To bleed the system, first make sure you have at least 5 gallons of fuel in the tank, do not trust the gauge.

Then locate the bleed bolt on the top of the fuel filter housing and loosen it.

Now locate the primer on the lift pump.

Pump the Primer on the lift pump until bubble free air comes out of the bleed bolt. This may take a while.

After doing so, crack open the OFV on the front passengers side of the Injector pump, and continue to pump the primer until bubble free air comes out.

Now give her a crank.  Do not crank for over 30 seconds. Let sit 2 minutes between cranking sessions to let cool down. It is also recommended to put a charger on the batteries as this may take a large amount of cranking.

If you feel you have all the air out, but it is not starting, crack open 3 injector lines at the injector and crank it over until fuel comes out, then tighten them up and you should be good to go!

If fuel refuses to come out of the injectors, now would be a good time to make sure the FSS is working as it should.

DO NOT use starting fluid! It’s like a drug, use it just once, and it will just keep wanting more! If necessary, unplug the grid heaters, remove the intake horn and use WD-40 while the engine is cranking. It is perfectly safe to keep the engine running using this method.

To avoid pumping the primer a couple hundred times. If you have an air compressor handy, you can take an air nozzle, wrap a rag around it and put it into the fuel tank fill-up. With the bleed bolt open, pressurize the tank to 10 psi MAX. This will push all the air out of the bleed bolt. Once done, crack open the OFV and use the lift pump primer. As pressurizing the tank will push fuel backwards through the return line and end up making a mess.

There are many ways to check for air in your fuel, in this article I’ll name off the more common ones.

Loosening Bleed Bolt method

Then locate the bleed bolt on the top of the fuel filter housing and loosen it a couple turns.

Now locate the primer on the lift pump.

Pump the Primer on the lift pump and check for air bubbles coming out of the bleed bolt. If bubbles continue to come out of the bleed bolt while you are priming, you likely have air in your fuel.

Return line into Jug method.

This is my preferred method, however it does require the engine to be running.

Normally the return from the Injector Pump gets fed back into the tank.  What we are going to do is redirect it into our own container, that way we can watch for air bubbles coming out.

To do this, we are going to splice into the return line with our own chunk of hose, you can see a good location to splice into in this picture

You are connecting to the rubber side of the hose, the hose size is 5/16”. The chunk of hose you connect to that one will need to be long enough to reach wherever you have the container.

Now start up the engine, and watch for bubbles coming out of the line, a couple large bubbles at first are normal, but if it continues to spit out small bubbles, you likely have air in your fuel.

To diagnose where your air leak is, go here: Finding & Fixing Your Air Leak.

In this article we’ll troubleshoot the mighty Cummins not wanting to breathe life.

I’m going to assume that the engine is cranking over like it should, but isn’t firing.  If you are having issues with the engine not cranking over, please wait patiently for me to write a “Starting System Diagnostics” article, Thank you.

Things to check:

FSS (Fuel Shutoff Solenoid).

Symtoms: Engine Cranks with no hint of wanting to start, or starts but shuts off once you let go of the key

The FSS is an electrical solenoid that lifts a lever on the injector pump.  The injector pump will not inject fuel into the engine if the FSS lever is not in the raised position.  For more information, Go to: Fuel Shutoff Selenoid (FSS)

No Fuel to injector Pump

Symtoms: Engine just cranks, possibility of white smoke out exhaust pipe.

Common issue if the engine ran out of fuel, has sat a while, or a part in the fuel system has been removed/replaced.  For troubleshooting and system bleeding procedures, Go to: Bleeding the Fuel System

Slipped Injection Timing

Symtoms: Engine just cranks, white smoke out exhaust pipe.

Likely issue if Injector pump was just re-timed.  To set the timing back to stock, go here: Confirming Stock Timing & Checking And Setting your Timing Back to Stock

So you found out that you have an air leak somewhere.  In this article we’ll find it.

