Tech Help

[jeanne]

We have a 2003 Sierra 2500 6.6L enging

We took truck back to dealer (3rd time) for problems with intermittent issues starting and power flattened out at higher rpm. This time we were told we had bad gas, they wanted to drain all the diesel (bought at Chevron).

 

Diesel mechanic at dealer said the diesel fuel sampled from my tank has an API reading (aka specific gravity) of 40 to 41 using his temperature adjusted hydrometer and that the GMC spec calls for a range of 34-39 for #2 diesel. The factory tech rep (?) is telling him he needs to drain the tank and replace with diesel that is w/in range.

 

My only issue with the truck is that the fuel rail pressure running at load is approx half of what it should be (approx 12k vs 26k psi) which is why it threw only the one code P1094 instead of both code for low fuel rail pressure at low AND high rpm.

 

QUESTION: Can the fuel density (+1-2 API) cause the fuel rail pressure ONLY at high rpm to drop in half?

 

We got the truck back and have been driving it, using up the fuel and saving the money it would have cost to have all the fuel drained out of the truck. I'd like to get this issue cleared up before I'll trust them working on my truck again. I did post this in another location in this blog before I saw this section with help from technician. I really appreciate your expertise.