KATOOM

With that info Mike, do you have a tool for meansuring fuel temps and comparing the outlet return line temperature in relation to the PSG cover temp?

I will add to this that within my constant pursuit to understand what’s going on with the VP and trying to alleviate heat soak as much as possible, Without another gauge to tell me what the fuel temps are, I have this habit of opening the hood during various drives and ambient temperature driving conditions and placing my hand on the top of the PSG to see how hot it is. Generally after short trips its only warm to the touch. After coming back 15-20 minutes later its much hotter. With longer drives its temp is considerable hotter but still tolerable to hold my hand on it. And again, after coming back 15-20 minutes later, its even hotter yet. During triple digit weather it can get pretty darned hot to the touch and after this last towing experience in the mountains when I reached my destination I quickly popped the hood and touched the VP and.....it was HOT. How hot?.....obviously I'm not sure since I have no gauge to check with but I can say that I wouldn’t have wanted to hold my hand on it for more than a couple seconds at most. So with that crude measurement, I'd say it was well above the 160* range.

I really cant answer that mike. And by no means am I proclaiming to be some savant on this subject but more that its a topic which I feel needs attention. Maybe your custom fuel timing changes you've implemented are contributing to cooler fuel temps inside the VP. Thats a shot in the dark but I cant discredit the fact that your scenario is not "normal". Also, maybe you're not building the underhood heat you think you are. Do you have the ability to read fuel temps? I cant remember.....

No you wouldnt because the fuel heater wont start "heating" fuel until it recognizes 45* F and it turns off at 75* F. Unless this fuel temp is being read inside the VP and not at the fuel filter housing.....

Valid points rancher but we already understand that heat "soak" after shutdown is a problem. Which is why others have tried to come up with devices or ways to run a fuel pump after the engines shut down for a set period of time. With that said, I'm not address the heat soaking problem at this point since all I'm after is a reduction of fuel temps while running. Having the ability to read fuel temps are limited to a few people with very high dollar scanners or some Edge chips which monitor fuel temperature. Others who care have resorted to laser temperature thermometers. Either way, all have found very interesting data and repeatedly read fuel temps in the 150*+ range. That’s HOT and even if you have a constant supply of fuel pumping into the VP, combine running heavy long uphill grades in triple digit summer heat with the engine coolant peaking in the 220* range, the VP is going to get hotter as well and the fuel temp will rise or loose its ability to dissipate enough heat if its already being delivered in the 140*-160* range. Dropping the fuel temp coming into the VP down to ambient levels will HAVE to have an affect….. Yes, the electronics are most affected by heat soaking but who’s to say that the problem with the PSG electronics isn’t being additionally aggravated by overly hot running temps in hot weather? Again, this isn’t something new to the diesel world. Just for sake of interest…..if you're not bored after the first few pages of posts, here is a couple very deeply involved threads from other forums who addressed this issue many years back to current date. http://www.thetruckersreport.com/truckingindustryforum/trucks-eighteen-wheelers/185639-anyone-install-a-fuel-cooler.html http://www.turbodieselregister.com/threads/135952-Modifying-fuel-system-so-temperature-input-to-VP44-80*-100*-your-inputs?highlight=dead+pedal

I honestly can’t comment on the algae issue for these trucks either. Although I have seen the algae topic tossed around before but I never saw reason to be included. Maybe now I will and see if there's any connection to heat. In saying that, I do know people with other diesel trucks and especially one person with a 7.3 Ford who has suffered from a tank so dirty that he had to have someone drop the tank and clean it out. Now I know this person fills his diesel tanks at all the places located in this small area where I fill up so unless he happen to tap into a fuel station who did nothing but pump dirt in there, I think now that his dirty tank issue may have been part of what we're talking about. He tows some heavy equipment on a regular basis with this truck and I can speak from experience when driving with him that this truck gets HOT when he's towing things. Maybe a connection.....?

