If I crank it tons of fuel sprays out. After it had been sitting for about ~12 hours I opened all of the lines and I got maybe 3 drops of fuel out of all of them together. I even thought maybe I could put a clamp on the return fuel line after it had been running so the fuel couldn't go back to the tank, but that didn't help either.

 

WD40 will work to start it, but this method will only prove that it is a fuel delivery problem. It will not tell you why. No crank sensor will also give you a no start and no fuel.

 

unfortunately my manual doesn't cover anything older than 2001 ..... but if the crank sensor is bad would it run at all? Ill have to do some research on that

 

Crank sensors (or any sensor) can fail intermittently, usually when they get hot. From your description, your truck is starting cold and running fine until you shut it off and let it hot soak. After a 20-30 minute hot soak the truck will not start. Is that correct? and if so, will it start if you let it sit over night? If it will start after sitting over night then it is not an air leak.

 

No, just the opposite. It will not start cold until about 15 minutes of cranking, rough idleing, dieing, and then out of nowhere it starts right up and runs fine. Once you have it started it will start and run fine until you let it sit for a while.

 

HARD START HOT OR COLD

Other complaints with the VP44 trucks are frequent OR intermittent hard start hot or hard start cold. If, after either of these problems are observed, when the engine starts does the engine run rough for a few seconds and then clear up and run smooth, or does it immediately run smoothly? If the truck runs rough for a while this indicates a fuel delivery problem, such as fuel drainback or air getting into the fuel supply line. If you have rough running briefly after start you probably do NOT have an injection pump issue.

If the truck runs instantly perfectly when it finally starts or shows white smoke on start up, your problem is a faulty computer on the top of the injection pump. This component cannot be replaced in the field as it has to be programmed and calibrated to the mechanical part of the VP44 on the fancy test stand made just for VP44 pumps. You have to buy a replacement VP44 injection pump to correct this problem.

 

The APPS and Crankshaft Sensor can be diagnosed accurately by reading the codes in the ECM. These components always set a DTC code if they fail for just a second. Last but not least, and almost always the source of the problem, is the VP44 Injection Pump.

 

also too high lp pressure can cause hard start issues
VP44 pumps are designed to operate at no more than 14 psi input pressure.... some people are using higher lp pressures with no problems, I for one had a system on my truck that put out 21 psi at an idle, currently I have 13
a suggestion : check fuel pressure with engine off , key on, pump running. if it's more than 15 psi that could be the problem

 

--------------------------------------------------------------------------------

easy check for high fuel pressure is un plug lift pump. if it starts easy, high pressure is the problem.

easy fix, install a 10 amp normally closed rely ( radio shack )in lift pump circuit and power the relay with starter solenoid lead.
the relay opens when cranking turning the lift pump off.

 

The engine either
1. Starts, runs rough with dead peddle, then dies 5 seconds later
2. Starts, runs rough with dead peddle and stays idle(VERY lopey)
3. Starts, runs perfect with absolutely no issues.

Usually it happens in that order, too. I have kinda figured out that if I key the ignition on letting the LP run, then turn key off, then turn key on and go straight to start without waiting for the LP to engage it will usually start, idle rough and stay idle. When I can get it to do that I usually leave it running like that for ~10 minutes, shut it off for a minute and when I restart it, it usually starts and runs perfect. I'm assuming it's because leaving it idle like that for so long gets the air out of the system and allows it to start and run perfect on the next fire.

What I thought was strange is once it starts and runs rough, no matter how long it idles for, it will stay that way until it's shut down and restarted again. It never clears up unless it's restarted. Same thing when it runs perfectly, it never has an issue once it's started and running.


The old LP was pushing about 8psi at idle and it ran the exact same way. The new pump didn't make a **** bit of a difference.

 

Based on what has been posted, you have no air in the fuel, and are fully pressurized at both the lift pump side and at the injector side. So, I would look to the following, IF your rebuilt VP is good - and that is a big if in today's market.

On the VP44 equipped trucks you have two sensors that are critical to starting. One is the MAP, which senses the manifold pressure and that enables the PCM/ECM to signal the processor on the pump to properly set the timing so it will start, and then shift so it will run. The other is the IAT that senses the intake air temperature so the PCM/ECM can tell the processor on the VP44 how rich to set for a cold start.

If either of those sensors go south, you will have a really tough time getting it to start.

Both sensors can be tested, and both should be cleaned even if they test good.

All VP44's are rebuilds, Bosch has not made any new pumps in years. Some rebuilders do not replace the internal processor if it passes minimal tests. and those tests are really minimal - bad processors will pass. Some do not use the linered rear housing and reuse the old housing that is worn, and others do not replace the front diaphragm that allows fuel to bypass the timing port on the pump.

If your pump processor is on the blink and you have a bad or dirty IAC or MAP, or are equipped with an automatic transmission and the APPS is starting to south you can spend a lifetime chasing trouble.

Unfortunately, unless you have a scanner that can read all the codes, including all those that you cannot get by flopping around like a chicken with no head by flipping the key, AND know how to do comparative analysis of which codes when found together mean what, you are best advised to take the rig to a Cummins Service Center or to you local Dodge Dealer if you can find one that is competent with the diesels.

If you are sure you have fuel to the VP, and fuel to the injectors, then do the APPS reset and see if that solves the trouble for a while. If so then replace the APPS, but be prepared to replace the VP44 at some not to distant time.

 

I have yet to pull a code out of this mess. The only code it has ever thrown is the MAP code, but that was only because I unplugged it at that time. No other codes have popped up.

I'm wondering how easy it's going to be to get the company to exchange the VP44? What if they get it back and claim it's in working order and ship the same one back to me? Bah, what if......I'm done with the **** truck anyways. For now, it's out of my life and I'm glad. Strangley, I'm still dead set on picking up a Cummins in the near future. Just gotta figure out what body style I want and how much I'm willing to pay to get it.

 

here's a possible .....
RacerRon has this one nailed. Pressurized combustion gases are leaking past the copper sealing washers on your injectors and passing to the tank through the fuel drain/return line.

This is causing your hard start because the air in the return line is causing a loss of prime.

With the nose of the truck high, the return fuel drains to the tank almost instantly and you'll lose prime quickly.

With the nose of the truck low (like backed into an uphill driveway), you'll keep the prime because the air in the return system can't migrate back to the engine because gravity is keeping fuel in place. Hence, the truck will start just fine as long as you park it nose down.

 

Sorry didn't read all the suggestions. There is a check valve before the vp44 isnt' there? Sounds like it is allowing the fuel to drain back?

 

that's been checked