KATOOM

I'm not saying I'm right and you're wrong rancher but I'm not sure that would be an accurate explanation of the fuel pump. The amount of volume from the fuel pump cant be more than the head pressure can supply. Yet the amount of pressure from the fuel pump and in the lines will be directly related to the amount of fuel volume consumed by the engine in relation to the pressure generated. If the engine has enough fueling then you can pull the fuel pressure in the lines down considerably. That means that the pressure at the pump impeller should decrease as the fuel supply increases. That is unless I have it backwards whereby the fuel volume running through the fuel pump is "X" amount during idle and cruise but when the fuel demand increases then so does the fuel volume passing through the pump and therefor the pump is pumping at or close to maximum pump volume which may cause impeller cavitation. Notice I use the head scratchy smile a lot.....

Good points guys but no, there's no vacuum in the tank. Matter of fact I actually installed a filter on the vent just to assure that its never plugged up with junk. Its clean. And I would certainly consider cavitation except I would "think" that cavitation would be the at its highest probability during idle since thats when the pump is pumping the highest psi in relation to the amount of fuel used. Why would the pump impeller experience cavitation when more fuel is being demanded? Since the fuels volume and pressure is under constant regulation at all times, wouldn't more throttle actually decrease the effort placed on the pump? On a side note, I've dealt with cavitation quite a bit since I have a high powered v-drive boat. When you place hundreds of ponies on a propeller trying to shove a 3000 pound hull up out of the water from a stand still, its takes the right quality prop to not froth up in a mass of bubbles.

But wouldn't you think it would be more likely to cavitation when the VP isnt using as much fuel.....not when its using the most fuel? Not sure.

I dont think the fuel pressure gauge bobbing has anything to do with sloshing fuel because it doesn't matter if my tank is full to the top or not.....it still does it based on throttle position. The way the needle bobbing acts, I think its related to the fuel pump regulator ball skipping around. I know that the air separation fuel pump regulators recirculate back to the fuel tank as where the pumps like the Raptor dont but that said, there still is fuel passing through the overflow valve all the time so you'd think it wouldn't be a problem for those pumps without recirculating regulators. Does anyone have the bobbing who have an Airdog or FASS pump?

You're right. The pulses are what generally takes out the senders but when I installed the DD gauge it was one of the ONLY electrical gauge manufactures which was proving reliable against the pulses. And I installed a snubber in the line too. Other electrical gauge manufacturers weren't lasting very long at all. So after 8 years of good service, the sender did finally quit and when I talked to DD they said that those older senders I had couldn't stand up to the new recipe in the ULSD which causes the fuel to wick internally inside the sender. The new updated senders were solid state.....and very expensive. And yes, it may be the isolator. I have a test port pre the isolator so I think its high time I make some test runs with the fuel pressure test gauge held in the cab while driving. That way I can isolate the isolator and gauge. When I get a chance to do this, I'll post back.

They symptoms have been there for the entire time I've had the ISSPRO mechanical gauge on there. If it is related to the Raptors regulator then I dont think the DD electric gauge would have been able to read the fluctuation that fast which is why I never noticed it before the mechanical gauge. I thought I remember reading that the Raptor fuel pumps did weird things like this but I cant find anything regarding.....

I used to monitor the fuel pressure with an Dakota Digital electric gauge. After 8 years of service the ULSD ate the pressure sender so I replaced the gauge with an ISSPRO mechanical and isolator. Same arrangement just different gauge. Its been on there for about 2 years now but even though it reads quite accurately, it does something odd. At idle the gauge needle is solid around 20 psi and when cruising along down the freeway the gauge is solid at around 18 psi. Then all of a sudden the needle will "bob" down a couple psi and quickly return. Its a more fluid action as this is a mechanical gauge but is also very random and kinda hard to watch for too. But.....if I'm pulling a trailer and have reason to be hard on the throttle then the "bob" of the needle can become more regular as I'm holding steady heavy on the throttle. Still, its only a "bob" of about 2-3 psi but its a strange action and the only way I can describe the way it moves would be like watching a fishing pole bobbin dip under water when a small fish is tasting the bait. In saying all that, I have yet to take the tester gauge out for a drive and see if the test gauge does the same thing but I figured I'd ask around first and see if anyone has experienced the same. My tester gauge drips and I need to fix it before I'm holding it in the cab..... I really cant imagine why or what the bobbing action could be other than maybe the Raptor 100 (older better unit) has a regulator which has trouble regulating a smooth amount of fuel pressure when the fuel volume demand increases.

Since I never tow anything other than the rowboat In 5th gear..........running down the freeway at around 70 mph in 5th for more than 15 miles or so will generally have the transmission running around 140*-175* depending on the ambient temperature.

Without a doubt the Fastcoolers helped. Yes the added capacity helps the overall temp but the Fastcoolers offer good heat dissipation since they're hollow aluminum and the main transmission body is not. Although the biggest difference I found was after installing the exhaust blanket as it became apparent that the hot 500*-1000* exhaust pipe was transferring some of that radiant heat over to the neighboring transmission. The tranny temps dropped around 40* after the blankets. I can tow a 14k 5th wheel down the freeway in 100* weather in 4th gear and the tranny will stay around 150*-160*. The biggest heat generator in the tranny is when I have to run in 3rd or 2nd gear because the ratio reduction running through the gears heats the oil.

