I've spent all day trying to figure why the truck keeps running out of fuel and why it puts air unto the fuel tank (guessing primer assembly leaks internally) It's the mitsubishi 4 cylinder diesel and I can't find any info on this box truck. First how does fuel get to the injection pump? I can't find a fuel pump anywhere. No leaks, popped valve cover, nothing. Engine runs fine as long as you keep priming it. After it warms up it blows nasty blue smoke when you try to accelerate. I'd like to start with why it's running out of fuel. Doesn't seem to leak and holds pressure on both sides of the primer/filter assembly. Thanks in advance
HELP WITH 2003 MITSUBISHI FUSO DIESEL 4M50
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plh
Explorer
My 4D56 uses the injection pump to suck fuel from the tank. No other fuel pump. Make sure there are no leaks (even tiny) in you fuel lines and that the fuel filter, water separator etc is clean and free flowing. What's the history of this engine? Did it run correctly a short time ago?
Last edited:
lordtrunks
camp loser
Have you changed the fuel filter? clogged filter will get you exactly what your saying.
Sorry my first post. I found the other thread. I was guessing the injection pump had to pull fuel. New fuel filter and no external leaks. I saw a low volume pump for sale for this truck. I'm guessing it goes into the injection pump but I can't find a manual or diagram for the engine or injection pump.
lordtrunks
camp loser
maybe gas in your take a friend had an employee put "super diesel" in the tank and which killed the fuel pump soon after the blue smoke you speak of could be a sigh of gas mixed in your diesel
this is for chevy's but same idea for just about any diesel
Subject:
Diesel Engine Hesitation, White Smoke, Rough Idle, Lack of Power, Hard or No Start, Stall
(Check for Diesel Fuel Contamination or Poor Fuel Quality)
Models:
1994-98 Chevrolet and GMC C/K, G, P Models
with 6.5L Diesel Engine (VINs P, 5, Y, F - RPOs L49, L56, L57, L65)
Condition
Some owners of the above listed vehicles may comment that their vehicle has a rough idle, lacks power, is difficult or won't start, and may occasionally stall. In addition, the MIL (Malfunction Indicator Lamp) or WIF (Water in Fuel lamp) may be illuminated and there may be fuel injection pump DTC's in history.
Do not replace the fuel injection pump for this condition without first eliminating both fuel contamination and fuel quality as sources of the customer's concern.
Cause
The diesel engine fuel system may be contaminated or fuel quality may be poor. If water, gasoline, or other contaminants are in the diesel engine fuel supply, or if fuel quality is poor, driveability complaints or injection pump DTC's may be set. The contaminants must be removed and the fuel system flushed prior to any repairs or diagnostics being performed. In addition, a known good supply of fuel must be used in the vehicle to obtain proper engine performance.
Correction
If a driveability condition exists, and/or if diesel injection pump DTC's are present when performing an On Board Diagnostics (OBD) system check, check for fuel system contamination and verify fuel quality prior to any other repairs. Do not replace the fuel injection pump without first eliminating both fuel contamination and fuel quality as sources of the customer's concern.
Several different types of contamination can occur in diesel fuel. Fungi (mold), water, or gasoline can sometimes be found in a diesel engine fuel supply. In addition, the customer may use an incorrect fuel grade which can cause driveability or mileage concerns.
Testing for Fuel Contamination
If fungi, water, or gasoline contamination are suspected, the technician should first inspect the fuel filter and/or fuel filter housing as described in the Engine Controls section of the appropriate Service Manual. For example this procedure is listed in the 1998 C/K Service Manual Book 4, Engine Controls Section, Page 6-2569.
Water or Fungi (Mold) in the Fuel System
If water or fungi (mold) are detected when inspecting the fuel filter or filter housing, go to the Cleaning Water from the Fuel System procedure listed in the Engine Controls Section of the appropriate Service Manual. Using the 1998 C/K again as an example, go to 1998 book 4, Engine Controls, Cleaning Water from the Fuel System on Page 6-2569. This section has the procedure for purging water from the fuel system and describes when to use a bacteria biocide.
Gasoline in the Fuel System
Gasoline is also sometimes inadvertently mixed in with diesel fuel. This also can lead to numerous driveability conditions, unusually high fuel rates observed on the Tech 2, fuel injection pump and nozzle damage, and if not eliminated from the fuel system, multiple trips into the dealership for customers.
If gasoline contamination is detected when checking the fuel filter or filter housing, go to the Cleaning Gasoline from the Fuel System procedure listed in the Engine Controls section of the appropriate vehicle line service manual. Using the 1998 C/K as an example, this procedure is found in Book 4, Engine Controls section, Page 6-2570.
What Type of Diesel Fuel Should a Customer Use?
Poor fuel quality may also cause driveability complaints such as hesitation, stall, lack of power. slow or no start. For best results, Number 2-D diesel fuel should be used year round (above and below freezing temperatures) as oil companies blend Number 2-D fuel to address different climates. Number 1-D diesel fuel may be used in very cold temperatures, when it stays below O°F (-18°C). A power and fuel economy loss will occur when using Number 1-0 fuel. In addition, if Number 1-D fuel, or a 2-D winter blend, is used in a warm or hot climate (such as when a vehicle is shipped from a cold weather area to a warm weather area with the tank already filled with cold weather fuel), stalling, rough idle, poor or no start and other driveability symptoms may occur when the engine is hot. In addition, an unusually high fuel rate may be observed on the Tech 2 scan tool compared to a similar vehicle using Number 2-D fuel.
