Engine/Transmission (1998.5 - 2002) Operation Lift Pump Longevity (long)

[dcochran]

DTT MECHANICAL FUEL PUMP



I've been very fortunate to have had this pump on my rig for some two months now. Being an Abbotsford, B. C. type (10 minutes from DTT and all the crew) and where it's easy to give and get almost instant feedback, I believe that the days of the "other" LP solutions will soon be history.



Think about it, a system that increases fuel pressure when RPM's increase - just what the 'doctor' ordered. This of course will require a major readjustment of what to expect when looking at your fuel pressure guage, LO versus HI pressures during idle and higher versus lower pressures when cruising - can't really do anything else 'cause the higher the RPM the more fuel the pump is pushing. What a novel concept - getting more fuel when that really expensive injector pump needs it. .



The OEM LP is still there. It'll be handy in order to prime the system after a fuel filter change or in the unlikely event you ran out of fuel. You could likely turn the engine over a few times and accomplish these tasks with the mechanical pump- still, a nice feature and because it runs briefly when first turning the key on you're ready to go as when the LP is functioning per design spec's. Should the belt that runs the FP fail the LP will come back on stream (it won't be running any other time, other than those maintenance requirements mentioned earlier, so should last the life of the truck) and you can change that belt in moments need be (you do carry spare belts don't you?).



As with most great ideas this one is "poetry in motion". Despite a mention earlier in this thread by, Edward, this is a really simple although well thought out and designed system with very few parts that will (has) make most of us wonder why we hadn't thought of it ourselves. I'd gone thru 3 LP's myself but am confident I won't need to purchase another unless somebody swipes it off the frame where it sits now. By the way, because it's no longer running all the time the noise factor is considerablly less - never realized how noisy that LP was until it wasn't running hour after hour - pure bliss.



Yes, there's a bit more to this system then what I've mentioned. I'm not the designer, just a fortunate user, so direct any queries you might have to DTT - this one is another of their many winners.

 

[Edward]

dcochran



It's good to hear a report about this new system. However I am curious how many miles you have on this new design? Are their any test vehicles with 50 or 60 thousand continuous miles on the new pump yet? This new pump system will be up against some tough competition. The Fuel Preporator for example has hundreds of thousands of miles on it's design so we consumers have a track record to look at. The life span of any design is what really matters to me, and I would have to believe would matter to most folks. It's all about reliability over the long haul. There is one point that I will respectfully have to disagree with you on. There is no need for higher fuel pressures at higher RPM's. If you can maintain 10 psi at all RPM's and engine loads the VP44 would have all the fuel it could ever use or want. Remember to maintain any pressure on the supply side of the VP44 you have to supply more fuel volume than the injection pump is capable of using by sending to the injectors, using for internal lubrication, cooling and bypassing back to the fuel tank. To create pressure you must have excess volume.



Edward

 

[rweis]

Edward,



Isn't it a little presumptous to wonder if they have 50k miles on a test vehicle? We all know testing takes time one mile at a time. As the new system is released and those that use it will validate its parameters. This "I want it now, it can't be any worse than the OEM" is not necessarily a bad environment. You get every conceivable range of testor, in every conceivable environment, at every conceivable skill level, all with great expectations and at the same time hoping it is an improvement over a poor existing design.



"Ya pays ya money and ya takes ya chances"



Each one of us determines at what point of the testing cycle we want to participate. If you want to wait till it has millions of miles of testing that's fine, it's your call. If I want to participate right now by going ahead and taking a chance, it's my call. But, DON'T tell me where and when I an going to make my own call.



I am testing my own fuel feed configuration, and will continue to do so until I feel there is a better configuration out there that I want to participate in.



Sure there is a lot of interest in a new possibility as there should be. So far as has been posted two users have used it one month and two months respectively. And then there will be 3 then 10 then 200 then 1000 and the weeks will turn into months and into years and the better it proves to be a good system the more "testers" there will be.



Let's see what happens, BK / DTT does have a reputation for DIR the first time (my opinion of course, see sig)



Bob Weis

 

[Ncostello]

We'll have to wait for DTT to bring this issue up.



In other news... I'm now pretty sure it is my bypass pressure valve on the VP44... and NOT the lift pump. I'll fill you in as soon as I can as I need to do one more thing with it.

