Chevy Duramax

At Dallas Diesel, we are the premier source for all light and medium duty diesel engines. As such we often get calls from owners of one of the most popular diesel truck brands, the Chevy Duramax, complaining of engine troubles. More often than not these troubles are associated with a faulty high pressure pump system. If you have been experiencing problems with your Chevy Duramax engine of any model year, don’t worry, we are just a phone call away and we are here to help.


What is the Function of the High Pressure Pump?
The high pressure pump serves as a regulator, controlling your fuel rail pressure. The rail pressure is the pressure used in starting your engine and, to start your engine, should be at about 2500 PSI. High pressure fuel flows from the high pressure pump to your injectors. Hollow check balls in the injectors rise when fuel solenoid is actuated, allowing an injection to take place. In turn, these injections work to start your engine.
Symptoms of a Faulty High Pressure Pump
If you have experienced any of the following symptoms while starting or driving your truck, you may have a faulty high pressure pump. Below we will explain what the most common symptoms are, how they are caused, what you can do to diagnose your problem, and when it is time to bring your vehicle to us, at Dallas Diesel.
• No Start or Hard Start
– Check your fuel filter; if it is restricting air flow, this could be the cause of your problem. You can replace this and determine if the problem still exists after replacement.
– Bring it into us and we can use a vacuum pressure gauge to check the suction you have under load. If you have too little suction, your truck could be sucking in air. We would then check for air in your fuel system and, if found, will clear your lines.
– We can also determine what your actual rail pressure is and weigh this against the 2500 PSI needed to start your engine.
• Black Smoke
– You should first check your air filter. Often, a dirty air filter can result in black smoke.
– If you notice black smoke and, also, hear a high pitched squeal while driving at fuel load, this could mean that you have a boost leak. At Dallas Diesel, we can easily take care of this for you.
– If the condition persists, make an appointment with us and we will cut out each of your cylinders, one at a time, using a scan tool to determine if the issue is resulting from a bad cylinder.
• Misses
– We will check to see if a problem lies in one of your cylinders or if you have a missing or damaged chamber gasket. We can also determine if the engine is missing due to low compression.
• Knock
– If your engine is knocking, it is best to bring it into us right away. We will look to see if this is occurring because of trouble with one of your cylinders or an injector.
• Surge at Idle
– A surge at idle can often be caused by air in the fuel system. If you bring your vehicle into us, we may rule this out and check to see that your rail pressure is consistent. Inconsistent rail pressure can be a sign of a bad fuel pressure regulator.
• White/Blue Smoke at Idle When Cold
– The appearance of white or blue smoke at idle can be considered normal at low temperatures and in specific altitudes. Under these circumstances, the smoke should dissipate within one minute.
– Further, if your vehicle is left to idle for an excessive amount of time, this condition could be considered normal.
– If you are seeing white or blue smoke and neither of the above two conditions are occurring, then we can inspect to determine if you have a bad injector or if your rail pressure is off.
• Low Power
– You should check to see if you have a dirty fuel filter; the decrease in circulation caused by this can result in low power.
– If your filter is in good condition, we can examine the fuel supply pump pressure and wastegate control solenoid in the shop.
• No Start, Dies Intermittently or Stalling
– This is a condition often caused by a bad Pump Mounted Driver or Fuel Control Solenoid Driver. You will have to bring your vehicle into our mechanics so we can perform the following tests to determine where your issue is originating:
We will first check for a bad noise suppression harness
Then, we will check for air in your fuel system which could mean a fuel filter condition or supply pump damage
We will also ensure that all the vehicle’s harness grounds are secured
If, after complete testing, we determine the problem lies in your Pump Mounted Driver, we will then replace it; likewise with your Fuel Solenoid Driver


Good Information to Know
Although the high pressure pump has been the source of many common problems in the Chevy Duramax, it can often be misdiagnosed. When you bring your vehicle into our diesel-trained technicians at Dallas Diesel they will investigate all possible sources of your issue to ensure that we resolve the problem the first time, quickly and efficiently. Here are some other things our technicians will test for when you bring us your Chevy Duramax that has been emitting the above symptoms:
• Dilution
– Dilution problems usually occur because of a cracked injector. We can use a vacuum test to see if this is the cause of dilution. We will also look to see if the dilution might be caused from a leak at your high pressure pump driveshaft seal.
• Fuel Supply and Fuel Filter Housing
– You might have air in your fuel system which could cause issues with your fuel supply and fuel filter housing. Our technicians will search for a root of the problem at the fuel system and at the inlet and outlet of the fuel filter housing by using a vacuum test.
• High Pressure Pump
– After determining that the high pressure fuel system is not leaking pressure, we will take a look at your high pressure pump. Typically, your injectors will be affected first and the problem may end there but, if the high pressure pump has been significantly contaminated with dirt or water, we will have to replace it. You may notice a problem resulting from your high pressure pump when you are trying to pull an extreme load, such as towing a trailer uphill.
• Injectors
– Our expert technicians will take a look at your injectors to determine return flow and analyze whether it falls within the normal range for your engine.
– Your injectors may be leaking excessively which would result in a starting issue. If we notice either of these conditions, we can identify and replace the bad injectors.
• Turbocharger
– We will check your turbocharger for a spun camshaft bearing which would result in a turbocharger bearing failure.
– We will also have a look at your vane position sensor on your turbocharger to see if it is consistent with the desired position.
• EGR (Exhaust Gas Recirculation)
– Your starting issues could be resulting from a missing or improperly sealing EGR tower gasket. This condition would also cause excessive black smoke.
• Encoder Sensor
– A no start problem could be caused from a failed optical sensor, or encoder. We can disconnect the optical sensor and attempt to start your engine without it to determine if this is the root of your problem. Because the encoder sensor has to see through the fuel inside your pump, any air, dirty fuel, or dye in your fuel can cause a problem with it.
• Wire Harness Testing
– Of course, no start or trouble starting can be associated with poor electrical connections or wiring. If your problem is intermittent, this is a likely cause. We will examine the integrity of all wire harnesses to ensure that they are properly engaged and put together.

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We are determined, at Dallas Diesel, to offer the very best in diesel engine repair and services. Our technicians have years of specialized training in diesel engines specifically. We are here to help you with any problems that may arise with your Chevy Duramax. Call us today to set up an appointment.

Dallas Diesel’s Vehicle Specializations:
– Ford Power strokes
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– Chevy Duramax
Dallas Diesel’s Service Specialties:
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175 E Interstate 30 garland Dallas, Texas 75043 972-303-3003 Monday-Friday 8am-6:30pm Dallas specializes in Ford, Dodge, and Chevy diesel truck services from bumper to bumper: Full Engine Builds Repairs Performance Maintenance Trans Builds Suspension Builds   We install: Car audio and …
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