Engine/Transmission (1998.5 - 2002) VP 44 failed today

[Turbo Terry]

15000 miles 2 years and no hard pulling since the last replacement. This is with a RASP 14 lbs. at idle 20 going down the road. Cunmmins tried to tell me my pressure was to high thats what killed the pump BULL**** first the stupid lift pumps(3)went bad(low pressure) and killed the last vp now the pressure is to high and killed this vp or they said it could be the VanAken box. They are just guessing with my money Started to say what a bunch of fools but I,m the fool for giving them my money. Anyway this pump is toast. Rant over Thanks So whats killing these pumps? 1999 275 RV va boost module and a RASP Does't the RASP dump the fuel back in to the tank after 17 lbs. pressure?

 

[BradyWilliams]

We see many different failures with the VP44 pump. First is of course is a broken diaphram or diaphram seals leaking. This is usually caused by low supply pressure or the seals being old, flat and hard. The electronics in the pump can fail due to fueling boxes, AC voltage from a bad alternator can be a contributor to bad eletronic components, the fueling solenoid wire going to ground, excessive engine heat may also cause early failure. Contaminated fuel including water, dirt, algae or gasoline will cause failure. Filtered but not processed french fry oil will cause pump failure also. We have seen some VP44 pumps that come in, look like they have been at the bottom of the ocean inside, which is caused by contamination in the worst of cases. The support bracket being broken or not installed can cause the mounting bolts to loosen and causing housing damage or even the housing to break. We have seen pumps that have had fueling boxes stacked cause the shoes rollers and camring fail due to eccesive load. And yes parts can be defective and fail, but Bosch has had much history of making very good parts. We always use the most updated parts when we build our VP44 pumps. Bosch has had to update some parts in the VP44 like pump housings, PSG's, advance pistons and diaphams. Hope this helps! Thanks, Brady

 

[Graphic man]

IMO. . 20psi is to high, i run 13 at idle and 14-15 at WOT..... the RASP with return what ever your REG. is set to return... . there are lots of guys running high psi and have never had a problem... i am at 180,000 miles on the org. Vp44.



... if it were me i would bring it down to around 14-15 at WOT







just my $0. 02



Scott

 

[MShea]

Isn't true that the VP44 internally relieves at 21psi?

Mike

 

[BradyWilliams]

The actual supply pressure should be 13. 5psi under load and 15-16psi would be ok at idle. 20=21psi will not make too much problem at idle. The problem with raising the pressure more and more is it changes the calibration of the pump. The biggest problem with excesive supply pressure is that the VP44 runs transfer pressure up to 100-120psi at full load. Any additional supply pressure increase will result in more transfer pressure over the 100-120psi. Since the VP44 is a rotory pump the head and rotor will seize or break due to too much hydraulic side loading. The seizure point from too much transfer pressure would be in the 150=160 range. Stuck trans. pressure regulator piston can cause high pressure and seizure. This is caused by contamination. If you want exact numbers for pressure I can get those while at work. If I can get off the phone. Thanks, Brady

 

[Turbo Terry]

I have a RASP the pressure starts at 13-14 idle and go up to 19-20. Rasps only go up as rpm increase.

 

[rweis]

Brett,



f you can get the phone out of your ear, lol, yes, I for one would be interested in what lp feed pressures would cause the internal transfer pressures to go over 120 psi, or certainly what lp feed pressures would cause the danger zone of internal transfer pressures going into the 150 - 160 psi range.



You had mentioned OUAT (once upon a time) that 13. 5 idle to about +3 was about as far as you want to go. The discussion at that thread was on the diaphram and the flexing of the diaphram and the mm of flex and it's seals etc.



Thanks in advance for the info.



Bob Weis



Opps, you are right, please accept my appolligies

 

[Cummins724]

Brett,



f you can get the phone out of your ear, lol, yes, I for one would be interested in what lp feed pressures would cause the internal transfer pressures to go over 120 psi, or certainly what lp feed pressures would cause the danger zone of internal transfer pressures going into the 150 - 160 psi range.



You had mentioned OUAT (once upon a time) that 13. 5 idle to about +3 was about as far as you want to go. The discussion at that thread was on the diaphram and the flexing of the diaphram and the mm of flex and it's seals etc.



Thanks in advance for the info.



Bob Weis

I believe that was the Mac Daddy himself..... Brady that is posting. He signed off as Brady.

 

[Turbo Terry]

So I cut my spring down some(3 times) the first two showed no pressure change. Then on the 3rd cut I got to 9. 5 at idle and 15. 5 at 2000 rpm and 18. 5 at 2400 rpm which seemed ok as most of the driving is at or below 2000 rpm. Then decided to trim a wee bit more(4th time) and my pressue went back up. This is with a mechanical gauge and a dash mount gauge showing the same reading. So what is happening????

 

[Turbo Terry]

^^^^^^^^^^^^^ ?

 

[rweis]

I did sort of the same thing with the spring.



I made one cut, but instead of cutting again I bent the place I cut the first time into a much more flat contour parallel to the surface that the end of the spring sits on. I think the differences in pressures is because of how the spring point that was cut is sitting on the body of the valve. I think it may not sit the same way exactely every time.



Bob weis

 

[Turbo Terry]

Finally got the spring cut the way I wanted. 12lbs idle 14. 5 full tilt boogie. Took that regulator off and on so many times I could do it standing on my head while I was sleeping. Thanks for you alls help.