Why is my Duramax fuel rail pressure so low?

This is a very common problem that we hear about from our Duramax customers. Actual fuel rail pressure is not keeping up with desired fuel rail pressure. This may only happen in high fuel demand situations like towing or racing but it can also happen with everyday use.

What should I do if my fuel pump is low?

The first thing you can do is to check the screen filter. The screen filter protects the fuel pump from dust and debris and can get clogged up pretty quickly. This can hinder the flow of fuel to the fuel pump and into the cylinders. So, it is better to clean the screen filter and replace it with a new one if needed.

What should the fuel pressure be on a Chevy Silverado?

If you want to save some bucks on this purchase take a look at my recommendations here: Where To Buy A Fuel Pressure Test Gauge. FUEL PRESSURE SPECIFICATION: The fuel pressure specification for the 1999-2006 4.8L, 5.3L, 6.0L Chevrolet Silverado (Suburban, Tahoe) and GMC Sierra (Yukon, Yukon XL) is 55 to 62 PSI. Flex fuel engines: 48-54 PSI.

How to test the fuel pump on a Chevy Silverado?

All of the following fuel pressure test gauge kits will help test the fuel pump on your Chevrolet Silverado (Suburban, Tahoe) and GMC Sierra (Yukon, Yukon XL): As I mentioned at the beginning, testing the fuel pump simply involves connecting the fuel pressure test gauge to the fuel system.

Are there any issues with the Duramax fuel pump?

The new injectors available from us and others are updated and do not have the cracking issue. Fuel Filter Housing Oring Leaks – The Duramax fuel system does not have any sort of low pressure fuel pump pushing fuel to the engine from the tank. The injection pump sucks all the fuel from the tank.

Where is the CP3 injection pump in a Duramax?

The CP3 injection pump sits in the valley of the engine between the cylinder heads and is driven by the camshaft gear, and it has two main jobs: get fuel from the tank up to the engine, and pressurize the fuel to 26,000psi and ultimately inject it into the engine.

What are the diagnostic parameters of a Duramax diesel engine?

2005 6.6L (LLY) Duramax Diesel ENGINE DIAGNOSTIC PARAMETERS SENSED PARAMETER FAULT CODE ACCEPTABLE OPERATING RANGE AND RATIONALITY PRIMARY MALFUNCTION DETECTION PARAMETERS SECONDARY MONITORING PARAMETERS AND CONDITIONS MONITORING TIME LENGTH AND FREQUENCY OF CHECK MONITORING METHOD FAULT CODE STORAGE AND MIL ILLUMINATION

Where is the CP3 on a Duramax engine?

This CP3 is under high demand, sucking fuel from the tank through the filter and then converting this to pressures up to 26,000 psi.It is a mechanical pump and does wear with use. This is a big job to do as the CP3 is gear driven off of the camshaft and is located in the valley of the engine.

Why does the P1093 code keep coming up?

Made it out of the drriveway and engine lost all power and I couldnt go faster than about 23 mph. Changed tunes to 1 Simon send ahile back (I have used before) and towed about 200 miles at about 5mpg (yeahh). For some reason I can not get this code to go away now and stay away. 3 diff tunes with the same result.

What are the P1093 codes for Duramax trucks?

9,659 satisfied customers 2005 chevy: duramax cranks but wont start,checked fuel filter 2005 chevy 2500 duramax cranks but wont start,checked fuel filter by opening bleeder on top as soon as i pushed prime ball,fuel squited out.truck dont even try to start. Codes p0700,p1093… read more jmbenedict02 22 satisfied customers

What are the error codes on my Duramax truck?

Codes p0700,p1093… read more jmbenedict02 22 satisfied customers have two error codes on my truck – chev duramax 6.6L p0203..rev have two error codes on my truck – chev duramax 6.6L P0203 and P1262 – anyplace to find what these codes mean? and is it just the truck going into safe mode – will not go out of @nd gear, and when I s…

Where is the valve on a Duramax Chev?

