VP44 Injection Pump Failure

One of the most common failures of the VP44 injection pump is the cracking of the stainless steel diaphragm (pictured on the far left) which in turn causes premature & excessive wear on the advance piston. Lack of fuel pressure to the injection pump is the reason for this. The internal supply pump (the item on the far right of the picture) inside the injection pump creates an enormous vacuum which causes the diaphragm to flex, crack & break. Another main failure of the VP44 injection pump is the advance piston (middle item pictured). The piston becomes scored (light colored marks at top & bottom) & sticks in the pump housing which usually sets a P0216 timing advance failure code. This failure can also be contributed to lack of fuel pressure being supplied to the injection pump. In other words, keep your VP44 pump supplied with fuel pressure!!!!!!

Fuel Pressure on 1998.5-2002 Dodge Cummins 24v 5.9L

One of the most important items to check regularly on your Dodge Cummins 24v 5.9L engine is the fuel pressure from the electric fuel supply pump. This is extremely important on the 1998.5-2002 year model vehicles. Failure to keep the VP44 injection pump supplied with the correct amount of fuel pressure will cause the injection pump to fail which can result in a major repair bill. The pressure needs to be no less than 7-8 psi when under a heavy load or hard acceleration condition. New supply pumps (see picture) will usually put out about 14 psi @ idle & then drop to 7-8 psi under a load. Here are a couple different ways to check the fuel pressure on the 1998.5-2002 vehicles. When checking the fuel pressure you need to make sure that you check it before the fuel filter & after the fuel filter. Checking it at these 2 locations will let you know what kind of pressure drop to expect after the fuel filter. On the early 1998.5-1999 year model Dodge Cummins diesels there are 2 brass fittings on top of the fuel filter canister. One fitting is for checking pressure before the filter & one is for checking pressure after the filter. On the 2000-2002 year model vehicles, there is really only 1 fitting in the system that is easy to use & it is located at the inlet of the injection pump. The fitting at the pump has a schrader valve in it so all you need to do is connect a hose with the correct size of fitting on it & start the engine. Fuel pressure test kits are readily available at various internet performance web sites. Monitoring the fuel pressure on the vehicle can be done a couple different ways. One way is to install a warning light that will come on when the fuel pressure drops below 5 psi. Another way is to install a fuel pressure gauge. Depending on how your vehicle is set up, whether or not you have a performance chip, injectors or if your vehicle is stock if you do not check or monitor the fuel pressure you will have to replace the injection pump.

Basic Diesel Engine maintenance

Basic maintenance for your diesel engine is relatively easy. For the early diesel engines ie: 6.2L, 6.9L, 7.3L indirect injected non turbo engines as well as the later model turbocharged & direct injected engines here are some tips. One of the most important items to maintain regularly is the replacement of the fuel filter (s). Changing the fuel filter every 5,ooo miles on systems that have only 1 filter is recommended. If your vehicle has 2 fuel filters, a primary & secondary filter you can go to 7,000 miles before replacing the filters.
It is also recommended that a fuel additive be used in the fuel system to help keep it clean & lubricated. On late model vehicles that have only one fuel filter, adding a primary fuel filter is like taking out an insurance poicy on your fuel system. The better the filtration, the longer the fuel system will operate without premature failure.
The next item which is really the easiest & one of the most important to maintain is changing the engine oil & filter. Engines with & without turbochargers on them must have regular oil & filter changes done. You need to change the engine oil & oil filter every 3,000-4,000 miles to help keep the engine clean & lubricated properly. Changing the engine oil & filter on the late model diesels especially the Ford Powerstroke is extremely critical since the injectors are lubricated & actuated by the oil system. It is recommended that you use Delo 400 with a grade of 15w-40 or equivalent in the newer engines. Make sure you dispose of the used oil & filter properly. Also, do not forget to replace the air filter.
The 3rd item that you need to maintain is the coolant. A 50/50 mixture of clean drinkable water & coolant will usually give freezing protection down to -34 degrees F & it will also give boiling protection to 265 degrees F. On the early diesel engines especially the 6.9L & 7.3L Intenational engines in the Ford pickups there is an additive that should be used in the coolant system to prevent electrolysis from happening.
That is basically all that is required to maintain your diesel engine.