Specific Gravity Testing
If driveability conditions exist such as rough idle, stalling, hard or no start, check for water or gasoline in the fuel first. If OK, check fuel specific gravity using the fuel quality hydrometer. This procedure provides a general indication of fuel quality. The Specific Gravity Testing procedure is listed in the Engine Controls Section of the Service Manual. For example, 1998 C/K use Book 4, Engine Controls section Page 6-2570. Number 2-D fuel should be between 30-39 API gravity, and Number 1-D should be between 39-44 API gravity. Refer to the Service Manual chart in the Specific Gravity Testing Section for more details.
Summary
Do not replace a fuel injection pump without performing all normal Service Manual diagnostics including DTC's, symptoms, and a review of the customers comments. Always check for fuel quality and possible contamination. This is critical to properly diagnosing a diesel engine driveability complaint.
this is for chevy's but same idea for just about any diesel
Subject:
Diesel Engine Hesitation, White Smoke, Rough Idle, Lack of Power, Hard or No Start, Stall
(Check for Diesel Fuel Contamination or Poor Fuel Quality)
Models:
1994-98 Chevrolet and GMC C/K, G, P Models
with 6.5L Diesel Engine (VINs P, 5, Y, F - RPOs L49, L56, L57, L65)
Condition
Some owners of the above listed vehicles may comment that their vehicle has a rough idle, lacks power, is difficult or won't start, and may occasionally stall. In addition, the MIL (Malfunction Indicator Lamp) or WIF (Water in Fuel lamp) may be illuminated and there may be fuel injection pump DTC's in history.
Do not replace the fuel injection pump for this condition without first eliminating both fuel contamination and fuel quality as sources of the customer's concern.
Cause
The diesel engine fuel system may be contaminated or fuel quality may be poor. If water, gasoline, or other contaminants are in the diesel engine fuel supply, or if fuel quality is poor, driveability complaints or injection pump DTC's may be set. The contaminants must be removed and the fuel system flushed prior to any repairs or diagnostics being performed. In addition, a known good supply of fuel must be used in the vehicle to obtain proper engine performance.
Correction
If a driveability condition exists, and/or if diesel injection pump DTC's are present when performing an On Board Diagnostics (OBD) system check, check for fuel system contamination and verify fuel quality prior to any other repairs. Do not replace the fuel injection pump without first eliminating both fuel contamination and fuel quality as sources of the customer's concern.
Several different types of contamination can occur in diesel fuel. Fungi (mold), water, or gasoline can sometimes be found in a diesel engine fuel supply. In addition, the customer may use an incorrect fuel grade which can cause driveability or mileage concerns.
Testing for Fuel Contamination
If fungi, water, or gasoline contamination are suspected, the technician should first inspect the fuel filter and/or fuel filter housing as described in the Engine Controls section of the appropriate Service Manual. For example this procedure is listed in the 1998 C/K Service Manual Book 4, Engine Controls Section, Page 6-2569.
Water or Fungi (Mold) in the Fuel System
If water or fungi (mold) are detected when inspecting the fuel filter or filter housing, go to the Cleaning Water from the Fuel System procedure listed in the Engine Controls Section of the appropriate Service Manual. Using the 1998 C/K again as an example, go to 1998 book 4, Engine Controls, Cleaning Water from the Fuel System on Page 6-2569. This section has the procedure for purging water from the fuel system and describes when to use a bacteria biocide.
Gasoline in the Fuel System
Gasoline is also sometimes inadvertently mixed in with diesel fuel. This also can lead to numerous driveability conditions, unusually high fuel rates observed on the Tech 2, fuel injection pump and nozzle damage, and if not eliminated from the fuel system, multiple trips into the dealership for customers.
If gasoline contamination is detected when checking the fuel filter or filter housing, go to the Cleaning Gasoline from the Fuel System procedure listed in the Engine Controls section of the appropriate vehicle line service manual. Using the 1998 C/K as an example, this procedure is found in Book 4, Engine Controls section, Page 6-2570.
What Type of Diesel Fuel Should a Customer Use?
Poor fuel quality may also cause driveability complaints such as hesitation, stall, lack of power. slow or no start. For best results, Number 2-D diesel fuel should be used year round (above and below freezing temperatures) as oil companies blend Number 2-D fuel to address different climates. Number 1-D diesel fuel may be used in very cold temperatures, when it stays below O°F (-18°C). A power and fuel economy loss will occur when using Number 1-0 fuel. In addition, if Number 1-D fuel, or a 2-D winter blend, is used in a warm or hot climate (such as when a vehicle is shipped from a cold weather area to a warm weather area with the tank already filled with cold weather fuel), stalling, rough idle, poor or no start and other driveability symptoms may occur when the engine is hot. In addition, an unusually high fuel rate may be observed on the Tech 2 scan tool compared to a similar vehicle using Number 2-D fuel.
Specific Gravity Testing
If driveability conditions exist such as rough idle, stalling, hard or no start, check for water or gasoline in the fuel first. If OK, check fuel specific gravity using the fuel quality hydrometer. This procedure provides a general indication of fuel quality. The Specific Gravity Testing procedure is listed in the Engine Controls Section of the Service Manual. For example, 1998 C/K use Book 4, Engine Controls section Page 6-2570. Number 2-D fuel should be between 30-39 API gravity, and Number 1-D should be between 39-44 API gravity. Refer to the Service Manual chart in the Specific Gravity Testing Section for more details.
Summary
Do not replace a fuel injection pump without performing all normal Service Manual diagnostics including DTC's, symptoms, and a review of the customers comments. Always check for fuel quality and possible contamination. This is critical to properly diagnosing a diesel engine driveability complaint.