3 years and 80,000+ miles ago I had to replace the VP44 and all has been well until last weekend. The truck now has aprox, 190,000 miles on it.

I move the truck around to move a trailer and I had no power in reverse. My first thought was I was up against a stump. I turned off the engine and looked and saw nothing in my way and didn't give it a second thought. She ran fine after I restarted the engine. Then this past Sunday driving to church in town, I pulled away from the drive and got the dreaded dead pedal again. I turned off the engine (rebooted the computers) and she ran fine. A call to Peninsula Diesel where I bought my last VP44 to learn these things are good for 80 to 100,000.

Is this true? any suggestions. By The Way, three years ago they were $995 they now cost about $1100

Doug

 

Pensacola Diesel is not the best place to buy a VP-44. They have an iffy reputation at best.

What do you have for a lift pump? Do you have a fuel pressure guage installed in the cab?

 

when it failed the first time I started by installing a Rabster, and can/have checked on the VP for incoming line pressure, I havent yet, I am still upset that I am having fuel problems again

 

You need to have a fuel pressure guage installed in the cab and you should have a better lift pump than the oem piece of junk.

Without those two items you will be buying many VP-44's - and you were lucky to get 80k out of a VP-44.

 

Dr. Evil is correct. Put in a Fass or eqivalent lift pump and it will double the life of the VP 44. You should see above 10psi to the VP or it will not lube itself properly.

 

thanks for the advice on the lift pump, They guys here had recommended that I replace it bigger/better last time I had fuel problems. If I remember its a Rabster pump for up to 1100 hp engines. The only thing I dislike about that pump is the tiny fuel filter on the intake side, I had to toss it long ago when I was stranded on the side of the road with a minute amount of dirt in it that clogged the filter.

 

It sounds like the place you purchased your VP has no real knowledge about the VP and simply sells them. The concerning part about that is, not only are they giving bad advise by trying to console you about the VP's lack of reliability but that they possibly have no idea why the VP fails at all. As you've probably read by now, the only thing which cools the VP is excess fuel over 14-16 psi of fuel pressure. Pump just enough fuel to the VP for the engine to run and you'll have a hot VP, and a hot VP will not last. The reasons the VP cant take heat is mainly because of the computer mounted directly on top of the VP. Its a known fact that computers dont like heat and to make matters worse, Bosch uses a lead free solder for the computer electrical connections. That lead free solder deteriorates under high heat situations and will eventually cause the computers electrical connections to intermittently and eventually fail. The signs of this happening are hard hot engine starting issues, puffs of white smoke upon that hard hot start, dead pedal, and loss of power/mileage. For this reason, you MUST know if the VP you're purchasing has a "brand new" computer or just one that worked before. Dont accept anything other than a new one and a VP which has all the newest internal upgrades. The VP's mechanical internals can take more heat than the computer but will also fall susceptible to wear and tear much faster when things are hot. So this is why its very important to make sure you have a good supply of fuel to the VP all the time. No more than 20 psi at idle is necessary and no less than 15 at WOT is becoming more the consensus.

 

Got any pictures of this Rabster pump?

It is also recommended to relocate any lift pump to the frame rail.
I'm on 10 yrs and over 200k on 1 injection pump so it is possible to get long life out of them. Fuel pressure gauge, pump relocation, big line kit, gear rotor lp are the upgrades. Not letting your tank get less than 1/4 from empty will also help cool the Vp.

 

Good after market fuel system, keeping the fuel level above the 1/4 tank mark are they top two best ways to make a vp44 survive. I run a 180 stat on the cooling system, 15 degrees cooler engine means that circuit board on top of the vp44 stays that much cooler.

 

So putting a higher psi fuel pump is going to allow more fuel to flow through the pump thus cooling it more? Splain this too me lucy!