 

[24V-DSL]

Bob Weis....

Well said... .

 

[paulb]

I also consider myself fortunate enough to have the opportunity to test DTT's pump setup. I've only put about 2,000 miles on it, but already I find myself not watching the fuel pressure gauge as much. In these 2,000 miles I've also raced at three drag races. It's nice to see 15psi on the gauge as you go through the lights (I know, what am I doing looking at the gauges!). I am very careful about what I agree to test. I have to believe in the products, before putting them on anything. I feel very comfortable with using this system. Right after I installed it, I went on a 1200 mile trip (including two days of racing), without a worry. StephanK, BillK, and all the others have done a really nice job with this system.



As far as adding complexity, this is really not the case. Yes there are additional parts, but remember this system runs in parallel to the stock system. That means that both systems are independent of each other. The total number of parts has increased, but the chance of total failure has been greatly reduced. DTT's system, IMHO, is less complex by far then the stock lift pump, especially when you include the electronic controls, that run the pump.



Anyone that has questions about DTT's system should direct them to DTT. They of course know much more about it. I just know I LIKE it!!



Paul

 

[Edward]

Originally posted by rweis

Edward,



(A)Isn't it a little presumptous to wonder if they have 50k miles on a test vehicle? We all know testing takes time one mile at a time... .



(B)This "I want it now, it can't be any worse than the OEM" is not necessarily a bad environment. You get every conceivable range of testor, in every conceivable environment, at every conceivable skill level, all with great expectations and at the same time hoping it is an improvement over a poor existing design... .



(C)Each one of us determines at what point of the testing cycle we want to participate. If you want to wait till it has millions of miles of testing that's fine, it's your call. If I want to participate right now by going ahead and taking a chance, it's my call. But, DON'T tell me where and when I an going to make my own call...



Bob Weis

Bob

I added the A, B and C to the quote above as a way to answer each section.



(A) No presumption at all. Total miles of testing are simply a way to tell me and anyone else who reads this the maturity of the design. We are all use to hearing outrageous claims about products. This pump has been called the Holey Grail of pump designs. If it has less than 50K if testing on it then in the scope of things this thing is still in training pants and not walking upright at this point. (JMO) Has it earned the title of Holey Grail yet? I don't think so but again that is just my opinion. Don't get me wrong it would be great if this thing actually worked and gave all of us more options.



(B) As far as those who go for the "I want it now" mind set you are right there is nothing wrong with it as long as the consumer understands they are laying out hard cash for a beta version. And that what they purchased may not make it to 50 thousand miles. Their money their choice I have no problem with that.



(C) "But, DON'T tell me where and when I an going to make my own call... "

I wasn't telling YOU or anyone else anything. YOU chose to read a post where I expressed my opinion.



PS. Perhaps we should take this new pump topic someplace else. I don’t think it would be fair to Neil to hijack his lift pump thread.



Edward

 

[Ncostello]

I'm not too concerned about hijacking... but it is getting more about mechanical pumps and less about the Carters. I'm afraid some will be reading this and miss my original concern with the Carters. Plus... some may not be picking up on the good discussion because they assume the posts are about something other than mechanical driven pumps.



Now... who wants to start a new one???

 

[Edward]

Originally posted by Ncostello

We'll have to wait for DTT to bring this issue up.



In other news... I'm now pretty sure it is my bypass pressure valve on the VP44... and NOT the lift pump. I'll fill you in as soon as I can as I need to do one more thing with it.

Neil

Glad to hear the news. That will be a simple fix for sure. I know you have put allot of hard work into your system. I hope it pays off for you.



PS Neil the posts in this thread about another lift pump should probably be placed under their own topic. If you have no objection and if we can get a Moderator to move them all I think it would be a great idea.



Edward

 

[Ncostello]

I'm fine with that. They can tell where we started onto the gear pumps I'm sure. I knew they could move entire threads to other forums... I wasn't sure if they could move posts to different threads. Its whatever they think is best.

 

[rweis]

I don't do, dueling banjo's.



I'll sit back in the grass for a while and watch.



Time will tell.



