Government regulations. The solder uses inferior tin solder that heat cycles and cracks. Lead based solder is far superior, but not legal.

 

That topic is still up for debate, and let me say why.

Remember, the Cummins VP engines were widely used, not just in Dodge trucks. There were literally hundreds of thousands of them built. Especially during the late 90's and early 2000's, which is why you hear talk about the 53 block so much too since that was a common cast back then. These Cummins engines were used in commercial trucks, like delivery trucks, as well as many other applications, and the failures were certainly NOT limited to the Dodge engines either. So you can imagine the problem this created for Cummins as failing fuel injection pumps were not only angering the consumer world but also shutting down the commercial industry as well.....

Anyways, there was rumor years ago that even though the PSG failure problem was because of some new environmentally friendly lead free solder which was supposedly required during the PSG assembly. Now whether or not that was completely accurate or not (which we believe it was), at some point in time there were people who were after or received remanufactured VP's with what was called "Fedex" computers. There was talk that the number 028 or 029 pumps had/have the tell tale identification too. So what was or is a Fedex computer? Well it was thought that Bosch started building or built some special PSG's specifically for such commercial applications, like Fedex trucks, in order to keep these commercial engines on the road.

Now whether or not these are all wives tale stories, I cant say with complete uncertainty, but I was always under the impression they're true since the sources were generally good.....

 

That's interesting to hear, maybe somebody who has a hundred thousand miles on their VP will chime in and let us know if they have that number on their pump....

 

I've replaced mine twice.
But ultimately, I want a 4x4 version...mine is just 2wd. Starting the search.
Thanks for all the inputs.

 

If you look around places like craigslist.org you can sometimes find them. But just know that they're in fairly high demand so asking prices can be surprisingly high. If you do find one then make sure it hasnt been abused and/or doesnt have all kinds of aftermarket hp goodies on it which would be a tell tail sign.

 

I'm sure mounting the PSG to the pump was not the perfered location. Many times when designing things compromises have to be made. Some of the challenges with this pump design required that the PSG be mounted where it is. Also realize that this pump is fitted on compact cars so there isn't enough room for a full sized traditonal printed circuit board with through hole components. There is a lot going on in that PSG. In 1997 the types of constuction used for the PSG were for tiny throw away things like cell phones and toys so it's a wonder they last for 10 years or more. The engine manufactures wanted plug and play too so they wouldn't have elaborate calibration issues.

There is a lot of heat to be disapated by the fuel solenoid driver circuits. The solenoid has current peaks of 20 amps and 4-5 amps once seated. So a large heatsink is requ ired. instead Bosch used the fuel flow under the PSG for cooling to save space.

The timing tone wheel and angel posistion sensor are also very compact and produces a very weak signal. A larger more robust positon sensing system would have made a larger and c omplicated pump. The signals from the timer sensor and the fuel solenoid feedback signals are easily lost in the electrically noisy automotive enviroment so once again the PSG needed to be mounted close to the signal sources.

Trying to open and close an electo-mechanical valve a 150 times a second is not an easy task. so the driver has to turn on a certain amount of time before the firing event because of plunger inertia. This time of course changes with RPM, battery voltage, and fuel temperature. The test bench ball parks these delays and stores them in tabels in the PSG. The PSG also has the ability to adapt and fine tune its self from the solenoid current monitors. Thats just speculation based on some of my observations. I've also noticed that the solenoid will bounce several times if slammed shut so the driver hits it hard to start moving then backs off just before seating the valve.

 

I'm totally intrigued by you PSG observations. Generally being the the culprit for issues on these pumps, it would seem like the best method for lessening PSG issues would be to install a reliable circuit board and relocate it from the pump altogether.