A common problem with high-mileage Duramax trucks is that the fuel filter head assembly begins to develop air leaks. With age as well as use of ULSD and bio-diesel fuels, the O-rings in the filter head assembly can begin to allow air to bleed into the system, causing the fuel system to loose its prime.
Early signs of a leak include extended cranking after the truck has been sitting for long periods as well as the engine starting and then dying. As the problem worsens, it may become impossible to restart the truck without manually priming it when parked on an incline. External fuel leaks can develop as well, and will be evidenced by fuel puddles on the ground or on top of the filter assembly. Your GM dealer will most likely suggest replacing the entire assembly, but the team at Merchant Automotive has better and less expensive solutions: they have developed several repair kits that require only hand tools and basic mechanical skill.
Remember, this is an overview of the process; if you have questions about the specifics you can consult the team at Merchant Automotive or your local diesel performance shop. You can also watch a video of the process on the Merchant Automotive website. If you plan to rebuild the filter assembly yourself, set aside a couple hours and be sure to practice safe shop techniques. After rebuilding and reinstalling the filter assembly you will need to prime the fuel system before starting the truck.
Prime the system by pumping the primer plunger repeatedly until it becomes firm, and then start the engine. After starting, make a thorough check for fuel leaks before driving the truck. A billet aluminum bleeder screw replaces the factory-installed plastic bleeder screw, which is flimsy and prone to stripping and cracking.
All of the billet aluminum parts are anodized black for durability and good looks, and they feature a laser-etched MA logo. You can rebuild your fuel filter assembly without the billet parts, but we think the full kit is a wise investment.
Phaff removed the filter assembly, rebuilt it and reinstalled it in about an hour, including our typical photography slowdowns. Follow along over the next few pages to see the basics of Phaff rebuilding the filter head assembly. The filter assembly on this truck was not leaking fuel externally, but it was allowing air to bleed back into the fuel system causing the CP3 to loose its prime. The truck would not start unless the fuel system was manually primed.
Jake Phaff began the installation by removing the passenger-side intercooler tube to make it easier to access the fuel filter assembly.
With clear access to the fuel filter assembly, Phaff loosened the spring clamps on the fuel lines and slid the lines off the fittings. Moving to the wheel well, he removed the fasteners from the forward portion of the inner fender liner, and then pulled the liner back to allow him easy access to the underside of the fuel filter assembly.
Both the water-in-fuel sensor harness and the fuel heater harness must be unplugged before the filter assembly can be removed from the engine. With everything disconnected, Phaff was able to unbolt and remove the complete filter assembly from the truck.
Looking at the water-in-fuel sensor harness, it was obvious that it was ready to fail see arrow.Law enforcement training conference 2020
In fact, when positioning the harness for our photos, the corroded lead actually broke away from the sensor. Before rebuilding the head, the filter and WIF sensor need to be removed from the head.Forums New posts Search forums. What's new New posts New resources New profile posts Latest activity.
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GM 6.6 Duramax diesel tips for fuel system diagnosis
LLY--Fuel leak from engine-return lines?
Thread starter Dieseldad97 Start date Jul 3, Dieseldad97 I now know why. Got a pretty good fuel leak from the drivers side if the engine. Everything from the engine back is wet including the rear bumper haha. Could this be a return line issue?View Full Version : Lb7 fuel rail info.
Here is what i found I put them in a pail of carb cleaner last night to clean them up pulled off the fuel rail fitting and thought that was the biggest restriction Boy was I wrong:eek: Now im not sure how much difference if any there is in the lb7 fuel rails but this is from a I drilled mine out to about 60thousands Do we even need the orfice?