Bob Weis

 

[Stefan Kondolay]

Hey guys, just let me clear this up, DTT does not own this system. KO Engineering owns this pump kit and they know Bill through drag racing. They call it the RASP (rotary axis supply pump) Part of the arrangement is that Bill, DTT & a variation of their customer trucks would be involved in the testing in return DTT would get a period of exclusivity.



As Bill is very familiar with this type of system as he runs a similar one on his racecar that and his candor allowed us to participate. To answer a few of your basic questions, if you do happen to break your belt even though it is a long shot, but **!! does happen. The RASP system will not leave you on the side of the road even with a broken belt. A light will come on indicating the belt has broken and your original system will automatically come on. The RASP system runs parallel with your existing system. There is a pressure switch that monitors pressures and will automatically energize the electrical fuel system. So if your belt breaks the system will detect it and your electric fuel system automatically takes over. It only takes 1/6 hp to drive this system and no electrical draw. It will self-prime up to 10 ft straight up vs the electric fuel pump that has to be gravity fed for longevity.



The RASP pump utilizes a stainless steel bearing and straight cut gears housed in cast steel. There is no fuel regulator in this system as the diaphragm is unreliable and can burst causing problems. Instead it uses a bypass system that runs parallel with your existing system.



All the bracketry is CNC machined & designed to be direct bolt in. All the necessary bolts come with the pump. While a suggested plumbing parts list comes with the system the plumbing portion of the kit is left up to the individual installer preference.



Some of the features I personally like about this system is that it is quiet, reliable & the fuel pressure increases with engine rpms unlike the electric fuel pump that requires high idle pressures which can damage your vp 44 pump and in some cases can cause hard starting. This bypass system you set the pressure and it maintains it under high load conditions. I feel a little proud of this system as around our shop I was fondly referred, or at least I think it was fondly, the pump killer. Those of you guys that know me know how many pumps I went through. Many different trucks were used and for different periods of times, a lot of the testing stayed inside the drag racing circle to minimize the reverse engineering before official release. Some of the test trucks were tdr members like Opie 2001 , Idahoctd 2004. 5 , t berry 1998. 5 ,paulb 2002, dcochrane as you saw above is a 2000 in place of my 2000 that I lost in the accident. I am going racing now guys but got the ok before I left from KO to put this up.

 

[Ncostello]

Your going racing... and I'm sitting in my office with no windows



Thanks for the information. I'll stay out of this as it appears to be over my head. I just saw what I saw at Muncie.



I'll keep my eyes open for it. I'm personally glad to see the plumbing is left up to the installer as I like to do things differently than most kits anyway.

 

[Ncostello]

Back on track here with Carter lift pumps



Spent a little money ($30) at Scheid Diesel and got me a new overflow valve. That would be the banjo bolt on the VP44 return line port. It has a spring and ball in it to allow pressure above 15psi or so to return to the tank. Excess fuel I guess (which sounds strange considering everybody wants to feed it alot). Once that valve opens it should flow a decent amount just like a banjo. It also has a small port in the side of it to allow for air purging I believe during filter changes. Somewhere on here is a cutaway diagram of this area of the pump and how the valve works.



Before I switched... I keyed the ignition on and the pump ran for 2-3 seconds as usual building 15. 2 psi on the Dakota Digital fuel pressure gauge. Thats what it always does. Then with the key left on, but not started, I hooked up my test plug with leads. Running the pump on 12V and the VP44 not running I could dead head 15. 4 psi constantly.



After replacing the overflow valve, I could dead head an even 16. 0 psi on the gauge. This held constant for as long as I had the pump running. I unhooked the test leads and hooked everything back up. At this point I began to wonder.



I started the truck and no dice. Still 1 psi off on idle at 14. 4 psi. Usually at 15. 4 psi with the engine running just as when I was dead heading the pump. Pulling it down to 12 and below while accelerating is still easy. That was something very different than before. Thus the problem only exists when the truck is running. Now at this point some of you may think I'm crazy for worrying about 14+ psi at idle. But its different for me and there must be an answer.



This proves a couple of things for me. The lift pump must be OK as I can build 16 psi with it no problem. This is assuming the volume is still good. But I figure with pressure like that the pump should be operating OK inside. Any thoughts on this anyone??



Next the gauge must be OK as 16 psi was my dead head pressure all the time before the loss of pressure. I verified the gauge too with my 30 psi hydraulic gauge. Its all good.