Mike, I agree as I dont think mounting any cooler in a vulnerable location is a good idea either. And it seems mounting it up front and away from any drivetrain secondary heat interference would be the most logical since were after fuel temps at around 100* at the highest. I'm really serious about this guys..... I've been delving into the subject and I'm amazed at the information I've run across so far. Diesel fuel coolers are ANYTHING but uncommon. Its seemingly more uncommon to NOT have them but yet we see throughout the years that OEM is always cutting corners so if they can get around something which "may" not be needed then your vehicle will come without whatever device that may be. And the reasons for the diesel fuel coolers is always in regards to injection pump reliability.....but then tends to take a turn and spawn into a discussion about the density of fuel and HP and fuel mileage. And another very interesting subject which I found resulting in looking for coolers was algae..... Just as we regularly talk about oil "cokeing" in the turbo bearing from excessive heat, there is a situation called "asphalting" the fuel whereby diesel fuel is over heated and literally cooked to the point of thermal separation which results in a black tar like substance that’s prone to collect in the fuel tanks and fuel filters…..which is unknowingly categorized as algae from water and debris contaminants. A topic more discussed in class 8 type trucks but apparently or potentially a plaguing problem slipping under the radar for lighter duty diesel forums. We all know how hot the fuel can get in these injection systems so it must be something the diesel engine industry is aware of since as I mentioned before, the number of diesel engines with a fuel cooler is higher than those without. And in regards to "where" to place the cooler..... Well after the tidbit of research I've done, the return line is the general location based on trying to reduce the fuel temp before its dumped into the fuel tank, but there is plenty who mounted theirs on the inlet side before the injection pumps. And since I'm after maximum fuel heat dissipation just before the VP, I think mounting a tranny cooler with an electric fan as close to the VP as possible yet remaining in front of the radiator, is where I want to do this. That said, I may also place a secondary smaller less BTU rated flat cooler on the return line side mounted to the frame and up away from debris. Just to offer some additional offsetting of heat coming off the VP and head line as it flows back to the fuel tank. Remember, the fuel module has both the inlet and return line dumping directly side by side into the basket which means the hot return fuel is most likely being sucked right back up into the supply line. Keeping fuel in the tank at all times is the only way to combat this as sloshing fuel should counter affect but you can see under high fuel demand where this would be a problem. That is unless you have fuel coolers….. I'm also wanting to install a couple temp gauges via two 1/8” port fittings, maybe a dual temp gauge from Westach, so I can watch the supply and return line temps and see whats going on while driving. Like I have time to watch more gauges….. The only problem is I'm running out of (ran out of) places to mount gauges and I dont want to clutter up the cab with silly gauges mounted in various obnoxious manners for sake of research. Again guys, if you think this is a waste of time, do a few various and simple Google searches for things like diesel fuel coolers and you’ll find a plethora of applications and discussions. Its not a very “knowledgeable” topic as people tend to overlook the true reasons for the purpose but nonetheless, when you run across the guys who understand whats going on then the lights bulbs start illuminating and you realize that this is something these VP truck MUST have…..

I dont want to railroad an awesome thread but I'd like to touch on the topic of fuel cooling via a fuel cooler of some sort. I just have this crazy premonition that there needs to be a fuel cooler on these trucks. Given what I recently experienced while towing a very large trailer in 100*+ weather uphill with the engine at 215*-220* and having the throttle do something unexpectedly weird, excessive fuel temps or just plain excessively hot PSG is becoming very likely the culprit of what happened. I'm going to be digging into this topic really heavily and searching for an optimal small radiator to mount somewhere under or in front of the truck. Possibly with a fan assist too. There is just too many other trucks/diesel vehicles utilizing a diesel fuel cooler. In saying that, I've wondered if anyone has ever considered trying to cool the PSG itself. Chip from Bluechip told me around a year ago that Bosch has implemented thicker heat sinks under the PSG but I can’t confirm this and he's not around anymore.....that I know of. Then I got to thinking about a Peltier Module..... Why hasn’t this been considered????? Maybe it couldn’t offset the heat dissipation needed but I think using a $20 Peltier Module and sticking an aluminum bladed computer CPU heat sink to the top of it would have to help. Here's a video of what this device is if someone doesn’t understand what I'm talking about. https://www.youtube.com/watch?v=9Cuh2msd2lo If someone was so inclined they could install an inline thermostat too so it didn’t run in the winter. Maybe this would be better served in another thread but I think its a topic which needs to be revisited again.....