If you're "heat" theory is true how come there are so many people from cold climates experiencing this issue. On the flip side I'm in the desert (113 degrees today btw) and I have many customers that have never had VP issues.....and a couple of these trucks haven't been taken care of the best. On the flip side I had to r/r my vp at 82K miles back in 2005. Stock lift pump was fine (12psi at idle/5-6 wot under load). I did change the lift pump a few years ago when ULSD hit the market as the top gasket started to leak (Cummins had a bullitin on this as well as a replacement part....replaced the gasket and have had the pump on the shelf just in case). If you were truely concerned about cooling the pump via fuel flow you would look at ways of providing more VOLUME to the pump, and mod the pump housing, return flow valve to allow more VOLUME to return to the tank. So when you install your big dollar pump on your frame rail and you have 15-20 psi at the pump all the time, how does your fuel return flow compare??? Ever looked at the smallish orfice in the VP housing where the fuel return flow valve hooks to the pump? I'm not drinking the "big pump more psi" koolaid, but am always looking for info to change my mind. FWIW I do monitor my stock system via a manual fp gauge. I have no argument that the stock style pump can fail, but I also believe that the above posts are not backed with any substancial evidence that they are correct or anywhere close.

....I've also replaced VP's with various fuel systems and customers in disbelief that it could possibly be the injection pump because they had the "pump of the day" on their truck.

 

I have to say that after as many posts as you have racked up, you're even playing like you've never ever heard this before. The VP has to be the most talked about subject on the 24 valve 2nd gen truck on any Cummins forum and the fueling system is always part of the topic.

So to respond to your question, comment, insult, or whatever you're saying.....
Yes, higher fuel pressure is one of the critical facts for proper cooling of the VP. Keeping fuel pressure above the factory preset Overflow valves 14-16 psi means that you are pumping more fuel through the VP other than what the engine simply needs to run. Because the VP is ONLY cooled by fuel, not doing this means that the only fuel cooling the VP is the fuel being used by the engine.....and the minimal amount which passes through the tiny 3/16" hole in the Overflow valves bolt. But pressure is definitely not all you want because pressure and volume are not the same thing. You can have one without the other so for that reason you need to have not only a fuel pump which can supply enough volume but one that can also supply the volume with enough pressure. Which is why fuel pumps like Airtex are not high on the list of desired fuel pumps.

The "heat" issue will always be less of an issue than in cold climates but its not the engine running heat which is the ONLY issue. There is whats called "heat soak" from the hot engine which the VP goes through when the engine is shut off for more than about 15-20 minutes. That causes the cooler than engine VP to match the temperature of the engine, which is about 50* hotter than it should ever get. This literally destroys the VP's computer thus creating most electronic failures. Some have even named this issue "hot start cycles" and are trying to link or determine VP reliability to how many hot starts cycles the VP has racked up under its belt. This is why guys who rarely shut their engine off have fewer VP failures than guys who turn their truck on and off multiple times a day. Living in a hot climate only exaggerates their chances of hot starts too.

As for fuel return..... You're asking a good question. I'm an advocate that running a 150 GPH fuel pump is not necessary unless you're pushing huge HP and no one has really bothered to figure out if pushing all that extra fuel through the return lines poses a possible unknown issue or not. Running a 100 GPH pump is totally fine since the OEM lift pump was capable of that in the first place. This is another reason why any fuel pressure over 20 psi just isn't necessary. But.....I will say that your mentioned stock fuel pump is NOT fine by putting out 12psi at idle/5-6 wot under load. Thats just to low all the way around. You can gamble with this if you want and possibly just win, but a gamble it will be. Most guys who think this kinda fuel pressure is OK will replace their VP.

Point being is that you went as far as to say that you believe that the above posts are not backed with any substantial evidence that they are correct or anywhere close. This is a pretty bold blanket statement which says that after a decade of research and effort, no one knows anything, and thats just not only wrong.....but kinda insulting as well. You can think what you want but the evidence is obvious. Run a good high volume fuel pump with fuel pressure between 20 idle, 15 WOT and you will have a VP which will last far far longer and possibly last indefinitely. But with that said, reliability is always going to be skewed by variables like guys who notoriously run their fuel tanks low on fuel, running timing/fueling boxes, tapping the VP wire, purchasing VP's from vendors who aren't selling updated VP's or VP's that dont have brand new computers, old VP's that were run on low FP before with new fuel pumps, or running out of fuel. The VP has come a very long way and is not the same injection pump it was 10 years ago. We dont know "everything" about the VP but unfortunately there is no other entity like Bosch who is willing to help so the burden is on the backs of the consumers. But we can say that we know a ton. No ones forcing you to drink any Koolaid and you're more than welcome to run any fuel pump you choose. This is the great part about these forums.

