Fuel system diagnosis, usually the hardest part of any B-series job, gets two full chapters in this 936-page Cummins B3.9, B5.9 troubleshooting and repair manual PDF (OEM 3666087-01), and from there the book widens to the block, head, valve train, lubrication, cooling, turbocharger and compressed air systems. Symptom charts take up a large share of the front section, tracing each complaint to its probable cause, and wiring diagrams lay out the electrical circuits. The cylinder block chapter is the longest in the book, covering main and rod bearings, connecting rods and the camshaft, while a separate specifications section holds the limits you measure against. Confirm the transfer pump makes at least 175 kPa [25 psi] at rated rpm, then torque the high-pressure fuel lines to 30 N·m [22 ft-lb]. A rebuild stalls on the one clearance you can't find. Chapter bookmarks and a searchable text layer take you straight to that spec before anything goes back together.
What's Inside This Cummins B3.9, B5.9 Manual
| System | Pages | Key Topics |
|---|---|---|
| Introduction | 7-16 | About the Manual, General Safety Instructions, General Repair Instructions |
| Engine Identification | 17-48 | Engine Dataplate, Cummins Engine Nomenclature, Fuel Injection Pump Dataplate |
| Troubleshooting Symptoms | 49-128 | Troubleshooting Procedures and Techniques, Troubleshooting Symptoms Charts |
| Complete Engine | 129-140 | Engine Removal, Engine Installation, Engine Painting |
| Cylinder Block | 141-260 | Bearings, Connecting Rod, Main, Camshaft |
| Cylinder Head | 261-292 | Cylinder Head General Information, Cylinder Head Disassembly, Valve |
| Rocker Levers | 293-308 | Overhead Set, Rocker Lever, Rocker Lever Cover |
| Cam Followers/Tappets | 309-324 | Cam Followers/Tappets General Information, Push Rods or Tubes, Tappet |
| Fuel Systems | 325-434 | Fuel System General Information, Fuel Consumption, Fuel Flow |
| Injectors and Fuel Lines | 435-476 | Fuel Manifold, Fuel Supply Lines, Injector |
| Lubricating System | 477-520 | Lubricating Oil System General Information, Lubricating Oil Pan, Lubricating Oil Pump |
| Cooling System | 521-582 | Cooling System General Information, Coolant Thermostat, Water Pump |
| Drive Units | 583-588 | Hydraulic Pump Drive, Hydraulic Pump Drive Gear and Shaft |
| Air Intake System | 589-656 | Air Intake System General Information, Aftercooler, Turbocharger |
| Exhaust System | 657-668 | Exhaust Manifold, Exhaust Restriction |
| Compressed Air System | 669-722 | Compressed Air System General Information, Air Compressor Cylinder Head, Air Compressor Unloader and Valve Assembly |
| Electrical Equipment | 723-762 | Electrical Equipment General Information, Alternator, Batteries |
| Engine Testing | 763-792 | Engine Testing General Information, Engine Testing Chassis Dynamometer, Engine Run-In Engine Dynamometer |
| Mounting Adaptations | 793-818 | Engine Support Bracket, Flywheel, Flywheel Housing |
| Miscellaneous | 819-826 | Cup Plug, Pipe Plug, Expansion Plug |
| Specifications | 827-908 | Cylinder Block Specifications, Cylinder Head Specifications, Cooling System Specifications |
| Component Manufacturers | 909-914 | Component Manufacturers Addresses |
| Service Literature | 915-918 | Additional Service Literature, Service Literature Ordering Location |
Quick Reference Specifications
| Specification | Value | Page |
|---|---|---|
| All Models | ||
| Maximum Inlet Restriction to the Fuel Transfer Pump Must Not Exceed | 100 mm Hg [4 in Hg] | p. 332 |
| Maximum Allowable Return Line Restriction | 518 mm Hg [20.4 in Hg] | p. 332 |
| High-Pressure Fuel Lines Torque | 30 N·m [22 ft-lb] | p. 353 |
| Low-Pressure Fuel Supply Fitting Torque | 15 N·m [133 in-lb] | p. 353 |
| Bosch VE solenoid torque | 43 N·m [32 ft-lb] | p. 400 |
| Stanadyne DB4 solenoid valve torque | 14 N·m [124 in-lb] | p. 400 |
| Fuel transfer pump mounting capscrews torque | 24 N·m [18 ft-lb] | p. 411 |
| Fuel line to fuel transfer pump connection torque | 24 N·m [18 ft-lb] | p. 411 |
| Nozzle retaining nut torque | 30 N·m [22 ft-lb] | p. 466 |
| Injector hold-down nut torque | 60 N·m [44 ft-lb] | p. 467 |
| B3.9 | ||
| B3.9 Engine Weight (dry) | 308 to 329 kg | p. 22 |
| B5.9 | ||
| B5.9 Engine Weight (dry) | 388 to 411 kg | p. 22 |
Cummins B3.9, B5.9 Common Problems This Manual Covers
Cummins B3.9 and B5.9 fuel transfer pump low output pressure with engine power output low
Measure transfer pump output pressure at rated rpm and compare it with the 175 kPa [25 psi] minimum on page 332. Then check fuel pressure gallery pressure against 140 kPa [20 psi]. If output is low, replace the pump. Torque the mounting capscrews and the fuel line connection to 24 N·m [18 ft-lb] per page 411.