And does a lly have this orfice? On the dual feed line kit they let that hang and just plug the hole. If I remember correctly. That is what cured my dually on my last power issue. I was thinking about you when i did this Deejay there was a lot of little crap inside the rail:eek:.Personalized gift qatar
I think its there to control surging from the CP3, but don't quote me on it. I noticed a difference when I drilled it out. When I took mine out to inspect I saw no debris. When I drilled them and reinstalled it ran its ass off. I'm still not sure why. I also wondered if opening the holes in the fuel junction block just a little would make a difference or not. I do have a spare. Would you have to be careful as to not make it to big.Melodica anime songs
Like water in a funnel. Basically what I'm trying to say if we open the lines up closer to the injectors will it hurt flow? Or should we do this closer to the CP3? Or do this at all? Did that make sense?
What it the point of the PPE fuel rail inlet?Kanawha county school bus schedule 2019 20
Duel cp3s as far as I know dont have a orfice as you just pull the plug out of the back of the rail and run a line into it and they dont surge. Dammit guys, sounds like I may have more work to do LLY's have that small orifice built into the fitting, where as the LB7 has it seperate. I suppose so Simon if there is a seperate orfice restriction downstream from it.
They also had a custom gtMike L. Originally Posted by saint. I have also seen a few injection pumps leak, and the fuel run down the back of the engine, down the bellhousing.
Originally Posted by rgullett Get a flashlight, and pull the resonator off the top of the motor. You will most likely see a puddle of fuel in the valley.
Talk to the previous owner, and find out if they worked on any of the HP side of the fuel system. The LB7's have probably 20 or so unions that could be the potential culprit.
If Injectors, or the Y bridge, or CP3 have been pulled recently, they would have had to loosen at least a couple of those unions. Good luck. Its deffinatly comming from somewhere above the tranny and running down all over the place. Shouldn't have to take the turbo off I would bet it's the relief valve or r. If it's on the intake runners it is the injector lines.
Originally Posted by sweetdiesel. ChevyTruckGuy78's Garage. I say it's the fuel rail pressure sensor. Probably leaking the LB7's are known for it. You might get lucky and just be able to tighten it.LB7 DURAMAX INJECTOR RETURN LEAKS!!
All times are GMT The time now is PM. Mark Forums Read Who's Online. User Name. Remember Me? Page 1 of 5. Thread Tools.If you have a Duramax 6. Over the years these trucks have been really good performers, but they do have some common problems that we see over and over again. The original injectors that came in these trucks had all sorts of issues with cracking.
The symptoms are constant smoke at idle and gaining fuel in the oil. Unfortunately the best thing to do if you have this problem is to replace the whole set at once.
Injector replacement on the LB7 truck is rather labor intensive and just changing one is usually not worth the risk for the labor costs. 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. While we are seeing more and more rusted out fuel lines causing the engines to suck air, nine times out of ten the issues are in the fuel filter head.
Under the primer button there are some orings that fail on a regular basis.
DIY Duramax Fuel Fix: Rebuilding A Leaky Fuel Filter Head
This can produce long cranks and hard starts. Glow Plug System Issues — Nearly half of the check engine lights that come in for the Duramax pickups are for glow plugs. The glow plugs burn out over time and can be a real nuisance to remove from the aluminum heads sometimes. Not only does the threaded metal part of the glow plug seize in the head, but the tips of the glow plugs sometimes bulb making it really difficult to get them out.
Also the metal strips that connect the glow plugs together on each side corrode and break causing issues. Lastly we replace a fair amount of glow plug controllers as well. You will usually get a diagnostic trouble code for the cooler when they go bad. Head Gaskets — As these truck reach themiles we are seeing more and more head gasket issues. The Duramax has a multi-layer steel head gasket. When they have issues, they do not typically smoke out the exhaust or get coolant into the cylinders.
What happens is the head lifts a little during the compression stroke. This allows the layers of the gasket to separate which lets combustion pressure into the coolant system. The pressure will cause the coolant to be pushed out the coolant overflow. You can check for a head gasket issue by squeezing the top radiator hose when the engine is running and right after you shut it off. You should be able to squeeze the hose very easily. If it is rock hard, you have a head gasket issue.