I monitor the temperatures in both my differential and my 5 speed. I ran out of gauge locations so I used the cubby hole and a Westach dual temp gauge. I installed Fastcoolers on the 5 speed and an exhaust blanket where the exhaust pipe runs along the tranny and transfer case. I also installed a Mag-hytec on the 80. My findings over this project were quite interesting too..... Mag-hytec with temperature sensor coming out the top. This is the old stock exhaust. Now there's a 4" with two blankets end to end. New exhaust. The blankets are hard to see up there but they're about 6 feet long combined from one end to the other. Fastcoolers Tranny temp sensor in Fastcoolers. Westach dual temp gauge in cubby hole.

I think thats a logical approach Mike. It could merely be the combination of all that it takes to crank over this iron slug is too great or maybe the wiring to the VP is too light weight.

I want to believe that the PSG issue has something to do with "heat cycles" but if this was true then there would be direct correlation with failures and the trucks running in hot climates verses those which are driven in the more temperate areas. Which is why I'm feeling this is merely a "starting cycle" voltage issue altogether. But.....I also hope it has nothing to do with heat cycles just so I feel more comfortable driving my truck anywhere in the summer.....

rancherman, I think thats a logical concept. I'm not electrically savvy to understand the if, ands, and whats, but it would it seem possible to measure the "heat" generated at the transistor if you could measure the load.

That statement could be viewed from many angles.....

Added grounds bring up a concern. What are you guys referring to as "added grounds"? I've added a few electronic devices (guages, sub, exhaust brake solenoid, 2 lo solenoid) but my grounds are always specific to the closest body panel I can reach from the device and I never tap into the negative post. I have shared a ground just to keep from drilling another hole somewhere but I didnt ever think that was bad. I'm pretty anal about keeping everything looking as factory as possible so I dont have wires dangling around or sprawled across the engine like some of the spaghetti wiring jobs we've all seen. Also, is there a relation to alternator AC leakage and the amperage output? Meaning, will a more amperage alternator create more AC than a lower amp version? Or is the total AC noise related to the charge of the alternator no matter its capability? Again, when I tested my alternator for AC noise the numbers were .020-.021 at idle and with the air condition and blower on high.

You're kinda bumming me out Ed..... I may live in denial but I still want to believe that there's quality in this country. You may just have to dig a little deeper to find it since most capitalistic people will take, or have to take in order to remain in business, the cheaper Hecho path.

Ya, I agree that alternator AC noise "could" be an issue but at this point I'm not convinced enough to rule out simple power surges during start cycles and the heat generated during those spikes of juice. I'm not sure there's reason to think all of our alternators are junk. Look.....if there's anything we know, (and taking it with a grain of salt too) we do know that "heat cycles" are supposedly a recognized issue with the PSG. So obviously it would seem that someone somewhere has deciphered or come up with that there's something going on in the PSG during that moment in time when starting the engine causes the Pb free solder to crystallize. Is it the fact that the PSG is already hot and then the spike of amperage is enough to overheat the solder joints or is starting the truck at any time abuse to the PSG solder? For whatever reason, some VP suppliers will discuss "heat cycles" and some will discuss "start cycles". Are they one in the same and simply a confusion of language? There's those of us who are seriously considering that the heat soaking is a major issue here and I'm not ruling that out. Anyways, when we're talking about start cycles I think its very important to remember this older article: http://www.farmshow.com/view_articles.php?a_id=646 The guy in that article has (had) more miles on his 2000 Dodge Cummins than most people will ever drive every vehicle they've own combined. But more importantly to note in the article is that the truck has gone through many lift pumps and other things.....but NEVER changed the injection pump. Again.....NEVER changed the injection pump. He has some custom built injectors and some unknown HP box claiming the truck makes around 300 hp. Now in knowing this.....and assuming the old guy isnt lying since he has no reason to lie.....you have to consider what hot shot drivers do. They drive and drive a lot of miles and the amount of shut down times in relation to those miles driven compared to any of us daily driver guys is going to be nowhere close to the same. Even you Mike..... You live in an area where you say its an hour or more just to go shopping for the basics. That means most likely your shut down times in relation to the miles driven are going to be a lot different than those daily drive guys as well. Maybe this is why you have 200k on your VP.....and I'm sure how you treat your truck helps too. But nonetheless, its a well worth point to be made.

Well thats just interesting.....and kinda frustrating too. In all honesty I couldn't have been more clear on my intentions and needs from this new clutch.....and what I have and what weight I pull around. My truck is "maybe" making 300 hp currently and I "maybe" installing some 50-60 hp injectors some day down the road. But with all that said, my biggest concern when talking to Valair and SB was that I'm hauling around 14k lbs behind me in the hills and under full throttle conditions. I do NOT want this new clutch to slip, even with those bigger injectors, otherwise I'd be one upset customer. SB said that without a doubt the organic clutch I'm getting will hold 425 hp at the wheels and pull 20k lbs. What can I say to that? SB is a top notch company and I cant imagine why they'd lead me astray since cost wasn't part of the discussion.

