Need help trouble shooting

Jim Fulmer

Jim Fulmer

New member
I don't know squat about a duramax so I thought I would ask you'll.

Have a friend with an 06' and I'm guessing LBZ, the truck is an auto and with 300K on it, the issue he is having is running down the road with a 8K trailer (a load has to be one it....not empty) the truck will loose power so he pulls over, shuts it off for 2 min and it runs great again for 80-300 miles then does it all over again. It pops a low rail pressure code!

Problem is the only help he had was from the dealer and they pump an injection pump.....didn't change anything but they sure charged him, then they wanted to put injectors in to the tune $5000......he said no! He took it to a individual and the doesn't think they put a pump on it but he will be able to tell later, he is looking at two valves that can go bad.

Any sugjestions were to go next?

Jim
 
I wonder if the FPRV(fuel pressure relief valve) is bad. If it developes a leak after being under pressure for a lengthened period of time due to a weak spring, it would cause the problem you are describing. He could try the bottle test. Basically you take the line off of the valve and instead of it going back to the tank, put it in a bottle under the hood(securely fastened obviously). When the problem occurs, if there is fuel in the bottle, then the valve is bad. Cheap fix too by the way. I doubt injectors is the problem since it runs fine most of the time. Usually injectors will cause poor performance at all times.
 
if you typed correct and the truck has 300K on it I would suspect a FPRV gone bad. Do a bottle test and if you get fuel might aught to consider a PPE race valve. with that many miles a shim would be useless I think
 
Location Tuttle Oklahoma!

Nope he bought it new and hot shots with it, he bought another new one and kept this one as a backup and a farm truck.......no one has figured it out yet but the stealer put a pump on it.....no joy, then they wanted to put injectors in it.......that's good trouble shooting, throw parts at it till it's fixed.

Jim
 
Read the rail psi while driving down the road. See if you can see the rail psi actually drop when the problem starts. If so, start checking return fuel amount. Double check my math but i think it is 6 oz of fuel in 1 minuite at idle.
 
Sounds like the FPRV. It's located on the rear of the drivers side fuel rail. Once they start popping regularly, they can groove the rail also. So if replacing the FPRV does not work, then a new rail is most likely in order.

Best thing is to run a bottle test, this confirms if the valve is leaking.
 
John Robinson said:
Read the rail psi while driving down the road. See if you can see the rail psi actually drop when the problem starts. If so, start checking return fuel amount. Double check my math but i think it is 6 oz of fuel in 1 minuite at idle.
Click to expand...


x2, injector(s) could be the culprit
 
dont get mad at me but my instructors always say automotive guys are just part changers it takes a really diesel tech to do the job right dealerships suck. thats coming from a guy that has worked at a dealership for 20 years or more and he says dealerships just want the truck out there shop change a part and make money.
 
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