This information I am pasting down here is not mine. I got this from VP44 Diagnostic www.BlueChipDiesel.com
I heard they have the top of the line VP44's for a bargin! They also have very accurate overviews and diagnostics of the VP44 so you do not waste thousands! All credibility goes to BlueChipDiesel.
I feel qualified to help you as I owned a full service performance shop for all Dodge Diesels, and Freightliner and Ford trucks with the ISB engine, from 1993 through 2006, when I became a website only, to specialize in this often misunderstood fuel system. Way back in 1998 when my brother and I received the only US Patent for enhancing fuel delivery for electronically controlled diesel engines, I felt that the research we did then might have made us a bit smarter than most, but I have to admit that the experience I have gained SINCE then has made me a much better teacher. As I still answer the phone every chance I get, I am still learning from all of you, to give me way more REAL WORLD EXPERIENCE than others in the industry. This is why I feel BEST qualified to help you. I am happy to share this knowledge and experience to help you make an accurate diagnosis of your truck’s VP44 fuel system and direct you to purchase the right part the first time. As I learn more I rewrite this amazing document to make it even better, so keep checking the update date so you are assured of the latest and greatest information.
My REAL WORLD experience has allowed me to really fine tune what works and doesn’t work for diagnosing this fuel system. To diagnose this fuel system requires a unique approach and a sense of humor as you can’t just plug in scan tool to get all the RIGHT answers. You likely can’t get what you need from a shop manual either as that was probably written before I acquired all the knowledge and diagnostic experience I have now. The codes that are in the ECM are a help, but in some cases mean nothing unless accompanied by a certain symptom. You only need to read the codes in the ECM as that is the only computer that runs the fuel system. The PCM is for all other systems in the truck. In SOME cases the codes we DON’T get are the most important part of determining an accurate diagnosis. If you follow these diagnostic procedures below you WILL get accurate answers, but not necessarily the answers you like! I am so confident in what I am about to share with you, that I make this promise. If you buy an injection pump from me that I have diagnosed with you over the phone, and it doesn’t fix your problem, I’ll take it back within the first week!
There are six components in the fuel system in a VP44 fueled truck. They are the ECM (Engine Control Module), Fuel Injectors, APPS (Accelerator Pedal Position Sensor), MAP Sensor (also known as a Boost Sensor), Fuel Filter, Lift Pump and finally the VP44 Injection pump. The ECM and OEM Injectors almost never give any problem in my experience. In fact up until 2009 I had never even heard of a bad ECM, even at crazy high mileages, so they didn’t need further consideration. Now that these trucks are getting older, I have to eat these words.The APPS and MAP Sensor rarely are a problem, and can be diagnosed with the info below. The Fuel Filter and the Lift Pump have their own diagnostic page that can be accessed by clicking on the link at the bottom of this page. This leaves the VP44 Injection Pump, which is almost always the cause of drivability issues and symptoms.
In my experience the 216 code is not a “Death Code” as some people say. It only tells you the injection pump can’t attain full timing advance and therefore power, and if this code is the ONLY code and you don’t have any other symptoms, the VP44 does not need to be replaced, and will not put you on the side of the road. If you DO have the 216 code you should check your lift pump pressure UNDER LOAD as lift pump pressure is what moves the timing piston and advances timing, so if lift pump pressure is low, that may be the cause of the 216 code. If lift pump pressure is good, then the code means the housing of the injection pump is worn out, which in itself still isn’t a reason to replace the VP44 either, in my mind. Click on the icon on the bottom of the last page of this section for how to diagnose a lift pump accurately.
If the truck won’t start, AND YOU HAVEN’T OPENED ANY FUEL LINES OR REPLACED THE FUEL FILTER SINCE IT LAST RAN, and you have either or both a 1688 and or a 1689 DTC code, the truck will never start until you replace the injection pump, 99% of the time. If you want to be 100% sure of your diagnosis, follow the “No Start” diagnosis below. These codes indicate either a serious internal mechanical failure, such as a seized rotor, or that the computer on the top of the injection pump is not turning on the high pressure fuel to the injectors. Other circumstances like stray RF (radio interference) can cause false codes and therefore confuse or misdirect an accurate diagnosis, so this is where symptoms have more merit than just codes, when diagnosing this fuel system. Code 1693 only means there is at least one code in the other computer, which is the PCM, which has NOTHING to do with the fuel system related drivability problems. Sometimes automatic transmission issues cause a drivability issue and appear to be a fuel system issue. In this case codes in the ECM and the PCM should be duly noted and COMBINED with the drivability SYMPTOMS and a phone call to me, I can differentiate and diagnose the problem with you.To come up with an accurate diagnosis sometimes, you have to prove all the other components of the fuel system that could cause your unique problem, are indeed good. If you have done that, you have no choice but to condemn the injection pump. This is where a missing code along with a drivability issue, is more important than an existing one!
