Getting Longer Life For Your VP44 Diesel Injection Pump
After many years of observing and experimenting with the VP44 fuel system, we at Blue Chip Diesel are convinced that the operating environment of the vehicle and how additional horsepower is made inevitably determines the life expectancy of a VP44. That said, there are several factors that can help in increasing that life expectancy.
1. Temperature of the Pump
The biggest factor in the success of a VP44 pump is that of temperature. Trucks that operate in hotter parts of the country tend to have more problems than those in cooler regions, the worst case scenario for these injection pumps is to be mounted on an engine that gets shut off multiple times in a day's work. Additionally, trucks that make more horsepower through the use of a programmer type power enhancement device tend to have more problems. The reason for this is because the more horsepower you make with a "programmer," a performance device that connects either temporarily or permanently to the data port under the dash, the hotter the injection pump becomes. A programmer enhancing fuel holds the fuel solenoid closed longer, increasing the duty cycle with commands from the software in the computer, which creates more heat on the injection pump computer board.
The aerospace industry, among many others, has made much mention of how the federally mandated lead free solder has drastically reduced the life expectancy of circuit boards that have to perform in high heat applications. "Fueling Boxes," such as our "FMS," dissipate the increased heat from the increased solenoid duty cycle in the box instead of on the computer board in the injection pump. We are convinced that the best thing you can do to protect the life of your VP44 diesel injection pump is to do your best to reduce the number of heat cycles the vehicle goes through.
We have exhausted many options trying to figure out a way to keep the computer cool, from fans, cooling plates, remote mounting of the computer, to insulating the computer, etc., etc., all of which were not a viable solution to the heat problem for one reason or another. We were not really surprised to figure out that the hottest these pumps get is 20 minutes after the engine is shut off, because of heat soak from the latent heat in the engine.
We thought this issue could be a simple fix. We would just make a control box that ran the lift pump for half an hour after shutting down the engine. During our research and development for this product we were really surprised to learn that there is no return fuel and therefore no cooling effect for the injection pump unless the shaft of it is turning! That stopped us dead in our tracks, so our best advice now is to use the best lift pump you can find, to provide the most flow and therefore the best job of cooling while the engine is running to get the best life out of injection pumps. The common sense theory here is the cooler the pump is when you shut off the engine the less hot it gets from heat soak.
Here’s our reasoning for this. If you pump fuel through a supply line at 5 PSI, which is a normal/reasonable operating pressure for the OEM Carter lift pump, a certain volume will flow, creating a certain amount of cooling for the computer. If you pump fuel through the same size line at 15 PSI, more fuel will flow and therefore offer more cooling, right??? So, our idea was to use 15 PSI or so, all the time to see if repeat failures were diminished or eliminated. We are convinced from our experience and testing that this works to some degree, depending on operating environment, and therefore worth sharing with the world. We have done extensive tests to prove that 15 psi is not too much for other components in the injection pump to deal with.
We now offer a REALLY good lift pump that puts out a constant 15 psi all the time, so the injection pump will be as cool as it can be when shut off. This pump is the tried and true and well respected Air Dog Raptor Pump. If you are contemplating an upgrade to a better lift pump and have the REALLY weak dealer installed lift pump in the fuel tank, it can and should be removed from the system. It is not a difficult removal process. Remove the fuel tank sending unit assembly, cut off the electrical wires going to the pump and cut the motor off the plastic pickup pipe with a hacksaw. Replace what you cut off with an appropriate length of REINFORCED rubber fuel hose. Our recommendation is to NOT reuse the sock at the bottom of the tube, as this can only bring trouble later on. Why not find the crap in the fuel filter, rather than having to remove the tank later on to find the sock plugged? This is another good reason to use the FRRP, as it doesn’t care about crap going through it like a vane pump does.
2. Running an Additive
One thing to remember, is that these pumps were designed to run on fuel that is no longer available. Anyone who remembers using diesel to wash parts will remember that the fuel would stay around until you stepped in it or until you disposed of it. Nowadays, fuel left out will evaporate because it is thinner, not as oily, and the lubrication is significantly down. Using an additive will increase the specific gravity of the fuel, enabling it to conduct the heat, and increase the lubricity for working components to work and function properly.
3. Higher Volume Lift Pumps
Most OEM lift pumps are rated at 40 gallons per hour. Using an after-market lift pump, (e.g. 100 gallons an hour) can provide 2 1/2 times the volume/flow to help maintain fuel levels in the cavity of the pump to maximize cooling and help prevent any fuel starvation problems.
For any other questions on ways to improve your pump's longevity, feel free to shoot us a note or give us a call.