Why detune?

Not sure what happened to this thread since it was going gangbusters with information but just kinda petered out.....but an awesome read at that. GREAT information and it only took a decade for someone to tear down their VP instead of claiming the core fee. I commend Mike for the hard work and diligent picture taking too. Very descriptive info and even though I can see that maybe lots of this was a terrific recap of wandering data collected over the years, it was great to see it all poured out in one thread with pictures to back it up. Not sure why the on going confusion about the diaphragm though since that picture with a C shaped disc may be an actual diaphragm but an old plastic version which was broke. Who knows but it does look like the item called a "diaphragm" which simply separates the low and mid pressure sections of the VP. And the original VP's did come with a weaker thin plastic diaphragm which over time was thickened up and covered in metal.....so Mike has discovered. Yes, the chances of a diaphragm issue these days is highly unlikely if you have a remanufactued VP. Really I think that the mechanical side of the VP has been resolved but it sure would be nice if we could resolve some of the issues on the computer side of this pump. There's still just too many threads resulting in PSG issues but yet plenty of strange foriegn websites showing how we can buy new ones and replace the PSG while its sitting in the truck. Why arent more people doing this????? It doesnt seem like an involved task either but then again, thats me watching youtube vid's through a computer screen. And unbeknownst to many, the VP44 was factory equipped on A LOT of other vehicles besides the ISB Cummins. I still want to believe that the PSG can be dismounted from the housing and held up in some fashion away from the heat. Even relocated to a more tempid environment would be nice. But thats something only a few limited people have ever tried and the results are rarely discussed or even brought up. It would seem to me that there's no reason to spend a grand on something we can fix for a few hundred and half the time it takes to remove and replace the whole unit.

I didnt think of an ECM issue. And yes, the way you described it Moparman as limited pedal is more what it was like. I would have thought if it was dead pedal then it would have done the some thing in 3rd as it was doing in 4th. My fuel pressure is always in the upper teen's and I run so much 2-stroke its almost stupid. Like I said, I go through great lengths to take care of the VP. I guess I'll have to make sure the batteries are in shape and see what the alternator is putting out as well. I cant remember.....can I test the alternator while the engine is running or do I have to bench test it?

I tow a 14k 5th wheel in the mountains and last weekend my stock clutch started to slip. The only "hp" related items on my truck is an aFe intake, 4" exhaust, and EZ so I should be around 300 hp at best. I called Southbend and Valair and their prices are considerable in difference which has me wondering what I'm overlooking. I know they're both very reputable clutches in these trucks so..... Valair's NMU70279-01-5SCE is rated for 400 HP. New 13" flywheel and organic clutch material. Aprrox $650. Southbend's 13125-OKHD is rated for 425 HP. New 13" flywheel and organic clutch material. Aprrox $850. I dont have plans for any HP add on's other than I "may" look at 50 HP injectors someday to help towing a little. I have no desire to reduce any drivability so thats all the HP I want. Which clutch would anyone suggest or may already have? Thanks guys.

Well I'm only hopping that what I just experienced isnt what I think it is but nonetheless.....this is what happened. This last weekend I took the trailer up in the mountains, as I've done many times before. As usual for the north state valley area, it was stinking hot outside and I was pulling hills in 100* weather. No fun either as everything just gets too darned hot when its like that, but surprisingly this truck does amazingly well in staying within the tolerable running gear temps. The situation I'm posting about occurred when I crested the top of one longer grade. I was at about 5500 ft in altitude, running in 3rd gear at around 2300 RPM, and the engine was on the hotter side peaking out at around 215*-220*. Thats the HOTTEST it ever gets too and only for a few minutes at longest. Having reached the top of the grade I shifted into 4th gear to let everything cool back down but strangely the throttle was non-reactive to any further increase in pedal. Weird, so I shifted back to 3rd and all throttle was normal. Then I quickly tried 4th again but still the same thing happened where it seemed the throttle didn't react to any increase in pedal. But back to 3rd again would result in complete normal throttle. So after holding 3rd gear for a couple minutes more at most I tried 4th gear a third time and this time the throttle resumed normal action. I have no idea what happened and it didn't do it again throughout the towing trip. When I got home I checked for codes but nothing. I cant tell you how much I go through to assure the VP is happy so why out of the blue I'd start to have issues, I dont know. Its 6 years old, I only shut it off when I NEED to, and I'd be surprised if I have 50,000 miles on it. I dug around the internet to see what others have experienced with dead pedal and found the same thing over and over again but of what everyone had experienced with dead pedal, the only thing I can say that would be similar was that it was hot and the engine was hot. I've driven in higher altitude enough to know that sometimes the throttle is less reactive in the thinner air but I dont remember it being like this. I almost thought the ECM was accounting somehow for the hot engine but that sounds like I'm reaching for something. In saying all this, I do remember feeling the dead pedal running in the higher 6k-7k ft altitude about 8 years ago with the original VP on the truck but if I remember right it was a complete but momentary loss of throttle control no matter gear or anything. What I felt the other day didn't seem to be like that but then again.....maybe I'm in denial.

