Engine/Transmission (1998.5 - 2002) Modifying fuel system so temperature input to VP44, 80* - 100*, your inputs.

[Gary - K7GLD]

"But - I guess if you have one of the new re-designed VP boards then none of this matters huh?"



JEEZE, I wish!



Fortunately, we're not in as radical an ambient temp as some of you guys in the southland - and the darker trucks DO make significantly increase underhood temps, making corrections much harder for those who ARE concerned on that issue.



But all this is in the name of experimentation and collecting data - I don't think there's any harm or danger in getting the VP-44 TOO low a temp, other than the guys in the frozen north!

 

[Gary - K7GLD]

"The Fedex/UPS issue as I understood it was start cycles - the number of times it went through startup. Never recall any discussion of heating or heat cycles specifically related to the FedEx trucks. Two different animals. "



UMMmmm - maybe NOT "2 different animals" - again from Blue Chip's website:





"Now that out Bosch supplier can rebuild VP44 injection pumps, parts and repair information are now available. We have learned a lot from our customers and the pump shop and now feel we can offer a better whiz bang than the competition. All of our rebuilt pumps come with a NEW housing and a NEW computer on the top.

The housings on the VP44 wear out due to bad lift pumps causing the diaphragm in the front of the pump to rupture and the result in a short time is the housing wears to the point that fuel bypasses the piston and full advance cannot be accomplished which causes the code 216 and causes the truck to run erratically. This makes perfect sense to me as it explains why as 24 valve trucks get older the fuel mileage goes down steadily, and when we replace the injection pump with one that has a new case we get the mileage back! In a typical rebuild, if the case isn't worn out completely and the timing can be reached on the test stand then it passes the test and a partly worn out case gets to the customer, just to fail sooner. It should also be pointed out that the NEW housings have a brass insert for the timing piston, rather than plain aluminum.

The other issue is the computer on the top of the injection pump. The computer gets intermittent and eventually dies because of too many heat cycles. When you shut the truck off the latent heat in the engine heats up the computer and after many heat cycles the solder that holds the electrical components to the circuit board becomes crystalline and no longer makes a good electrical connection causing intermittent drivability issues, and eventual pump failure. Our experience has indicated that if you have a code 216, you also have drivability issues, that were simply solved by the replacement of the injection pump. Federal Express experienced so many failures that they convinced Bosch to make them a special computer to deal with this issue. Well as you have guessed by now, all of our pumps come with a new Fedex computer. We have been selling these pumps for almost a year and out custompers that haul RVs for a living and do crazy mileage per year have not had any injection pump issues to date. For this reason we feel confident we are selling a better product and value.

A pretty smart thing to do to save money down the road is to install a low fuel pressure warning light. It is true that when the lift pump can no longer supply enough fuel/pressure to the injection pump, the injection pump will fail soon thereafter. We have come up with a low fuel pressure warning system kit to give the driver an advance warning it is time for another lift pump. "



You might want to re-think your opinion...

 

[nps]

Gary - who do you want to believe - Bluechip or Bosch?



You posted the following response that you got from Cummins:

"Powermasters, I just heard back from Bosch on this issue. The upgraded board did not go into production until November 2002, well after this gentleman's engine was produced. However, he should note that the operating cycle of a UPS vehicle is drastically different from a Dodge pickup. The VP44 issue was related to the high number of engine start/shut down cycles (100s/day), seen by delivery vehicles, that was causing the failures. This is not a problem on the Dodge.



Regards,



Ken Scobel

OEM Service Mgr

DCX Account Team"

With 100's of start/stops a day, there is no heat cycle issue - the VP never cools!



You may want to rethink your opinion... (or at least disclaim your own posts!)

 

[Gary - K7GLD]

Gary - who do you want to believe - Bluechip or Bosch?



You posted the following response that you got from Cummins:





With 100's of start/stops a day, there is no heat cycle issue - the VP never cools!



You may want to rethink your opinion... (or at least disclaim your own posts!)

NAH - you win, underhood heat buildup is NO problem for the VP-44 electronics - Blue Chip and Fedex have it all wrong, and it's all Bosch's fault for building some mysterious solid state component inside that VP circuit board that was designed to suddenly fail after "X" number of starts (wonder how they do that, and what part that IS... )



BUT no, heat has NOTHING to do with it, and shame on BC for misleading us that way!

 

[Texas Diesel]

Gary, you are such an *****



I guess every site has to have a "know it all, post a reply to EVERY thread" like you. Get a life.



Guess others are getting tired of windbags like yourself.

 

[nps]

Gary - the two points I made were:



1. Heat is an issue - IMO its more of an issue when the VP is running and is better dealt with through cooler fuel inside the VP versus externally blowing air on it. Of course, both methods would be better.