In addition to this article, this is also a good read. Joe G's Fuel System Write-up

The air leak can be anywhere from inside the fuel tank, to the lift pump.

Finding the Air Leak

If the leak is large enough, it may drip when the engine is not running.  If you are not that lucky, you may have to persuade it to drip by taking an air compressor and pressurizing the fuel tank to 10 psi MAX.  to pressurize the tank, take an air nozzle, wrap a rag around it, and insert the contraption into the tank fill-up spout.  Now just watch for leaks!  If no leaks are found, the issue may be in the fuel tank.  Also, if the lift pump primer is leaking fuel, it will likely leak a little air as well.

Fuel Module

The fuel lines in the fuel module in the fuel tank can wear holes and suck air.

The Fix:

You will need to replace the lines in the tank, LarryB’s has a good kit.  Or you can install a Draw Straw or Sump.

Fuel Quick Connects at the tank.

They are called “quick connects”, but really they are the least quick connect fittings imaginable, especially at the odd angles you will be forced to be in in order to even see it.  The quick connect has an O-ring it in that can have a flat spot in them.

The Fix:

Replaced the quick-connect (3/8” Feed, 5/16” Return), or as many owners have done, replaced the rubber hose (3/8” Feed , 5/16” Return) that the quick connect is on, and just slide the hose over the male portion of the quick connect on the fuel module.  This method has been used many times, and I have yet to hear of any failures.

Fuel Lines along the Frame

If your truck is somewhat of a rust bucket, the fuel lines are going to be one of the first things to go.

The Fix:

You will need to replace the lines, there is a large array of replacment options, including stainless steel lines, and the more popular and DIY friendly, Rubber hose option.   If you use rubber hose, make sure it is Diesel Rated.  Marine Grade would be recommended.  Trident A-15 Marine Fuel Line is good stuff, at an affordable price.  LarryB’s also has good kit.  When re-doing the fuel system, if you bypass the pre-screen (I wouldn’t), make sure to use some form of screen before the lift pump.  Avoid too much restriction as the lift pump doesn’t like having to pull through to fine of a filter.

Fitting sizes are as follows:  Lift pump inlet – ½” BSPT (NPT work fine), Pre-filter inlet/outlet – 3/8” NPT.

Fuel Heater/Pre-screen unit

The fuel heater is well known for its likability.  The rest of the prescreen unit is very reliable.

The Fix:

Delete the pre-heater. 

Pre-Filter to Lift Pump Hose.

It is common for this hose to leak air, it may look good on the outside, but the connections can leak air.

The Fix:

The cheapest place to get a new ones, surprisingly, is the Dodge dealer, Cummins Dealer is much more expensive.  Or you can get one from here http://www.genosgarage.com/product/mop-04746638/hoses

Lift Pump

The Inlet Fitting may leak, along with the primer seal.

 The Fix:

If the issue is the primer seal, some of the old pumps has a normal O-ring that sealed it off.  If your is like that you can try replacing the O-ring.  Otherwise if your pump in not like that, then you need to replace the Lift Pump.  http://www.genosgarage.com/product/pump-4988747-kit/fuel-pumps

Big thanks to: Illflem, and Rumbus528 on youtube.

Adjusting the idle speed on the diesel engine is not difficult. The adjustment is located on the driver side of the injector pump near the rear of the pump. You will need a 10 mm wrench.

Correct speed is:

• 1994-1998 with AT - in drive with AC on 750 -800 RPM
• 1994-1998 with manual in neutral with AC on 750-800 RPM
• NOTE: These speeds may cause stalling when the engine is cold. If this is a problem for you, bump the idle speed to 900 RPM.

See TSB 18-07-98, which warns that the dash tachometer is not accurate enough for proper adjustment. If you have adjusted the idle using the tachometer and have any of the problems listed in the TSB, you may use your tachometer to get the idle speed in the ballpark and then use your judgment to fine tune the idle adjustment.

Idle Speed Adjustment

There are several ways to reach the idle adjustment.