This valve is a small plug in the end of the drivers side fuel rail. When they get hot, the start to open a bit too soon and set this code. There is a cheap solution to this. A shim that will hold the pressure back. Here is a website that sells these shims. http://dmaxstore.com/index.php?main_page=product_info&products_id=93

What was the problem with my Duramax diesel engine?

It was logged while pulling an empty 24′ gooseneck. There is a marker about the time the error occur. The problem is finally solved. It was the ECM. Replaced it, flashed the same tune, updated injector data and its been running for two days now without a problem.

Is there an ECM signal to the fuel pump relay?

The fuel pump relay works as it should. I always have power to Pin 30. I believe the ECM tells the relay to work via the green/black wire to Pin 85. This should happen for 2 seconds when the key is turned on. I have tested this when the issue is occurring and have confirmed that no signal is being sent from the ECM.

What’s the low fuel pressure code on a Duramax?

Duramax LBZ and LMM P0087 Low Fuel Pressure code Summer comes, temps rise, and the working trucks with relatively high miles start to set a P0087 code and go into limp mode while towing. I am on the receiving end of continuous calls over the past few years inquiring what to do.

Why is my Duramax diesel engine not working?

The trucks computer keeps track of how much fuel needs to be added or subtracted from each individual cylinder to make the engine run smoothly, and this value is called the balance rate. If one cylinder is contributing too much or not as much as the rest, the cause is usually a bad injector and the cure is a replacement.

What was the code name for the Duramax in 2011?

In an effort to keep up with the ever-tightening emission regulations, GM redesigned its Duramax for the 2011 model year, and this time the code name was LML.

Why does my ECM say fuel to air?

Your engine is never as finicky about fuel-to-air ratio as it is when it’s first starting up. If your ECM is setting the ratio incorrectly, this is the first time you’ll notice.

How long does it take to repair a Duramax fuel rail?

Inspect the unit as well as the fuel tank and remove the offending particles or repair the separated pickup tube. Tools needed: fuel line quick disconnect kit, can be the cheap plastic ones sold at the local parts store. Approximate time is 3-4 hours. Cost: is less than $20.00 unless the pickup/sending unit is damaged.

How much power does a Duramax Diesel have?

Power was at an all-time high coming in at 397hp and 765 pounds of torque, and in order to provide this much power while still keeping pollutants low, GM needed to be able to increase the pressure in the fuel system to levels above what the tried-and-true CP3 could safely deliver.

When did GMC Duramax lose power under load?

In 2012 there was a P1093 code and the dealer invoice states “…low rail pressure during enrichment. Command high fuel rail pressure, pressure drops. Follow diagnostic chart, test system pressure, relief valve failed” so they replaced the FPRV.

What’s the Check Engine light on a Duramax?

Started up fine. Only thing i noticed was that the oil pressure was pegged out at 120 and the battery was around 10 or 11 marker on the gauge. Ran and drove fine. Keep in mind the temp was around 18F this morning when i left for work. You will need a scanner to pull the codes.

What is glowplug fault on GMC Duramax Diesel?

P133F is #8 glowplug hot resistance fault. Did you determine if the Elevated Idle is enabled? Are you using remote start? If not, are you giving waiting for glowplug light to go out before turning key to ‘start’? Elevated idle was not activated….it is now though.

How to diagnose p0087 GMC fuel rail malfunction?

Check the “Possible Causes” listed above. Visually inspect the related wiring harness and connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector’s pins. How much do you know about cars? The cost of diagnosing the P0087 GMC code is 1.0 hour of labor.

Why is my Duramax diesel engine not starting?

I have seen more leaks causing no starts, loss of prime and low fuel rail pressure codes from poor fitting aftermarket fuel filters use Delco only. Remember when dealing with power loss and fuel pressure issues the duramax has no in- tank or frame mount fuel pump pushing fuel to the engine.