WHY YOU SHOULD CHECK FUEL SUPPLY FIRST
You may think that low fuel supply pressure will cause many or all drivability problems, but NOT SO with this fuel system. Human nature also makes us want to take the path of least resistance, or lowest out of pocket expense, and try replacing the less expensive components before diagnosing this fuel system correctly. Please know that Lift Pumps have their own problems, but are RARELY the cause of an injection pump failure, or a drivability complaint, contrary to what a lot of people want you to believe.
A weak or failed lift pump or a plugged fuel filter will NOT give any other drivability issues OTHER than a skip, miss or buck at high load/high RPM operation. If you DO experience ONLY these symptoms, replace the fuel filter and if you can’t bleed the system, or if changing the filter doesn’t fix the problem, go to “How to Diagnose a Lift Pump” at the bottom of this page and proceed from there.
You MAY have to do a lift pump diagnosis or replace the fuel filter after you put on a new injection pump because the new injection pump may make more power than the old one, therefore using more fuel, and therefore lowering the fuel delivery pressure to the point that you then have the skip or miss at high rpm/load symptoms. Be sure that you have at least 5 PSI Lift Pump pressure UNDER LOAD at all times, to be sure low lift pump pressure isn’t preventing full power or timing advance, and or causing any harm to the old style diaphragm in the VP44. We strongly suggest installing our “Low Fuel Pressure Warning Kit” to monitor fuel pressure, as a diagnostic tool and a future money saving tool. It will tell you when the restriction in the filter necessitates replacing the filter, which means you will change your filter by restriction rather than the seat of your pants and save replacement filter costs! It will also tell you if the lift pump fails mechanically or electrically. Go to our “Product List” for more info about this inexpensive money saving product.
If you have a late model year 2000 – 2002 truck you can read the codes by turning the ignition switch to the “run” position from the “off” position 3 times within 5 seconds and leave it in the “run” position and stare at the odometer. Write down the information displayed, so you don’t forget it when you call me, and it will help your diagnosis. To be sure the codes are pertinent to the current issue, I recommend that you clear the codes after you first read them, with a good scan tool, such as a DRB III. Then REREAD THE CODES BEFORE YOU START THE ENGINE to be sure they are actually cleared, as some scan tools don’t clear all the codes. Then drive the truck until the problem reappears, and then reread the codes. If there is no new code, that is very valuable information, and if you do have a newly set code, it is most likely relevant to your symptom. You can tell what computer you are reading by the code(s) you get. If it pertains to the engine or fueling, then it is the ECM and if it pertains to the rest of the truck it is the PCM. If you get a 1693 code that only tells you there is a code or codes in the other computer. If you have a 1998-99 or a grumpy 2000, reading codes this way will not work, so you’ll have to read the codes with a scan tool. Most auto parts stores will do this for free for you.
This is THE MOST COMMON DRIVABILITY COMPLAINT and is an intermittent one that happens most often when the truck is hot or working harder, but can occur much less frequently when cold too. My experience tells me that 4 times out of 5 “Dead Pedal” is worse hot, but 1 time in 5 it is worse cold! There are no codes pertaining to “Dead Pedal” that will condemn the computer and therefore the VP44.
This is due to “Lead Free” solder failure, now mandated by the federal Government!
The symptom of “Dead Pedal” is rarely caused by a faulty APPS (Accelerator Pedal Position Sensor) and 90% of the time it is caused by a faulty computer on the top of VP44 injection pump. These numbers are NOT an exaggeration. The easiest way to positively eliminate or condemn the APPS as the cause of the problem is to “scan" or read the ECM (not the PCM) in your truck to check for any codes pertaining to the APPS, such as a 121 or 122. If you DO have either or both of these codes you MAY need an APPS. IF YOU DON’T HAVE EITHER OR BOTH OF THESE CODES, THEN YOU PROBABLY DON’T NEED AN APPS, but to be sure, do this definitive test. Diagnosing an APPS accurately can be done with an ANALOG voltmeter, by monitoring and measuring the signal voltage on the blue wire with a black tracer (on Dodges) coming from the APPS electrical plug. Turn the ignition key to the “on” position and slowly press on the throttle and slowly release it. You should not ever see a jump in voltage. It should go up and down smoothly. If it repeatedly jumps up or down, then replace the APPS. As this sensor can be very intermittent, I strongly suggest you do the following test when driving the truck to prove the APPS is or isn’t the cause of your dead pedal. Extend the signal wire used in the previous test up to the dash of the truck and drive it while watching the voltage on your voltmeter. If you are holding the pedal still and the voltage drops when the engine drops power, you need an APPS. If the voltage stays the same and the power drops, you need an injection pump!
