Do you think that an emulsifying additive caused my fuel pressure regulator to start failing? I have the lopey idle.

This is from the TSB for the replacement of the reg. Read the line about additives...

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Info - 6.6L LB7 Duramax Diesel Fuel Pressure Regulator Replacement #03-06-04-010 - (01/17/2003)

6.6L LB7 Duramax™ Diesel Fuel Pressure Regulator Replacement

2001-2003 Chevrolet Silverado 2500/3500 Series Models

2003 Chevrolet Kodiak C4500/C5500 Series Models

2001-2003 GMC Sierra 2500/3500 Series Models

2003 GMC Topkick C4500/C5500 Series Models

with 6.6L Duramax™ Diesel Engine (VIN 1 -- RPO LB7)

The fuel pressure regulator, P/N 97728979, is now serviceable separate from the fuel injection pump.






If the Service Manual diagnostics lead to the replacement of the fuel pressure regulator, inspect the inner tip of the regulator (see illustration) for corrosion upon its removal. The inner tip of a fuel pressure regulator from an uncontaminated fuel system will be smooth with tan colored fuel deposits, but it will not be blackened with heavy scaling or pitting.

If blackened corrosion and pitting is found on the inner tip of the regulator, the integrity of the fuel injection pump has been compromised and the pump must be replaced. Replace the fuel filter element and clean the fuel system using Service Manual procedures. Injector replacement is not necessary, as the fuel injection pump is the most susceptible component to corrosion damage. After repairs are completed, re-evaluate the vehicle's performance to ensure no additional concerns are present. Some fuel additives emulsify water into the fuel and allow the water to get past the fuel filter/water separator. Fuel additives can be introduced by the customer or by the fuel retailer. Advise the customer of possible fuel source issues and recommend against the use of aftermarket fuel additives.

I have had my lopey idle since new...day one. Since using Primrose I only see the lopey idle when the compressor is on....for some strange reason.

Normally I got it cold or after coming off the freeway..but those conditions are gone since using the additive.

So I would say the additive reduced the lopey idle in my truck but did not completely eliminate it.


BTW: the dealer put in Standyne additive to 'fix my lopey idle' when the compressor was on. It still did it. Now I will ask that they replace the damn thing.

Yeah my compressor makes it worse.......

I would imagine that it's possible. I mean, everybody thinks that GM is in bed with Stanadyne and that's why they recommend it. Personally, I think there is some seal susceptibility when using emulsifiers.

But that's really a lame answer. I think the real reasons are that some components in the injection system don't like to be exposed to the particular hydrocarbon make-up of the emulsifier additives and that the entrained water probably will have bad or weird effects to the system. The seals of anything are the most susceptible

We really need a GM fuel systems engineer to chime in on the short and long term effects of different additives and what are the bad effects of encapsulating water entrainment on HPCR systems.