Where does the fuel leak go on a Duramax?

Fuel leaks on a duramax are almost always on the return side of the system, the smaller of the two fuel lines traveling down the frame rail, going to the fuel cooler and back to the tank. They can leak at the cloth covered rubber return lines at the injectors, these lines can only be replaced in sets left and right side, they are expensive.

What happens when the fuel pump goes out on a GMC Sierra?

There are physical signs that you can feel when your Sierra’s fuel pump is going out. Before taking anything apart, check to see if your engine’s computer has any trouble codes saved in it. The engine may throw a P0087 trouble code. This trouble code detects that the fuel rail/system pressure is too low.

What should the rail pressure be on a Duramax LBZ?

The dealer can use his Tech 2 scan tool to control the injection pump and increase desired rail pressure to max of 160mpa at idle. The observed actual pressure should follow desired or at least be quite close. If not then step 3 is necessary to eliminate the rail pressure relief valve as a possible leak. Step three: Bottle test.

What should the pressure be on the fuel rail?

With engine running, observe the Actual Fuel Rail Pressure parameter with a scan tool. A normal reading would be approximately 40 MPa (5,802 psi) with the engine cold, and 30 MPa (4,351 psi) at operating temperature. Inspect the fuel supply lines for damage between the fuel tank and the fuel injection pump.

What should vacuum pressure be on Duramax diesel engine?

Attempt to start the engine. ⇒ If the engine does not start, refer to Engine Cranks But Does Not Run . Install the J 44638 to the fuel rail service port and slowly increase the engine speed until reaching wide open throttle (WOT). Vacuum should be less than 5 inches Hg of vacuum.

What is the proper fuel pressure for a Duramax?

Use common sense safety practices when servicing any diesel system: While maximum control oil pressure on a Power Stroke can reach nearly 4,000 psi, the Duramax fuel system is pressure-relieved at a blistering 27,550 psi. Cracking a fuel line loose on a running Duramax engine could easily be fatal.

What causes low fuel rail pressure?

Some of the most common causes of low fuel rail pressure can be a dirty fuel filter, leaking fuel filter head or a cracked water separator, a weak fuel pressure relief valve, a collapsing or cracked fuel line, a blocked or broken fuel tank pickup, or a sign of fuel delivery trouble.

What is the normal fuel pressure at the rail?

For a GM, this pressure is usually set to 58psi (factory fuel pressure in the rail). The vacuum/boost referenced regulator will help to change the pressure in the rail based on the pressure in the manifold. When an engine is idling, it may be pulling 20 inHg of vacuum, which translates to roughly 10psi.

What is a Duramax lift pump?

Whether you own a Power Stroke, Cummins , or Duramax-powered rig (or something else altogether), a lift pump can simply be defined as a low-pressure supply pump that is used to transmit fuel to a high-pressure pump. In the case of most mechanical engines, fuel pressure is fed to an injection pump,…

Can a low fuel rail pressure cause a Mil?

Low rail pressure may or may not cause an MIL (check engine light). This is a very common problem that we hear about from our Duramax customers. Actual fuel rail pressure is not keeping up with desired fuel rail pressure.

How does FRP sensor work on Duramax diesel engine?

The FRP sensor uses a 5-volt reference circuit , a signal circuit, and a low reference circuit to monitor fuel rail pressure. This information is sent to the engine control module (ECM) to assist in the fueling of the engine. • DTCs P0090, P0192, P0193 are not set.

What are the symptoms of a bad Duramax fuel regulator?

Common Duramax Fuel Pressure Regulator Problems 1 Black Smoke. As we’ve said before, one of the most common problems that fuel pressure regulator experience is black smoke. 2 Strong gas smell. What are some of the most common symptoms of a bad fuel pressure regulator? 3 Hesitation on the gas pedal. 4 A decrease in power acceleration.

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