It is extremely important to have the heads surfaced flat before putting the truck back together. This one is fairly common and unfortunately a huge pain in the butt to change.
Water will seep from the underside of the pump. Be prepared though because you will have to remove the dampner pulley to get the pump off. The pulleys are pressed onto the crank and you will need a really good puller to get it off.I've had a PPE dual fueler kit on my truck for awhile now and the other day at the grocery store i noticed a fuel odor coming from the truck i went in came back out and saw a small puddle under the truck got home and searched for awhile and figured it was coming from the drivers side fuel rail pinpointed it to the fitting at the end of the rail for the dual fueler took the line off to try and tighten the fitting its as tight as i can get it put the line back on ran the truck and still leaking its driving me insane has anyone else had this issue or have a solution for me?
JD Dave. Is it coming from the adapter or the line fitting? I had to tighten then heck out of my adapter to get it not to leak. Also the oring wasn't a common size, your sure it was the right one? I put a little fatter one in and mine leaked. Originally Posted by JD Dave. Let me know when they go up for sale. Originally Posted by xtremebikr If I remember correctly when i put the dual cp3 on my lbz you dont use an oring on the adapter fitting on the back of the driverside fuel rail.
LBZrcks's Garage. Originally Posted by LBZrcks. Pushing the D to the MAX D-MAX Mafia.
Dads truck leaks right out of the top of the drivers side rail the pressure relief port. Had to install a catch can to keep from dumping diesel everywhere. On the Droid X. If its leaking out of the port then the issue is either The fitting is not tight enough, the seat on the fitting is damaged or the inside of the rail is damaged.
All times are GMT The time now is PM. Mark Forums Read Who's Online. User Name. Remember Me? Page 1 of 2. Thread Tools. RichLMM Hotrodder. Find all posts by RichLMM. JD Dave In way over my head. Find all posts by JD Dave. Quote: Originally Posted by RichLMM I've had a PPE dual fueler kit on my truck for awhile now and the other day at the grocery store i noticed a fuel odor coming from the truck i went in came back out and saw a small puddle under the truck got home and searched for awhile and figured it was coming from the drivers side fuel rail pinpointed it to the fitting at the end of the rail for the dual fueler took the line off to try and tighten the fitting its as tight as i can get it put the line back on ran the truck and still leaking its driving me insane has anyone else had this issue or have a solution for me?Many owners can brag about 2 and mi service with very few if any issues.
But as with any mechanical thing some do have their problems and I wont try to cover all of them right now but I want to give a few pointers you should keep in mind before going to battle with one. As a result of my informal interviews,the Duramax diesels are not a big favorite of most mechanics. They are awkward to work on, anybody that has done head gaskets, injectors on the earlier design, turbos, broken glow plugs,gear drive water pump,front and rear main seals,high pressure pumps, replaced a fuel filter or any driveability diagnostics will tell you they are not a favorite to work on.
Their success as a design means mechanics dont see too much of them and dont get extremely used to them as they would ,say a 6.Simple webdav server
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.
The mechanical h. I have had many rotted fuel lines sucking air causing stalls, no starts, low power etc. Look at the lines first. Sometimes you will replace a fuel filter and will be unable to prime the system,you will pump the primer on the fuel manager fancy G.
This is either because you are out of fuel, you have a rotted line or the primer pump is bad. 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. You can open a can of worms trying to replace the return lines at the injectors, the lines snap into the injectors with plastic tees that love to break off in the injector,I have had luck heating a screw and melting it into the broken piece for extraction.
I usually disassemble a new line set and replace only the leakers individually. You will notice a hydraulic style fitting at the front right side of the engine, this is for a fuel pressure gage to test the suction side, good luck finding a fitting to snap on to it,I had to get a Kent Moore gage for bucks,I use it all the time as well as a Tech 2 scan tool.
I consider these a must for serious Duramax work. Well ,tune in later and we will discuss no start hot problems and shortcuts to solving injector leakback issues. Home Ford 7.
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