2. Heat cycle (the heating and cooling of the VP) had nothing to do with why the board was redesigned by Bosch for FedEx/UPS as stated by Cummins. And yes, from a stress and flex perspective (that breaks solder tracks), starting with a 0* VP and heating it to 120* is just as bad as starting with a 100* VP and heating it to 160* - maybe even worse. Last I heard, heat never melted a solder track before causing a semiconducter to fail - tracks are broken by flex - but what do I know. I've only been around electronic board design for about 20 years.



Your attempts at sarcasm do you no justice. Your twisting of statements don't help either. You can't seem to separate the concepts of operational heat, heat cycling, and heat soaking.



But since you have all the answers, why don't you clarify with Cummins exactly what they meant by 100s of starts a day causing a problem for FedEx. After all - you were the source of that information and I guess you and I have two different interpretations of it.



I'll leave you to your thread and go install my fuel cooler.

 

[Gary - K7GLD]

... Thank God for this boards "ignore" feature - it's a pity more don't use it - it sure helps control blood pressure...



(click)





AHHhhhhh - there, that's LOTS better 2 more down...



Yeah, they might be compelled to talk ABOUT you - but they damn sure can't talk TO you!

 

[rweis]

Let's go have a beer (or beverage of your choice).



I'm going to start cooling my Pre turbo from 300* like I have been doing for a couple fo years to 200* instead on shutdown. Let the whole system get a little more stable and maybe a little cooler prior to shutdown and cooling fluids being stopped.



Bob Weis

 

[Mundgyver]

Well I did my run up to and back from Seattle last night. Left Friday and got back this morning about 1:20 AM. MPG appears to be up a little. On the way up I was in cruise at a steady state of 60 mph with the outside temps running at 89 deg F. On the way back we got caught in a 7 mile traffic jam/road work at 8 PM. So that took almost 2 hours of idling then we were back to 60 mph with outside temps at 63 deg F. The whole trip was 400 miles and I burned 1/4 tank by the gage. I was too tired to fill up last night, so tonight on my way home from work I will do my usual top out of the tank and get a good hand calculated mpg to post on this thread. Most of the trip I was watching the computer and it was giving me a reading of 28 / 29 mpg instant. Yes I know the trip computers are off by a couple of mpg, but for a reference indicator the numbers are up by about 2 mpg. So my curiosty is up at the moment wanting to know what the calculaton will be. I already can routinley do 720 miles on 30. 3 gallons with no problem. So a rough guess on my part, thinks that I will be better than this. We will see. I am at work at the moment and will post the #'s as soon as I can get fueled up and home tonight.

 

[rweis]

Progress report



Towed this weekend about 60 miles. The RASP will definitely put out the fuel at any rpm. Cruise O/D out 60 mph, pre filter 20 psi, pre VP 17 psi. Going up some little hills at 25# and just about WOT maybe 16 psi. Idle (in neutral) at a stop light 15 psi. Idle (in gear) at a stop light 14 psi. Very very pleased with the RASP.



Well, getting closer to fuel temperature test time. I installed the 1000 cfm fan this afternoon. I am going to run the fan on at all times (maybe not the winter time below 50*). The temp gun should be here this week (thought it would be here last week, coming ground though).



The objective is to take more heat out of the fuel than the VP can put in the fuel. At full tank the input temp will probably be OAT + some? (5?, 10?) due to road surface etc. Then send it back to the tank and cool it below tank tamperature. One of the old threads measured the return flow volume at high power settings at 30 gph, or about a full tank every hour. Cool it below tank temperature, then as the tank lowers I think the cooler will take more of an effect. It is a 30k H7B with 1000 cfm fan. Proof of concept will be the in line fuel temp sensor. I am puting the fuel temperature sensor in a 3/8 npt T fitting so the probe senses the fuel temperature, but does not interfere with the full flow.



Until the temp gun arrives I will do a fuel cooler and VP SOP hand check. Now the gun will not be totally accurate but I have the fuel temp gauge coming from Westach to give definitive answers and will cross check the gun with the fuel temp probe. We'll see how much difference there is due to emissitivity concept. That should be interesting as well.



From Mundgyver it seems we might have other side benefits.



Hopefully good actual data will be coming soon.



I think I will still do the cool down cycle to 200* on the pre turbo to help get the VP internals cooler before shutdown on a regular basis. I think one of the after market "turbo savers" will do that automatically. Might have to put that on the Christmas list.



Bob Weis

 

[Mundgyver]

Well I am deflated somewhat. My total trip mileage was 429. 2 and we used 19. 47 gallons of fuel for an economey factor of 22. 04 mph. This is down from my 23. 8 which I do routinely between here and Salmon, Idaho which is 720 miles.