Well I guess if you knew the pump was on its way out and you could be sure that this was the problem then really the only thing you'd be giving up is the core charge if you eventually had to just buy one. That is unless they accepted a core in peices.....

Hey Mike, there is no "rubber" disc diaphragm. Its actually plastic and the updated versions are covered in stainless steel for added strength. That said, there are little to no cracked diaphragm related failures you hear of anymore unless the VP is original OEM or replaced by a dealer with an off the shelf OEM replacement VP which hasn’t received the upgraded components. I've posted a picture of the diaphragm before but for sake of the topic, here's another one. Its the "C" looking thingy on the left. I cant say why you cant find it unless the parts are proprietary to Bosch certified people.

I completely agree..... Very respectable of you and I'm not here to bash anyone personally either.....nor any forums as well.

I saw that MnTom. Not sure where this guy has been for the past 10 years.....who also claims to build pumps.

Increasing the diameter or the fuel line allows a for larger amount of volume (stock) to flow which in turn means that the fuel pump does not need to work as hard to supply the demand required by the engine therefore the pressure drop is less throughout that range of demand. That said, the smallest diameter in the fuel line is still the most restrictive point in the system so if the fuel module is 5/16” but the fuel line is 1/2” then the true amount of volume is dictated by the 5/16” opening. But…..thats doesn’t change the fact that there is a long larger diameter 1/2” piece of fuel line after the restriction which is holding excessively more volume to offset the demand loss. And worth pointing out is that if the engine used more fuel than the 5/16” size fitting could supply at any time then the whole thing would be mute.

I think the "normal" expectations of pressure drop for the higher pressure / higher volume aftermarket fuel pumps and 1/2 inch fuel lines is in the range of 3-4 psi from idle to WOT. That said, under normal conditions, additional fueling and/or fuel line size will play a part in that. What I mean is, running the same size fuel lines, you can’t expect someone running 150's and an Adrenalin to have the same pressure differences from idle to WOT than someone running only an EZ.