Go in from the front of the truck - Lay over on the radiator and snake the right arm back and down to the adjustment.

From a short stepladder beside the driver side tire - Reach down from behind the injector pump to the adjustment.

Stand on 5-gallon bucket by the drivers wheel, lean in under the hood and put the back of your head against the hood insulation - reach your right hand under the brake master AND under the ABS lines to the back of the pump.

From any of the positions above, you can easily feel a vertical bolt with the extra threads on the bottom. The locknut is on the bolt threads below the boss on the pump housing.

An open end wrench will usually loosen the locknut, it is difficult to get a box end wrench to fit onto the locknut.

Loosen the 10 mm Locknut on the low idle adjusting screw at the rear of the injector pump.

Take the left hand and gently push the linkage rearward to take the pressure off and with the right hand.  Look at the RPM and repeat to get the results you're after.

turn the idle screw counter clockwise (up) to increase idle speed

turn the idle screw clockwise (down) to decrease idle speed

Tighten the 10 mm locknut when the idle speed is correct.

Another version from Jeff Hammaker:

Question> How do I adjust the idle speed on my Ram diesel? The idle speed seems too high.

First, trace the accelerator linkage to the connection on the fuel pump. With the ENGINE OFF have someone floor the accelerator and watch the fuel arm move. The best position I can describe is that it is under and to the left of the fuel filter on the rear of the fuel pump. A Flashlight and a mechanics telescoping inspection mirror would best serve as your visual aids as there is little room to move around and get a view of this area.

Once you have located the fuel arm the idle adjustment bolt is where the fuel arm normally rests on. It is easier to see and adjust if you have someone hold the accelerator down. The 10mm bolt that the fuel arm rests on threads into the bracket that you see and has a 10mm lock nut on the underside of the bolt. Loosen the lock nut and adjust the bolt on top in for a lower idle speed and out to raise the idle. I have found that the truck works well with the idle set at 750 rpms and this is the first white line below the 1000 rpm mark on the tach. Start the engine and observe the idle speed and put the truck in gear (if automatic) and turn the AC on. If the truck doesn't try to stall then you are set. Make sure that you tighten the locknut good when you get your desired idle speed.

An observation I have made. With the idle speed set below the factory set point it is easier to start the truck when you gently put some slight pressure on the accelerator while cranking the engine. Applying to much pedal will generate a a real smoke cloud so its an experimental thing that you need adjust by feel until you get it just right. Any confusion let me know.

Video;

If you have any further questions, please feel welcome to ask them on the Mopar1973Man Forum!

Cleanliness is very important, any dirt or debris that get inside the injector will wear on the tight tolerance parts.

Injector Diagram:

Torque Specs

• 15mm Nozzle Retaining Nut - 22 ftlb's
• 10mm Injector Bleed-off bolt - 6 ftlb's
• 24mm Injector Retaining Nut - 44 ftlb's

Things we'll need.

• 19MM Open end wrench (For Pop Tester).
• 15MM Open end/box end wrench (For Injector Disassembly and Pop Tester).
• Torque Wrench with 15mm Deep Socket.
• Vice, Preferably Smooth Jaw.
• Lubrication Oil (I use 50% Diesel, 50% engine oil).
• Pen Magnet for Shim Removal.
• Small pick (I like a 5/64 hex key, it fits tight into the shim for easy removal).
• Adjustment Shims (For Adjusting Pop Pressure).
• Caliper (For measuring Shim packs for easier pressure adjustment).
• Pop Tester (For checking Pop Pressure)
• Fluid for Pop Tester (I use 95% Diesel, 5% 2-Stroke Oil)

Clean the injectors thoroughly before disassembly. 

I Highly recommend you only work on one injector at a time to prevent mixing parts between them.  

Clamp Injector in the Vice.  Do not Clamp onto the Injector Return Outlet Port.  Use 15MM Wrench to loosen Nozzle Clamping Nut until Hand Tight.

Remove the injector from the vise, put the injector close to your work bench before finish removal of the Nozzle Retaining Nut.  This will prevent small parts from falling and disappearing.