So what went wrong? My guess after talking with Scheids VP44 rebuilder (they do that now and have all the equip) is that something internal is wrong with the VP. I cant check my codes if I have any (1999 truck). My truck has always had a strange rolling idle miss and perhaps its getting worse. Kinda sounds like it has a cam at times. My early VP has a diaphragm (metal with o-ring) that could be cracked. Thats common on early VP's. They showed me a cracked one and its hairline crack... but it might still run. Some crack in 4 places from the center out. It reminds me of a mini CD with an oring round the edge... cept a little thicker.



I have a spare VP off of another 99 with 10,000 miles. I'm gonna have them run it and check it. That takes two hours and is called a calibration test. Plus they can update the diaphragm with the new one. The part is actually cheap... like $20 or so. The test is under $200 more or less but worth it since I'm positive its a good pump. You obviously wouldn't want to do this on a pump that was known to be bad.



So... now its getting serious. But I've always wanted to be absolutely sure the VP is good anyway. Here's my chance. If this don't cure my pressures then I give as nothing else has changed and the lift pump seems fine.

 

[Ncostello]

Oh... I forgot. I wonder what would happen to the VP44 if you basically plugged the return port and didn't use a return off of it? Since that thing bypasses at 15psi... it would stand to reason feeding more than that would really be useless. There must be more to it than that. I'd say thats where the lubrication/cooling fuel leaves. Any knowledge if this is the case?

 

[rweis]

I know this must have been hashed many times before.



If the return is set at 15psi, does that mean anything less than 15psi is actually not good because no excess cooling flow?



But prior to the current flow testing at DC, it "used to be" ok as long as the lp put out 10psi at idle.



Something does not add up here. Probably my understanding is off, maybe by quite a bit.



Bob Weis

 

[Ncostello]

Good point Bob. I can't remember. It would stand to reason practically no truck would get any cooling flow since most lift pumps do not operate over 15psi while running. However don't forget this bolt valve has a port in the side of it which always allows return flow... as well as its main ball valve flowline. Even though the hole is much smaller than the main valve size... at 10-12 psi it would still shoot a decent stream of fuel. Perhaps enough to rid hot diesel. On fire truck pumps... the hot water generated when dead heading or during low flows can be sent back to the tank via a 1/4" line which is small in comparison to the 2 1/2" outlets. At least on our truck they figured 1/4" was enough to rid the heated water yet no allow full flow bypass.



My understanding of thermodynamics from college days gone by is that some amount of time is necessary for the cooling meduim (diesel) to remain in contact with the hot object (VP). Time is required to absorb the heat. Thus if it flows through the VP too fast and goes full flow throuigh the overflow valve it won't have time to gather heat. So maybe this un-checked port is what keeps the flow at a slow pace when under 15psi and helps with cooling. This would be the case most of the time. Just a guess.

 

[paulb]

I would also guess that the small return hole would help purge any air that got in the system. If the lift pump pressure was below the opening pressure of the overflow valve any air in the system (from filter changes, etc), would have to go out the injectors. The small hole will allow a return path no matter what the pressure is in the system.

 

[15w40]

There is one possibility that could account for the Carter pump having the same dead head pressure yet a lower pressure when the engine is running. This could be caused by a lower flow from the Carter pump due to the electric motor turning slower than normal. The deadhead pressure would be the same with the slower pump because the spillback valve will operate at the same pressure set by the spring pressure.



By the way, if the VP44 spillback valve stays closed, a diagnostic trouble code will be set to put the engine in limp mode for high fuel temperature; P0168. If the spillback valve sticks open it will cause hard starts and white smoke due to the lower pressure causing decreased timing and the inability of the high-pressure pump to prime for each injection event.

 

[Ncostello]

Thanks 15W40! Especially for the effects of the valve not opening or sticking open. Funny how a simple external gadget like that can practically bring a Cummins to its knees. At least I have a good spare.



You might be right on the money on the slower rotational speed. I hooked her up again to my test plug with battery clips and the motor sounds a little more noisy. Not the pumping sound... just the motor. Its got a slight squeak or squeal to it although barely audible. Wonder if its the bushings inside? Probably.



If it is... then clean, water free diesel and Stanadyne sure didn't help it.