Basically the reason for a "minimum" amount of fuel pressure began was so that the fuel pressure from the lift pump was equal to or greater than the internal low pressure side of the VP. This pressure equalization kept the VP's plastic diaphragm from vibrating from the hydrodynamic pulses sent down from the higher pressure rotor. So as time went on it was also conjured up that if the VP's overflow valve was set to fully open at 14-16 psi then making sure the fuel pressure was at or more than this 14-16 psi assured enough flow to match that circuit and therefore the VP should remain happy(ier) with enough fuel supply to keep it lubricated AND cool. The same goes for the reason of that small return hole. Without fully understanding the complete function of the VP we can only speculate as to why the diameter size. There are three pressure areas to the VP. Low, middle, and high pressure. We can’t seem to figure out what area the return flows from.....but we do know that it’s not directly connected to the inlet as one would presume because of the common picture of the inlet and outlet being side by side. The fuel has to flow into and around the VP before it exits but we just don’t know how far it makes its way around in there before exiting the excess. Strangely I don’t think there is ANY data which can back this statement with regards to the return flow increasing with the increase in pressure. There's been considerable talk about this along with many schematic diagrams and dissection photos of the VP internals passed around, but until someone actually performs some tests and/or someone from Bosch steps up and releases the iconic VP data sheet, we won’t know. But that doesn’t mean we're not still staying with the concept that fuel pressure needs to remain at no less than 14-16 psi all the time. And we can say that too because we can all attest to what too low of fuel pressure does. A few of you are asking questions which seemingly CANT be answered.....but yet also seem to float around every few years or so. As pointed out, there is NO acknowledged fuel pressure too high for the VP. That doesn’t mean anything either other than we simply dont know because there is no recognized data. Is anything over 20 too high or is it 25 or 30?.....again we DONT know. But in saying that, there is tons of speculation and opinion to fill the informational void. Its just understood that there's no apparent reason to try and cram more fuel pressure through the system than it needs and more so, is all that cramming doing good or is it creating hydraulic heat in the VP or in the fuel pump? All this VP fuel pressure talk must slow down some day since not only has it been hashed out for years but some day most of us are going to move on to newer trucks and then migrate over to the newer model sections of the forum. Hope I didnt make this more convoluted than it already was.....

I'm defending this person for not paying better attention to what he's towing but really with how quiet those class A motorhomes are inside and how powerful the engines can be (especially if its a pusher), I'm sure he didn’t even notice what was going on behind him. Maybe he didn’t have a rear camera, which he should have when towing behind a big RV like that. Whatever the case, its the other folks on the road who should be giving the helpful notice that something’s wrong.....not ridiculing. I cant even begin to count how many people I tell on the road that they have a flat (or going flat) tire on their car or trailer. Its just common courtesy. When towing with my truck, I'd never "feel" a flat tire as the engine just powers unaffected through the additional drag. The last time I noticed my old TT with a flat was only because my boost gauge went up 2 psi and I thought that was strange enough to pull over, whereby I found a destroyed tire back there. Sure would have been nice to have someone behind me give a heads up that it was going flat before it tore up my trailers side. That’s why I now run a TPMS.

I've always felt (and understood) that mechanical is the most accurate gauge. That of course doesn’t mean all electrical gauges are inaccurate and that all mechanical gauges are superior either. I think that accuracy verses inaccuracy is going to come down to the gauge manufacture quality over more than type. I had a high quality electrical fuel pressure gauge for years and then when it finally failed (as do most electric fuel pressure gauges because of sender failures) I chose to go mechanical rather than replace the electrical. I found that the mechanical gauge was more accurate than the electrical gauge. As for running fuel into the cab. That seems to be personal preference but in saying that, I also think its illegal to run fuel into the cab. Not a big deal unless you care about strictly following the laws or if you happen to be in an accident that results in a fire. I used an isolator and it works fine. I think isolators get a bad rap because most of the time they're install incorrectly.

I believe there are a few different fully synthetic PS fluids out there. I happen to run across a quart of Redline when I did mine. And a quart was the perfect amount to allow one flush and then a refill. As for the brakes, do you have rear drums? If so its completely common for them to be grabby first thing when the weather has any amount of moisture. After a couple taps of the pedal they calm right down.

The power steering and brakes work wonders better when using a good quality full synthetic PS fluid. Not to mention PS fluid is the most neglected fluid in a vehicle next to brake fluid. Plus these hydrostatic systems build a lot of heat which will degrade regular PS fluid and cause growning noises and poor steering/brake performance over time. This problem is exagerated even more in the cold climates. Get a quart of full synthetic PS fluid and change out the resevoir twice to get all the old crud out and you'll notice a difference. And I notice my fuel pressures doing the same. Cold weather will cause higher fuel pressures and hot weather will cause lower fuel pressures. But.....not right away. When I first start up in the winter the FP is lower and then will rise to a high when everything is warmed up, but when in the summer when I start up the FP is higher and will drop to a lesser pressure when everythings warmed up.

The thermocouple reacts to the differences in temperature by sending electrical signals to the gauge. The gauge then deciphers those signals and turns it into something you can understand. If you're totally stumpted then simply google how a thermocouple works and I'm sure there's ample website which can explain it in simple form.