Disassemble the injector further, note the orientation of everything, it should come apart like this.

Clean All Parts Thoroughly.  Use Brake Cleaner/Carb Cleaner and Compressed Air to blow backwards through the Feed Passage in the Injector Body to clean the Edge Filter.

Carefully remove the Needle from the Nozzle, if necessary use some pliers and carefully pull the needle out, make sure not to scratch the nozzle mating surface.  If the needle still won't come out (very unlikely for a used nozzle in good shape) then reassemble the injector and install it into the injector Pop tester and use it to pop the needle loose.  And then once again disassemble the injector and continue cleaning.

 Use Brake Cleaner/Carb Cleaner and Compressed air to clean out the nozzle, blowing into the needle hole, and the feed passage.

Inspect the injector needle for wear or pitting at the tip.

Here is a video showing a good and bad needle.  If the injector needle is damaged, both it and the nozzle must be replaced.  If this is the case, it is highly recommended that you replace the whole set.

Once clean, use your lubricating oil and put a couple drops on the injector needle before inserting it into the nozzle.  Make sure to lube both the needle tip, and the largest diameter portion of the needle.  Well used nozzles aren't picky about the type of oil, you could even get away with straight engine oil.  However new nozzle have much tighter clearances so are very picky about oil thickness, Use a maximum of 50% oil and 50% diesel.  To thick will warrant inaccurate readings with the Pop Tester.  If the injector isn't working correctly on the Pop Tester,  Disassemble the injector, clean the nozzle thoroughly, and make sure you're using a thin enough lubricating oil.

Once done, insert the Needle back into the Nozzle.

Back to the injector body.

Install all the shims back into the hole, if you are installing extra shims to raise the Pop Pressure, install them under the main thick shim.  As a general rule, .01mm of shim will raise the pop pressure 1.5-2 Bar.  Once the shims are in place, insert the spring, if the spring does not sit approximately flush with the injector body, the shims are not seated correctly.  Carefully use the spring as a ram-rod to seat the springs.

Here is the shims and spring inserted correctly.

Then install the spring seat, note the orientation.

Now install the Valve Stop Plate.  Once again, note the orientation, the conical side should face the injector body.

When installing, make sure to line up the Feed passages.

Once installed Dribble a little Lubricating Oil onto the Valve Stop Plate, This will lube many key things, most importantly the injector body threads.  Also dribble some oil into the Injector Nozzle Nut, this will again lube the threads, as well as where it seats against the nozzle.

Once done, install the nozzle, again make sure to line up the Feed Passage.

Install the nozzle, then the nut.  Tighten the nut until you start to feel spring tension, then back it off a turn or two.  Grab the nozzle tip with your fingers and pull up and down on it, there should be play, if not, loosen the Nozzle retaining nut further until there is some play.  Then try and spin the nozzle tip, while pulling in and out.  The nozzle should not spin.  If it does then you do not have the aligning dowels in incorrectly.  Disassemble and re-check your work.  if the nozzle does not spin, everything is good to go and you can tighten the Nozzle retaining nut down to 22 ftlb's.

If you are changing the pop pressure, or installing new nozzles, it is highly recommended that you Pop test the injectors once down.  This will let you know if you should shim the injectors, or if some nozzles aren't spraying correctly.

I highly recommend you do your pop testing outdoors, or in a very well ventilated area (Due to the fact that it was raining, I had to take these pictures indoors).

Good spray pattern:

5x.010 VCO @ 280 Bar

7x.0105 SAC @ 320 Bar

7x.0105 SAC @ 260 Bar

5x.013 SAC @ 260 Bar

7x.0105 SAC With Bad Spray pattern, it may look like it's just injecting less fuel, but it's actually the same amount.