Oh I'm sure it not only controls those two solenoids but I'm betting the power surge during the starting process is higher than we think as the transistor acts as a capacitor and "I'm leaning" towards feeling like this is what dictates the start cycles. Take that with a grain of salt too.....

Dont worry Tom..... You're not alone because I'm still a little confused about this myself. So it was explained to me, if the engines HP/torque is not high enough to slip the clutch a specified design amount for the material used during day to day driving then the clutch will be overly grabby and the material will not hold together like its supposed to and get hot. I fully understand why a clutch unnecessarily stronger than the HP generated "and" the weight of a vehicle would cause the clutch to be aggressively grabby, but I still dont understand why it would burn it up. Matter of fact during those conversations, I asked the clutch people if I bought the high rated clutch and simply started off in 2nd gear more often would that do the same thing, and the answer was no. Then I tried to say that this made no sense to me because the way I was looking at it was..... If you take two identical trucks weighing in at around the same weight. Both have the same engine but one makes 300 hp and one makes 500 hp. Under those circumstances then the clutch should see the same wear and slippage upon taking off from a stop. It shouldn't matter if the one engine made almost double the HP since both trucks still weighs the same as the other. But they kept saying no it doesn't work like that. So I dont know.....

I was told that I didn't make the HP for the K/C clutch and it would burn its self up and drive horrible. The one I'm getting is rated to 425 at the tires. I'm lucky if I make 300 right now.....

My clutch is still on its way and UPS is supposed to deliver it on Friday. The 5 speed trucks have a 12.5" clutch with a 1.25" input shaft. The clutch I ordered comes with a new 13" flywheel and clutch but still has the 1.25" input shaft. I could have upgraded to the larger input shaft for another $300 but I have no intentions of making that kinda HP. If I ever get the 50-60 hp injectors I'm wanting then that will be all the power plans I have for this truck. And the current clutch I'm getting is supposed to handle that added power too.

Nice work Ed. I'll be reading up..... On another note, like I mentioned before, there's considerable effort in the European and Spanish folks whereby they've dealt with the PSG and transistor I think way more than we have over here. Matter of a fact, just for sake of the thread, here's a picture of someone who actually tried to shade tree fix the PSG and a link to another foreign thread http://www.forum-auto.com/pole-technique/mecanique-electronique/sujet537674-35.htm where they're experimenting with soldering in the circuits and replacing parts. I cant read the language but if anyone's bilingual then maybe you can make out what they're doing or even if it worked. But back to my "theory" about simple electrical strain or surges placed on the PSG, you'll notice that the high pressure solenoid and the timing solenoid both connect to the PSG right at the transistor. Coincidence?.....not sure. But below is a couple more web pages with some interesting info regarding Pb free solder and how it reacts to heat, contraction, expansion, and surface warping. http://product.tdk.com/en/techjournal/archives/vol05_mlcc/contents06.html I found it interesting but still not understanding why the main failure of the PSG is the transistor.....

Does anyone know if you can remove the PSG cover and replace the screws and still be able to run the engine? I know there's an o-ring seal under there which must be held tight but my understanding is that no electronics are ever bathed in diesel. Having the cover off would make it possible to view the circuitry of the PSG while the engine is running. Not that you'd be able to watch anything as you're cruising down the road but you could certainly try to establish what happens during heat cycles and start up cycles and maybe even detect the temperature of certain portions of the circuit and the transistor.

Maybe you're right Mike. Maybe the updated computers do have better components.....just like the rest of the VP received over the years. Strangely though, I clearly and without a doubt remember Chip telling me a couple years ago that Bosch upgraded to a larger heatsink for better PSG heat dissipation but when asking other (just as reputable) venders they say they've never heard of that. So.....who's right? Well since I've never seen a picture of a VP which doesnt look like any other bazillion VP's I've seen on the internet, I would have to say assume that there's been no heatsink change. But I also agree with you in that there's no reason running temperatures should ever affect the PSG. Even heat cycle temperatures shouldn't cause a problem since anything I find says that the lowest melting temps for tin solder are around no less than 400* F.....and thats on the cold side since optimal solder gun tips run in the 600*-700* range. I'm beginning to think that the "heat cycle" theory is just that.....a theory. Potentially bogus too. Just like the dreaded torn or cracked diaphragm theory which seemingly plagues every VP that lands on the bench of a VP supplier. Especially if its a warranty item. A knee-jerk response we still see it floating around forums like its fact too and is the main cause of all VP problems. Its almost like the FDA is helping Bosch come up with things to tell everyone..... There's a reason the PSG fails. Is it heat or is it surges of electricity? It sure would be nice if we could find out. It only took around 10 years for someone to volunteer a VP core. Maybe it wont take another decade before someone with some serious electronic skills can figure this out. Thats not to say Mike isnt an electronic guru either.