously. I buy it by the 5 gallon bucket. Another thing to think about is have no less than a 1/4 tank in your truck at all times. I think it was hvac who used a 5 gallon can one time instead of the regular tank. After driving a short distance with no hotrodding the fuel had gotten quite warm. more fuel = less heat. Also the less strain on the lift pump.

 

[SkipLieder]

Thanks for all your thoughts, they give me a lot more to think about. The recommendation to not let your tank get low makes a lot of sense. I am very happy that I installed the 98 gallon TFI tank that periodically pumps fuel from it to the main tank. YEA, I did something right --- what a bonus, because I bought it to increase my range between truck stops (keeps my shoes a lot cleaner) and didn't even consider that.

Keep em comin;

Skip

 

[TXRam]

I agree with Gary, the VP44 is a positive displacement pump, which means if it is turning, it is pumping somewhere (or else it will fail right then). It may not be injecting fuel, but it is pumping which means it must return all of the fuel to the tank. So I don't understand the whole coasting failure hypothesis. Can anyone explain this to me? Maybe because it is pumping against no back pressure (going to the tank), then when you get back on the throttle the pressure jumps up???

 

[Gary - K7GLD]

Since we've now heard from at least several guys experiencing problems when rapidly accelleration, then sudden letting off the pedal is involved - and at least one of those apparently resulting in a VP-44 failure - I have a question that maybe one of the experts can respond to:



We are told the actual timing of fuel flow from the VP-44 is controlled by the ECM thru the fuel solenoids inside the VP-44 (at least I guess that's where they're located). In this scenario, I assume the fuel solenoids function much like the valves in a combustion chamber - and the ECM is essentially the "camshaft" that controls that opening/closing and timing...



BUT, what if the timing or rate of solenoid operation is off - either by faulty programming or other factors that create a situation where the injector pump piston tries to force it's load of fuel out in a normal fashion, but the delivery-side solenoid refuses to open, creating a hydro-lock situation? Is that possible with these pumps, or is there a built-in override outlet fuel path to prevent the certain destruction of the pump that would otherwise occur?



Further, is it possible that some of the add-on boxes we use might aggravate the above scenarion even further - since it seems all the guys so far affected were using power boxes?



Comments?