IF YOU DON’T NEED AN APPS, AND YOU HAVE DEAD PEDAL SYMPTOMS, YOU FOR SURE NEED A VP44!
If you don’t have access to a scan tool or an analog voltmeter, and want to trust my experience, let me explain the difference in symptoms between a bad APPS and a bad computer on the injection pump. A bad APPS usually is just a flat spot at a certain throttle opening, usually 65-70 MPH, and smacking the pedal to the floor a few times, usually clears it up. If pushing the throttle just a bit more makes it take right off, or if going back to a lesser throttle opening makes the engine run fine, then it is most likely a bad APPS. This usually occurs most frequently, but not always, in cold and or wet conditions. If it is caused by the computer on the VP44, the “Dead Pedal” or power drop occurs at ALL throttle positions and power comes back only if you let the pedal go to idle for a brief time to reestablish “Idle Validation”, or push the clutch in, or shut off and restart the engine, or just wait. This kind of "Dead Pedal" happens most often hot or towing, but sometimes when cold.
TRUCK DIES GOING DOWN THE ROAD
Another VP44 failure is when the truck dies driving down the road for no apparent reason, or when you let off the throttle at high RPM, and the engine won’t restart. This is usually a seized rotor in the injection pump and is most common on 1998 and 1999 trucks, or rebuilt pumps that don’t have the upgraded rotor and distributor. The cause of this failure is a poorly "deburred" rotor, according to Bosch. This machining problem has been addressed and apparently solved in later years, with the updated parts we use. If you run any rotary style pump like a VP44 out of fuel at high RPM you CAN seize the rotor because it runs out of lubrication! This symptom can also be due to contaminated fuel and related corrosion on internal parts of the pump, or an electrical failure of the computer on top of the VP44.
TO MAKE THE ENGINE START AND IDLE ONLY, YOU DON’T NEED ANY SENSORS OR COMPUTERS OR ELECTRIC LIFT PUMP. YOU ONLY NEED 12 VOLT POWER, GROUND, AND FUEL TO THE VP44.
NO START – TEST #1 FUEL SUPPLY TEST
If the fuel gauge reads 1/8 – 1/4 of a tank, put a few gallons in the tank and bleed the fuel system. I say this because of the famous Dodge fuel tank sender problem. Your gauge may be out of calibration for the first time and the tank is actually empty. In this situation air AND fuel is what you are trying to start the engine with! Pressure indicators don’t know the difference between air and fuel pressure, so you may falsely think all is OK. You will be very glad you did this if your truck runs again and you don’t need an injection pump!
If the engine WAS running BEFORE you CHANGED THE FUEL FILTER OR OPENED A FUEL LINE, AND IT HASN’T STARTED SINCE, or, it started and stalled after doing this, AND IT WON’T BLEED and restart, and you can hear the lift pump running, but it won’t fill the filter bowl, you most likely have a bad electric lift pump. Please remember when you are doing this diagnosis that the ECM turns on the electrical power to the electric lift pump only for 4 seconds when the key is in the “on” or “run” position. When the ECM sees the “start” signal from the ignition switch it runs the pump for 25 seconds, and when it sees idle RPM it runs continuously. If the electric lift pump doesn’t come on, or doesn’t pump fuel into the filter bowl when you click the key to the “start” and release it to the “run” position, you can bleed the system to get fuel to the VP44 and get the engine to run again, by pressurizing the fuel tank with air pressure, or diagnosing the electric lift pump. The reason this strange scenario happens, is because there is a mechanical lift pump built into the VP44 which works fine UNTIL air gets into the system. This explains why VP44 fueled engines don’t die on the side of the road when the electric lift pump fails.
