Lmm Dead At Fuel Pump

[snowsporter]

i have a 2007.5 with the LMM. been running it a little hard since i bought it a few months ago, roughly 13000 miles in and 4 months. today i pulled in at the fuel pump and shut it down to refuel. that was the last breth it took for today. WIF light has not been on and the DIC is showing about 51% for fuel filter life. all fuses checked out good with a test light and it the fuel fitting off the rail had no fuel. is there a problem with the fuel pumps or is this just a fluke?

[DmaxMaverick]

Did you try priming the filter? If not, pump it up until you can't. It may have got a slug of air, or you may have a fuel leak somewhere. If you can pull DTC's, it would be helpful if the priming doesn't work.

[snowsporter]

if it did get a slug of air, hor do you prime the filter for future reference. i'm used to shipboard diesels that are self priming by turning the engine over for a while which is what i was doing after pushing it away from the pump.

[Runaway_Dmax]

Drivers Side of engine is where filter is located, on top of filter housing is a pump. You can loosen the bleeder screw (also on top of filter housing)and you will see fuel come out of the bleeder screw when the filter housing is full. Be careful if you decide to take the bleeder screw out as these are hard to come by if you loose it.. Also be careful when you tighten it up. Just snug works. ;)

[DmaxMaverick]

Thanks, Runaway. Yes, you can open the bleeder and see the fuel (or lack of it). But, just opening the bleeder and pumping only fills the filter. After you have fuel at the bleeder, it needs to be closed and pumped up until hard. This will prime the pump. Your system does not have a traditional lift pump. The system is suction from the tank to the fuel pump on the engine. It is not self priming, so it needs help if it loses prime. Another possibility for a fuel leak is a loose filter element. These should seal well hand tight or slightly more. They can loosen from engine vibration, and a plugged filter due for service exaggerates the leak (greater vacuum).

True about the bleeder screw. It is plastic, and often difficult to source. I suggest using a nut driver or socket for loosening/tightening. Many uses with a screwdriver may crack it. If it leaks due to being cracked, your system won't maintain prime and suck air. A little air will cause the symptoms like you saw after fueling. A large leak will stall the engine, and no amount of priming will help. If you need to replace it, Greg Landuyt (http://www.lubricationspecialist.com) (TDP supporting vendor)offers a stainless steel replacement (straight slot and knurled, not hex) that's pretty nice. When tightening the screw (plastic or SS), it only needs to be finger tight or slightly more. It's O-ring sealed.

[snowsporter]

thanks for the information. this is my first diesel truck some of hte little quirks i'm still getting used to. as of this morning the truck was towed to the stealer to get looked at. from the diagnosis this morning they think its the fuel pump but we'll see whenever i get it back. the stealer made it sound like there is a fuel pump in the tank like a gasser. will find out more monday. will post the results afterwards.

[DmaxMaverick]

If they think there's a pump in the tank, find another dealer. Unless someone put one there after the factory, there isn't one. The fuel system is suction all the way to the pump in the engine valley.

The Duramax vans have an aux. fuel pump for priming due to the location of the filter assy. It doesn't run during normal engine operation. It's not located in the tank, either.

[snowsporter]

after getting the vehicle into the shop they determined it was a fuel problem not a pump problem. they put a vac guage on the fuel rain and it was pulling almost 9 inmg when the max is around 5. sounds like i got slammed with some bad fuel somewhere. anyway 200 bones for labor and replacing the fuel filter. runs like a champ now. i'll check fuel mileage on way to florida and back. will be empty down and about 2k in the bed on way back. will keep posted on mileage

[Kennedy]

If you put 13k on the same fuel filter then that is not unexpected.

[snowsporter]

you are right kennedy. i should know better and use the hour meter to monitor how long the engine is actually running. i work on larger ship board diesels and the filters are changed about every 250 hours not by miles. i looked at the hour meter after it wsa back and i was pushing the 300 hour mark. i am going to keep a couple of filters on the shelf and change them around the 250 mark to eliminate this from happening again. i still had the mindset of 30k for fuel from my gasser so that is the first thing to change. anyway, got to florida without any issues and averaged 19.5 hand calced for the 1000 mile trip. just could not push any higher than that. we'll see going back up with a load in the truck