I think the 2 hours that we were locked up and idleing in the traffic jam in Seattle last night is where and what ate my up mileage. My gut feeling and this is backed up by what the computer was showing was that we were getting something better and 24 mph, but I can only show what the figures compute out at. I hope to make a trip over to Salmon berfore winter sets in, so it looks like I will not have anything to show for awhile.



Sorry guys.

 

[Marco]

I've been away for a while, so I just saw this thread.



I have a fuel temp sensor in my truck. It's been there for the last 2. 5 years.

It's a couple inches before the VP fuel inlet. Homebreved stuff...



My findings. It appears that the highest fuel temps are due to heat soak.

I see the highest fuel temps in the summer after the truck has been sitting for a while with a hot engine. I think it's the fuel lines, filter, whatever goes through the engine bay that heats the system up. Fact is that if I start and drive the truck, I never see anything above 40°C ( sorry don't have my convert handy) ( something like 100°F). If I park the truck for a while the fuel temp climbs. I've seen up to 65°C...



Amazing is that it will then take a very long drive for the fuel temp to get back down 40°C. At least one hour...



Makes me think that if you want to keep the fuel temp down you need to cool the fuel before it enters the VP, not the returned fuel to the tank .



Oh yeah, during the winter I've never seen fuel temps above 30°C.



There has been conducted some testing of the HP VS. fuel temps a few years ago. I think it was Perkins? In short, they found the highest HP output @ fuel temps of 14°C, at 60°C HP was down by 7%.

What I've noticed personally, is that the engine smoke output is directly proportional to the fuel temp.



Helps some?



Marco

 

[Mundgyver]

Marco, what is the range on your temp gage and where did you get? How is the temp probe mounted into the fuel line? Is this a mechanical direct read or an electrical sensor style? Thanks for the info

 

[Marco]

The fuel temp gauge I've used is a simple oil temp unit with it's sender, made by VDO. Temp range is from 20 to 120°C. I've build a "T" which is tied into the fuel inlet line coming from the fuel filter a couple inches before it enters the VP. The sensor sits on the longer leg of the "T" sniffing right in the fuel flow.

With a little fantasy and some tools not too hard to figure out.



Marco

 

[Mundgyver]

That what I thought. Thanks for taking time to validate my thinking.

 

[rweis]

Interesting stuff!!!



Ok, I will do the testing of the return fuel cooler. I think that what Marco says about taking a long time for the fuel to cool down is (my theory) that the added heat to the fuel from the cooling of the VP then gets put back into the fuel cannister and is immediately recirculated. I put the VP/Inj return line into the tank vent line so it is totally mixed with the tank fuel. Also I am trying to remove MORE heat than the VP put into the fuel so the tank will actually cool down as the engine runs. Hence the time to get from OAT tank temp to a cooler temp should not be more than maybe 30 minutes (or less???).



If the latent under hood heat buildup is the (a?) culprit, then getting the shutdown heat out of the engine compartment is a point to consider. Maybe getting the heat out of the engine compartment quickly is a priority. Might be an interesting test to "pop the hood" and intentionally let the heat out and see what that does. Significant fans blowing the shutdown heat out? Ideas?



Is cooling the fuel before it enters the Vp = to flushing the engine compartment shutdown heat? IF you cool the fuel on the return to the tank?



More inputs, more ideas, and THANKS A BUNCH TO MARCO!!!!!!!!!! Long term data and observation is a real asset!



Bob Weis

 

[Texas Diesel]

Might be an interesting test to "pop the hood" and intentionally let the heat out and see what that does.

I've been raising the hood on my computer equipped vehicles for years during the summer, to the great amusement of my neighbors...

 

[rweis]

A $3300 amusement (to have a lp & VP installed incl labor) :--) will work, lol.



Hummmmmmm, the timer delays running a relay for forced large volume air flow after shutdown. The 1000cfm fan on the fuel & transmission coolers are 25 amp to start but only 7 amp running (for maybe an hour?). Mounted where?, blowing or sucking?, maybe suck the heat out with Gary's idea of a couple of tublar hose / fan setups and let them suck for an hour or two, they only draw a amp or two.



Maybe pop the hood?, but some neighborhoods are not conducive to that



Hummmmmmmmmmmmmmmm



Bob Weis

 

[nps]

Bob,



Have you thought about a pre-VP cooler in addition to your return cooler? I think that getting cool fuel to the VP as soon as possible after startup would be desirable, and also easier to accomplish than cooling the engine compartment.



Sounds like Marco's observations do support your theory that hot fuel is getting right back into the fuel pickup instead of mixing in the tank. If this is true, then you should see cooler fuel hitting the VP much quicker with your return line after a period of sitting. If you do, then you don't have as great of an issue with the underhood temps heating the fuel as a stock fuel return system has.

 

[Marco]

What about a fuel cooler that works off of the AC? Some kinda bypass of the R-134a to cool the fuel via an heat exchanger... . Just thinking out loud.



Marco