Fuel Rail Race Valve - Possibility of Damage?? Etc.

[2003DMAXCliff]

I have been reading about the 'Race Valves" that a lot of places sell, but I have some questions before installing one on my 2003 LB7.

If the factory setup uses the Bosch Pressure Relief Valve to stop over pressuring the fuel rail, what happens to the "safety" factor when you put in a "race Valve" which to me looks like a it's just a plug with a very good seat ground\polished on it to stop any leakage. Why does the factory use the relief valve if it can be safely removed and there aren't any issues with the fuel rails, fittings, fuel lines, the high pressure pump, etc. being hurt???

Also, I see talk of "Shimming" the original valve. What are these shims and how do they help? Where do you get them? I don't understand exactly what that is or how it helps.

I've read that once the factory fuel rail pressure relief valve "pops", It's hurt and will always allow pressure blead-off.

Also, if it has "popped", doesn't that prove that such a relief valve IS necessary to protect the entire high pressure fuel rail system and\or high pressure pump??

Sorry for my ramblings, Just a bunch of concerns that I would like to have answered before installing a "Race Valve" and doing a lot of expensive damage!! And I also find it interesting that there aren't a bunch of places for sourcing replacement OEM Bosch Relief valves.

Side Note - I put one of the DMAX store rebuilt transfer cases with the new upgrades into my old 200.000 mile Chevy and I think it's better than the factory original ever was!!

[DMAXDR]

The use of a "race valve" just like other aftermarket parts that are designed to alter the design intent of a engineered system, does come with some risk. The relief valve is used to relieve fuel pressure above the maximum designed threshold, or fuel pressure spikes. The unfortunate side of the factory relief valve is is that they will become weak after repeated use . This will result in low rail pressure codes, performance loss, and limp modes. The rail plug is necessary when demanding maximum performance from the fuel system . Fuel system components can fail with a fuel system that is in stock form as well as highly modified. I have built many truck that have been running race plugs for years under all types of conditions and can't say that this part has been a cause to a fuel system failure.

Very good to here that you are very happy with the t-case !!!

Hope this helps

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[DMAXDR]

To touch on shimming the relief valve. The shim kit is used to create more seat pressure causing a higher relief pressure. The relief valve is disassembled and a shim is added in between the internal spring and valve seat. This modification will still allow some pressure relief. This is available for LLY,LBZ,LMM.

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