NO START – TEST #2 ELECTRICAL TEST
The next no start test procedure is to test the electrical wiring and verify that there is battery voltage getting to the VP44 with the key in the “run” AND ”start” position. Remove the big plug on the back of the injection pump by wiggling the plug with your right hand pulling toward the firewall and the left hand pulling the indented locking tab toward the fender. When you have the plug in your hand, hold it so it looks like a smiley face, with six pins below the smile and three pins above. Using a test light or voltmeter, verify battery voltage on the bottom right pin (pin #7, which is a red wire with a light green tracer) during both “run” and “start” key functions and verify the ground on the bottom left pin (pin#6, which is a black wire with a tan tracer) by doing a voltage test at the positive battery terminal with the ground lead of the test light or voltmeter on pin 6. Use only pin positions, not wire color, if diagnosing a Ford or Freightliner. If you don’t have power at the plug, research the voltage supply to it. Is the fuse in the PDC (Power Distribution Center, aka fuse box under the hood) for the fuel system OK? If it is, then swap the fuel system relay with the one for the horn. If you have battery voltage on pin #7 in both key positions, and a known good ground on pin 6, cut the black tape off the VP44 plug harness to access the wires going into the plug and reinstall plug. On Dodges find the light blue wire with a red tracer (pin #5) and verify that there is NOT battery voltage there during either the “run” or the “start” functions of the ignition switch, WITH THE PLUG PLUGGED IN. The ONLY time there should be battery voltage on pin 5, is for about three seconds after turning the key to the “off” position. If there is battery voltage there at any other time, the engine is being told to not start or run by a pissed off ECM. This test is accurate 99% of the time in my experience. It is not unusual and OK to see low voltage, like .2 -.4 volts at pin 5. The important thing here is to NOT have battery voltage here, and if you do have it there at the wrong times, I have found cutting that wire and running the truck forever that way causes no harm!
NO START TEST #3 HOT WIRE TEST - THE BEST TEST
If you want to be 100% sure it is the pump causing the no start , and not a pissed off ECM or “BUSS” wiring issue to the VP44, follow these next directions exactly, to be sure of not damaging a possibly good pump. This test POSITIVELY eliminates the possibility of overlooking an electrical problem that could affect the start or run function of the VP44, as long as you have verified fuel delivery to the injection pump. Remove the electrical plug at the back of the injection pump and hot wire the pins on the pump as follows. Get two wires long enough to reach from the battery to the VP44. Install an INSULATED ¼ inch female spade connector onto one end of each wire. Connect one INSULATED connector to pin 7 on the pump, which is the pin on the BOTTOM row of the socket on the injection pump, closest to the engine, to preferably fused (10 amp is fine) positive battery power in the PDC (Fuse box under the hood), or directly to the positive battery terminal if you like to take risks!.
Connect the other INSULATED connector to the pin directly above the previous connection, the top row of pins, the one closest to the engine, and attach the other end to battery ground. Now try to start the engine and if it doesn’t start, you absolutely positively 100% need an injection pump! If the engine starts this way but not with the big plug installed on the pump, you know there is something in the 12 volt wiring or buss wiring to the ECM causing the engine to not start. Call me for help if this is the case.
IF YOU HAVE FUEL, POWER AND GROUND, PROVEN BY THE ABOVE TESTS AND STILL HAVE NO START, YOU NEED AN INJECTION PUMP!
If you still want more proof that you need an injection pump after you have proven that you do indeed have electrical power, ground, and fuel to the injection pump, loosen three injector lines at the valve cover. Crank the engine a few times for 30 seconds each time, and if high pressure fuel only comes out of one line or none of the lines, this indicates either a seized rotor, or a stuck fuel solenoid pintle valve. To start the engine you need high pressure FUEL delivery, AND NOT AIR, to at least three of the injectors, NOT just lift pump pressure. To determine if it is or is not HIGH pressure, look for a puddle on the ground after 60 seconds of cranking. No puddle, no high pressure. We proved that you cannot put this pump in a hydraulic lock as the rotor turns, so therefore fuel, low or high pressure, HAS to come out of one injection line even if the rotor is not turning. If high pressure fuel doesn’t come out of any of the open lines, the rotor may be stuck or seized at a closed line. If the rotor IS turning, therefore not seized, and the solenoid pintle valve is stuck in the open position, or the pistons are stuck compressed in the rotor, due to fuel contamination or corrosion, you won’t get high pressure fuel out of any line and the engine will NOT run. If you don’t have high enough pressure to pop off the injectors the engine can’t start. If you have only a feeble fuel flow, this is due to having only lift pump pressure moving fuel through the lines. This injection pump failure is either caused by an electrical issue in the computer or a mechanical issue, neither of which you can fix. Either of these situations confirms that the engine will not start until you replace the VP44, as long as you have done the other tests above.