1. Clean area thoroughly.
2. Remove 10mm bolts holding down intake horn, oil tube, injector lines, grid heater, and injector return line.
3. Remove injector lines (19mm).
4. Remove injector return line 10mm banjo bolts.
5. Remove injector return line 12mm banjo bolt at fuel filter.
6. Remove injector return line.
7. Loosen Injector hold down nuts.
8. Remove injectors.

In this article we’ll troubleshoot low power, or the engine just not running right.

If the engine doesn’t want to start at all, go here: Engine Not Starting

Is it normal?

If you start the engine, and immediately floor it, it will get to about 2000 RPM, and then pop, sputter, white smoke, and RPM won't climb.  This is somewhat normal.  Same goes for when asking for much power when the engine is cold.  There are a couple things that compound the issue:  

• Cold Weather.
• Dysfunctional Grid Heaters.
• Disconnected Intake Plumbing.
• Turbo Removed.
• Low Fuel Pressure or Air in the fuel.

Basically, If you are starting the engine on a test stand, it is perfectly normal.

Things to check:

FSS (Fuel Shutoff Solenoid).

Symtoms: Engine Low on power, No Sputtering/misfire/smoke.  Engine runs normally, just runs out of power quick.

The FSS is an electrical solenoid that lifts a lever on the injector pump.  If FSS isn’t adjusted correctly, or is full of grime, it will limit the amount of fuel the injector pump injects and thus limit power.  For more information, Go To: Fuel Shutoff Solenoid (FSS)

Low Fuel Pressure/Unhealthy fuel system.

Symtoms: Possible Hard Starting, Possible Misfire at idle, Possible White Smoke, Especially when engine is powering out.

If the engine takes a couple cranks to start after sitting overnight, check for air in the fuel.  Go Here: Checking For Air In Your Fuel

It is highly recommended that you install a fuel pressure gauge to avoid blindly throwing parts at the problem.  Go Here: How to install Fuel Pressure Gauge

Fuel Pressure should stay above 20 psi at all times, if it goes down to 15 psi, you know you have a problem, to diagnose the cause. Go Here: JoeG's Fuel System Write-Up

Slipped Injection Timing

Symtoms: White smoke, Engine Knocking, Low Power.

Very likely issue if Injector pump was just retimed or replaced.  For troubleshooting procedures, Go Here: Confirming Stock Timing & Checking and Reseting Timing Back To Stock

Warped Injector Pump Plungers.

Symtoms: Runs normal when cold, Misses and Dies once warm.

To test, once the engine starts to misbehave, pour a bucket of water over the injector pump to cool it down.  If the engine starts running fine again, look into getting a new injector pump.

If you're using a dial indicator, you'll need the plunger lift charts, I've supplied them at the bottum of the article!  One's metric and the other is inches, otherwise they're identical.

OK, well first things first is you'll need to find #1 TDC.  TDC (Top Dead Center) is where #1 piston is at the absolute top of it's stroke.  We also need to make sure that's it's the compression stroke, both are very important for a successful timing job.  Always double check your TDC and make sure it's the compression stroke, remember, if it's not, you need to spin the engine 360°.

• Place engine at approximate TDC Compression.
• Remove DV and Install Dial Indicator into Plunger.
• Rotate the engine BACKWARDS (CCW when standing in front) until the dial indicator stops dropping.
• Check the Dial indicator to make sure it's still contacting the plunger and hasn't maxed out, if it's still riding on the plunger continue.
• Zero the Dial Indicator
• Rotate the engine FORWARD until your set lift is achieved, lets say it's a 215 pump and we're shooting for 17°, so that's 5.73mm.
• Pop the injection pump gear off, careful to do it evenly as to not rotate the pump.
• Once the gear is off, rotate the engine to exact #1 TDC Compression.
• Clean the shaft thoroughly with brake cleaner or electrical contact cleaner (do not use carb cleaner).
• Torque Injection Pump gear to 20 ft/lb's and let sit to seat the gear on the shaft.
• Tighten down the Injection Pump gear nut to 144ft/lbs as specified in the FSM.
• Recheck your TDC and plunger lift to ensure nothing slipped while tightening the gear.