 

Looks like I stepped in something here.

My replacement fuel lift pump is mounted on the rear frame rail with a much larger fuel line from the tank to the pump and from the pump to the fuel filter. As I recall the pump manufacture that was recommended here when I last had the problem was something called 'Rapster'?

There have been a lot of good comments on the VP, and the one that caught my eye was the mention of the remanufactures that are updating the pumps and using new computers.....not that any old computers were re-useable.

Who makes a good....and affordable rebuild?

BTW, our Dodges are old enough to have used the lead based solder, they were made before the lead free or RoHS agreement with manufactures removing lead from circuitry. New & replacement manufactured electronic equipment after July 1, 2006 uses lead free solder. The older lead solder melted at 180* C, the lead free melts at 277*C

Isn't pressure just restricted volume? if so just increasing the pressure won't cool the pump, it would just have ample fuel for wide open throttle.

***What are your thoughts on drilling out the return line fitting increasing the return volume, then increase the fuel lift pump pressure to a sufficient pressure for the VP. The additional flow should then cool the injector pump & computer better?

 

What brand fuel pump do you have on the frame rail? And the recommended fuel pump you were thinking of was Raptor.

As for re-manufactured VP's, the concern with new computers is not that they were being re-used per say but that if the VP's failure was only mechanically related then the mechanical problem was fix and the working computer was left in place to continue its service, only to fail not long after. This is why its very important to find out if the VP comes with all new updated internals or was the failed item the only part fixed AND does it come with a brand new computer.

Then talking about the lead free solder, all years came with and still come with lead free solder. Thats probably the biggest issue related to failure problems with the VP too. There has even been attempts to relocate the FPCM (computer) to a more heat appropriate location but that only caused electrical interference issues with the extended wiring which caused more problems. Not saying it couldn't be done properly either but as its important to point out, the only ones who take the time to try stuff like this is consumers. And how many guys have a few working VP's laying to test on?

Yes pressure is simply restricting volume but you can have little volume with high pressure or high volume with low pressure or high volume with high pressure, etc. Volume and pressure are not the same thing. So yes, you're right. Turning up the pressure on a fuel pump incapable of supplying enough volume and or using inadequately sized fuel lines is a waste of time. You need both to do the job properly.

Drilling out the return fitting isn't what you want to do either. And for that matter, its been tried too but the Overflow valve is hardened so it wouldn't be easy. Not to mention, would messing with the Overflow valves setting be the right thing to do or is there something magic about the set 14-16 psi which keeps the VP working? If you wanted to do anything, you could increase the size of the return lines to help get the fuel back to the tank but there's more than lines to deal with. You have a banjo at the back of the head and you also have a T fitting just below that which would need to match the flow of the increased return line size or there would be no point in doing anything. Really the return line size isn't an issue, or should I say, it hasn't become an issue yet which anyone knows about. Running the proper amount of fuel volume is whats important and trying to shove more than what is needed "could" be an unknown problem since you wouldn't want to create an issue where you "pressurized" the return lines so much that you made it difficult for the VP to pass unused fuel. The way I see it becoming is that these aftermarket high volume fuel pumps which are capable of 150 GPH or more, will have to come with regulators that would allow any excess volume to return back to the tank via a new return line besides the OEM return. That way the VP would be getting all it needs to run and to stay as cool as possibly but the OEM return lines wouldn't be over taxed. It would have to be done right and was just a thought.

 

The "14-16" psi for the overflow valve is for the p7100 pumps on the 12 valves. The overflow valve for the VP equipped trucks is there to merely create resistance to fuel return (keep fuel in the pump). My info on this came from Cummins. Also the return valve has a 3/16" orfice which runs into a ball spring set up that will fully seat with about 1.5 to 2 lbs of force exerted on it. In a stock situation the stock pump will flow plenty of fuel to feed the injectors plus return flow on this smallish passage. The VP also has a hole about the same size casted in it where you screw the valve in so merely modifiying the return valve won't end up with the more flow results you are looking for.

 

Jbody, you had better have more than 14-16 PSI for a P7100 even at idle.

22-25 at idle and 32-35 at WOT is more like it.