Manual Section: Fuel Systems p. 332Clogged fuel filter or restricted supply line, engine acceleration or response poor
Measure the pressure drop across the fuel filter. The limit on page 332 is 35 kPa [5 psi], so replace the filter if it reads higher. Check inlet restriction at the transfer pump against 100 mm Hg [4 in Hg] and return line restriction against 518 mm Hg [20.4 in Hg]. Bleed the air out and torque the bleed screw to 9 N·m [80 in-lb] per page 412.
Manual Section: Fuel Systems p. 332Fuel shutoff solenoid fault, engine will not start or will not shut off
Test the Synchro-start solenoid windings with an ohmmeter following page 397. On a 12 VDC, 44.45-mm canister, pull-in must read 0.198 to 0.242 Ohms and hold-in must read 10.00 to 12.21 Ohms. Confirm the canister size and voltage first, because the 50.8-mm and 24 VDC values are different. Replace the solenoid if either winding reads out of range.
Manual Section: Fuel Systems p. 397Suspect injector or high-pressure fuel line connection, engine runs rough or misfires
Remove the suspect injector and service it on the bench. Torque the nozzle retaining nut to 30 N·m [22 ft-lb] per page 466. Reinstall it and torque the hold-down nut to 60 N·m [44 ft-lb] per page 467. Tighten the high-pressure fuel line fitting to 38 N·m [28 ft-lb] per page 468 before you restart the engine.
Manual Section: Injectors and Fuel Lines p. 467Worn main bearings suspected, engine noise excessive with a main bearing knock
Remove the main bearing caps and inspect the bearing shells and crankshaft journals before reassembly. When the caps go back on, torque the main bearing capscrews in stages following page 163. Step 1 is 60 N·m [44 ft-lb] and Step 2 is 90 N·m [66 ft-lb]. Complete any further steps listed there before you rotate the crankshaft.
Manual Section: Cylinder Block p. 163Frequently Asked Questions
What are the torque specifications for the cylinder head bolts on a B3.9 or B5.9 engine?
The cylinder head bolts must be tightened in a specific three-step sequence. For step 1, tighten all 26 capscrews to 90 N•m [66 ft-lb]. For step 2, tighten the six long capscrews (No. 4, 5, 12, 13, 20, and 21) to 120 N•m [89 ft-lb]. For step 3, retighten the short capscrews to 90 N•m [66 ft-lb], repeat step 2, and finally turn all capscrews 90 degrees. p. 276
What is the injector torque specification for a Cummins B5.9 engine?
The injector hold-down nut should be tightened to 60 N•m [44 ft-lb]. Ensure the injector's protrusion is aligned with the notch in the bore and that the O-ring is properly seated in the groove. p. 467
What are the replacement specifications for the fuel lift pump on a Cummins B3.9, B5.9 engine?
The fuel lift pump mounting capscrews should be tightened to 24 N•m [18 ft-lb]. When installing the fuel line to the fuel transfer pump and fuel filter head, use two wrenches to tighten the connection to 24 N•m [18 ft-lb]. p. 411
What is the correct valve clearance for the intake and exhaust valves on a B3.9 or B5.9 engine?
The intake valve clearance is 0.25 mm [0.010 in] and the exhaust valve clearance is 0.51 mm [0.020 in]. These measurements should be taken with the engine cold. p. 22
What is the torque spec for the main bearing capscrews on a Cummins B3.9, B5.9 engine?
The main bearing capscrews must be tightened in a three-step sequence. Step 1 is 60 N•m [44 ft-lb], step 2 is 90 N•m [66 ft-lb], and step 3 is to turn the capscrews clockwise 90 degrees. p. 163
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