LLY: P0088 pump or regulator ? [Archive] - Duramax Diesels Forum


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11-23-2011, 06:14 AM
My lly will thro a p0088 code and defuel. Ive got efi dsp on the edge cts monitor. I can clear it out and it runs fine. I pulled home a truck on a trailer Sunday and the stock tune was the only one that wouldn't thro the code. The load was at around 45-60% on the monitor and I wasn't pushing it hard. Just cruising at about 65-70. The code on the edge says rail pressure too high. When cruising at that speed it was around 22-24kpsi. Any ideas or help is appreciated.

11-24-2011, 05:11 PM
i would think regulator would be the problem before the pump. usually if the pump goes bad it doesnt supply enough rail pressure and you get low rail codes. if its making to much pressure it would have to be the regulator.
does the truck lobe really bad at idle or sound louder? (injector/fuel knock noise)