Attention: TDR Forum Junkies 
Steve St.Laurent
Staff Alumni
Info from Blue Chip
Guys, I recently received in the mail a paper from Chip Fisher of Blue Chip Diesel Performance titled "Bosch VP44 injection pump failures explained". I'm going to see if I can get permission from him to post the entire thing here on the forums. I'll a couple of excerpts in here now though. They have torn down a number of failed pumps to find the cause for failure.
At the top of their list is bad lift pumps which starve the pump for fuel and the rotor siezes due to lack of lubrication. They also mention (this is what I've heard from several performance vendors) that the pumps many times die under deceleration, not full throttle. The VP44 shuts off ALL fuel on deceleration which none of the other Bosch pumps do. That starves the rotor and distributor for fuel and lubrication.
Here's the one that speaks to what you guys are talking about:
"The reason any aftermarket device that hooks up to the solenoid wire is blamed for failure is that the failure 99 times out of 100 (honest numbers here) the pump fails within 20 minutes of running with power enhancement. The reason this happens is because the fuel solenoid is held closed longer, therefore using more length of the slot in the rotor. The slot in the rotor overlaps a hole in the distributor to allow for different timing and amounts of fuel to be delivered to the injector and when the solenoid holds the bypass solenoid closed longer, then the high "pop off" pressure is still there when the middle of the slot overlaps the hole. The middle of the slot is the weakest area and therefore deflects, interferes and seizes. Pump failure with fuel enhancement devices is not CAUSED by the enhancement device, but PRECIPITATED by the device. WE think this is a "glass half full" scenario rather than a "glass half empty" one, because the potential, eventual failure can be determined within controllable parameters, namely on the test run at higher power, close to home or the local dealer. The other side of the coin is, honestly, if your truck is still running 20 minutes after the installation you have a 99% chance your pump will last forever. Adding a power enhancement device that hooks to the solenoid wire can give you peace of mind that you can depend on the pump. The worst case scenario here is that the replacement pump may not be any more dependable than the first one. I know of a dealer that had to put three pumps on a 2000 truck to get it delivered to the customer! The good news is that we are seeing less and less pump failures out there; we know there have been at least three changes to the pump and hopefully they are all for the better and they are getting more reliable. "
INTERESTING info, huh? This seems consistent with what we've seen here on the forums. Like I said I'll try to get permission to post the entire paper on here. BTW, I'm at 78,000 miles now and have had a Powermax on my truck since 28,000 miles, and drove for about 20,000 of those miles with a BAD lift pump! IMO, everyone should have a fuel pressure gauge on their 24v trucks.
Guys, I recently received in the mail a paper from Chip Fisher of Blue Chip Diesel Performance titled "Bosch VP44 injection pump failures explained". I'm going to see if I can get permission from him to post the entire thing here on the forums. I'll a couple of excerpts in here now though. They have torn down a number of failed pumps to find the cause for failure.
At the top of their list is bad lift pumps which starve the pump for fuel and the rotor siezes due to lack of lubrication. They also mention (this is what I've heard from several performance vendors) that the pumps many times die under deceleration, not full throttle. The VP44 shuts off ALL fuel on deceleration which none of the other Bosch pumps do. That starves the rotor and distributor for fuel and lubrication.
Here's the one that speaks to what you guys are talking about:
"The reason any aftermarket device that hooks up to the solenoid wire is blamed for failure is that the failure 99 times out of 100 (honest numbers here) the pump fails within 20 minutes of running with power enhancement. The reason this happens is because the fuel solenoid is held closed longer, therefore using more length of the slot in the rotor. The slot in the rotor overlaps a hole in the distributor to allow for different timing and amounts of fuel to be delivered to the injector and when the solenoid holds the bypass solenoid closed longer, then the high "pop off" pressure is still there when the middle of the slot overlaps the hole. The middle of the slot is the weakest area and therefore deflects, interferes and seizes. Pump failure with fuel enhancement devices is not CAUSED by the enhancement device, but PRECIPITATED by the device. WE think this is a "glass half full" scenario rather than a "glass half empty" one, because the potential, eventual failure can be determined within controllable parameters, namely on the test run at higher power, close to home or the local dealer. The other side of the coin is, honestly, if your truck is still running 20 minutes after the installation you have a 99% chance your pump will last forever. Adding a power enhancement device that hooks to the solenoid wire can give you peace of mind that you can depend on the pump. The worst case scenario here is that the replacement pump may not be any more dependable than the first one. I know of a dealer that had to put three pumps on a 2000 truck to get it delivered to the customer! The good news is that we are seeing less and less pump failures out there; we know there have been at least three changes to the pump and hopefully they are all for the better and they are getting more reliable. "
INTERESTING info, huh? This seems consistent with what we've seen here on the forums. Like I said I'll try to get permission to post the entire paper on here. BTW, I'm at 78,000 miles now and have had a Powermax on my truck since 28,000 miles, and drove for about 20,000 of those miles with a BAD lift pump! IMO, everyone should have a fuel pressure gauge on their 24v trucks.
- It isnt stock any more, so now I'll have a little more time to read whats on the back of your canopy... 
