205K on my oringinal VP-44 and I just installed a new lift pump because it would drop below 5 psi wot. The new pump idle at 15 psi, cruise at 13 psi, wot at 10 psi. A good 5 psi higher across the table than the old pump. I've only used additives a couple times. The last 100k have been bombed, but I don't hammer it that hard!?!?

 

You would loose your bet! I always thought the same...part of me still does...but a survey on another web page showed no correlation between using an additive and not losing your L.P.
This survey supports the reports that stock trucks seem rarely to have L.P. problems (assuming an equal % of stockers use additives as do non-stockers).

Source of lift pump problems seems clearly to begin with higher HP demanding more fuel than the stock system is designed to provide, but there are other excellent reasons for using additives, IMO.

RJ

 

The topic is about the v- p 44 not the l-p. So, am I still wrong? I haven't read the other survey.
I would guess the l-p failures are more of a quality control issue.
This is one area that Dodge should of put a sensor and a check engine light. They didn't seen to care about us driving the truck with low fuel pressure as much as they did about us raising the trans line pressure!!! ( this will set it in limp mode, unless you correct their engineering.)

 

Everyone is keeping on topic. The lift pump IS THE REASON for the VP failures. But the reason the LP cause's the VP to fail is because the stock fuel lines are to restictive for the bypass system in the LP. There is no quality control issue, it is more like a faulty engineering design. The LP's are very good quality. And I have heard (from a ex dodge mechanic), but cant back it up, that the VP is designed to reduce power when the fuel pressure from the LP gets dangerously low. By adding a box you bypass this warning system and feel nothing, in which then you toast the VP.

 

This isn't so clear to me. Many LPs fail on stock trucks. The anecdotal evidence suggests that the failure rate of LPs does NOT correlate to bombed or not. It seems more to correlate with model year and a host of other variables. In fact, it seems there are so many variables that it's hard to even say that LP failure rate even correlates to anything. They DO seem to hold up better on 01s and 02s, but maybe that's just because they are newer or have fewer miles.

It is my PERSONAL OPINION that the VP44 kills the LP. In a sense, the VP44 commits suicide. It has these high pressure pulses that get sent back through the line, which kill the LP. Then the LP dies, and then the VP is starved for lube and dies, too. Thus, VP suicide. Who knows? There's just no way to say for sure.

Many LPs fail at the bypass spring. It simply fatigues and gives out after opening and closing a million times. I've wondered if regulating FP below the bypass point would prevent this.

Some fail with brush/armature damage.

If you have a mechanical FP gauge like I do, you can sometimes hear the pressure spikes that the VP sends back to the LP.

Then consider that the pump is bolted to a hot, high-vibration engine block. It's a wonder sometimes that they don't fail even more often than they do.

Maybe bombing does have an effect on LP durability. But I haven't seen anything to suggest that this is the case....

Justin

 

AlpineRam,
Did you run a loop in the rubber hose? We run large positive displacement pumps at work and have had some success by running loop to absorb the 'shock' from the pump. In our case it was done to stop tearing welds on stainless pipe, but same principle.

DuaneWKKC

 

I didn't run a loop due to space restrictions, nevertheless I have an ascending spiral towards the fuel filter. Only downside of the rubber hose is that you've got to be extra careful about rubbing.
I found that cracking welds on equipment sometimes came from engine vibrations being translated into cycling push/pull forces on hardlines in the weirdest places. I prefer soft hoses whereever applicable and try to shoot for one size and one sort of fitting throughout one function on the machine to have less parts to stock and still easily identifiable lines to keep repairs simple.

AlpineRAM

 

This subject has been batted around for the last 4 or more years, and always seems to fall back to the lift pump as the single cause of failure, even though the real answer was known at least 3 years ago.

HOHN is spot on concerning the lift pump. Move the pump off the engine and put it back on the frame, by the tank, and it's problems will go away. There's a much less harsh of an enviroment there. In the early days, many folks did this and haven't had troubles since. These Carter pumps are pretty good units and always get a bum rap, especially when you consider that no other pump has had any better of a performance record when bolted to the engine.

Certainly, a lift pump failure isn't a good thing, but doesn't necessarily mean instant or necessary death to the VP44. I know of trucks which have operated at negative fuel pressures for surprising periods of time that are still alive and well today after 1000's and 1000's of miles.

The choice of lift pump, and it's location, was an engineering decision of Cummins and not Dodge.

As for VP44 failures, there are many reasons that cause them. Lack of lubrication is only one. Many die of electrical problems (maybe piercing the wire contributes to this), or rust caused by moisture in the fuel. There is a hard seal deep inside, dividing 2 chambers, which develops cracks in it from, probably, pressure pulsations (maybe lack of fuel pressure contributes to this). The VP44 guy at Industrial Injection, here in SLC, has a list of at least a dozen different failures which range from the improper installation of the Blue Chip cover, failure caused from extreme hot rodding, to just plain being wore out.

With respect to the addition of boxes and failure rates, Mark Chapel from TST has hard data, in terms of actual numbers, to suggest there's no difference between the addition of a box and no box. I know this because he publically corrected me on this subject over 3 years ago, while I was still learning this stuff, myself. These are numbers you can't get by polling forum members from this or other CTD enthusiast internet sites, which all together represent a very small percentage of all CTD owners.

That's my $.02. I don't claim to be any authority on this subject, but one thing I know for sure is 99% of every one else here isn't either.

 

If you want a factual answer on why the VP44 injection pumps fail, go to this site and read the article: http://www.bluechipdiesel.com/inject...pfailures.html

 

It might just be me, but I know of no other engine that has injection pump issues, like this, and if you notice on most heavy duty diesel engines, the injection pumps are mounted lower, so that there is more siphon effect.

Then again they all have there issues, GMs eat the the drive module and that requires the change of the pump, and Ford/International, have fitting leakage issues, you can try to reseal them, but if that fails you have to replace the pump, I would rather change a pump that died and no longer pumps fuel then to change one because the engineers didnt want to cool the electronics or because of an oil leak.

 

my VP and LP failed last week as well. Of course, when I asked the dealership how they failed or how I could detect or prevent failure, they weren't exactly helpful.

In the past 24 hours, I've read until my eyes were crossed and learned a great deal about the fuel delivery of this truck. I'm looking into fuel pressure, trans temp, and booster guages now.

Afterwards, I'll be doing more reading on relocating the LP.

Anyway, thanks to all for your advice and help. I, like many others I'm sure, wish I had done this research before the $2900 donation to Dodge.

 

Sorry to hear about your experience.

Curious about details....how many miles on truck? Stock? Any indications of a problem prior to failure? etc.

Would like to hear...and might help others in the future!

RJ

 

2000 3/4 ton. 109K miles. (of course it's just out of warranty, that's how it's suppose to happen) Everything but the CD player and shocks are stock. Unfortunately, I don't (yet) have a fuel pressure guage, so I couldn't "see" it coming. Beyond that, I had no indication whatsoever. Keep in mind that I do very little heavy towing and I'm not a "foot in the floorboard" driver. Literally, I was driving down the road and it quit. I had not noticed any loss of horsepower.

The only loss I notice is in my checking account.

 

Are you sure the vp was really bad? Dealers like to replace parts. I've seen them try to replace the vp and lift pump because of a clogged fuel filter. Just something to think about. My local dealers only repair a few diesels a year, they are not very good with them.

 

I have no idea. The fuel filter was only about 10K miles old. Like I said, I knew too little before I had it towed to the dealership (which is 30 miles from my home). I've had so few problems with this truck, I have foolishly not taken the time to learn it.