Race Valve...

[TDFDiesel]

A shim increases the amount of pressure required to pop the FPRV and a race valve blocks the line.

In theory a shim is the "safer" way to go, but I've never heard of anybody having any issue either way.

[Blackcloud556]

I think the big fears came from several years back when stacking was big. CumminGs guys would use a box that added both pressure and timing, then stack a pressure box on top of that which could create dangerous rail pressures.

I like to think that Duramax guys are smarter then that. lol

[mcle6103]

Originally Posted by Cknight199

Will a breaker bar and socket fit down there, that seems like it would work...

And gm tends to over tighten stuff. I had to use a breaker bar to get my oil drain plug out!!


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You have to pull the bracket out apparently that the control module and its black sheet metal bracket are attached to. Then a socket will.

And yea honestly the only way I can see using a breaker bar is having someone hold the socket on while somebody else pulls, otherwise I see it just popping off each time and rounding it more and more.

[Cknight199]

So when do the trucks use the frpv? When defueling is it electronically commanding the truck to defuel meaning less pressure, or does it increase the pressure to let it blow out the rails? Sorry I'm new to the fueling and rails


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[Meyerperformance]

The FPRV protects the injectors from a high rail pressure spike. Like Jason said earlier high rail psi spikes were more common with guys stacking.

[Blackcloud556]

most guys run into issues with the rail popping off due to todays tunes which generally increase rail pressure. I dont think GM designed the engines with adding additional pressure in mind. so thats why lots of guys will start popping the rail and run into issues with simple tuners

[Cknight199]

Double
Post

[CaptPhil]

Originally Posted by mcle6103

How long did it take you to get your rail out? I feel that I may unfortunately have to do this...has anybody taken a rail out before and could give me a time frame? I haven't rounded the head off quite yet, I can get my wrench on there and pull with all I've got and it won't break lose. But the problem is half my strength goes to just holding the wrench flush on the bolt and not yankin on it at an angle. I fear it will end up rounding off in the end though, I started out using a sh!t cheap wrench I bought that day from autozone and it was crap and did a little damage to the head. Went and then bought a kobalt and it holds on strong but the 6" wrench doesn't give me enough leverage and I can't seem to get a configuration for adding leverage that won't cause me to just pull the wrench off the head due to some severe angle. HELP

I had the rail off and reinstalled in under two hours. I spent more time than that just trying to get the plug outn in the first place. Went in faster than it came out. I broke a craftsman wrench and a socket on it before I decided to pull it. Took my IR impact on full to get it moving. I was never getting it out otherwise.

[mcle6103]

Originally Posted by CaptPhil

I had the rail off and reinstalled in under two hours. I spent more time than that just trying to get the plug outn in the first place. Went in faster than it came out. I broke a craftsman wrench and a socket on it before I decided to pull it. Took my IR impact on full to get it moving. I was never getting it out otherwise.

Gotcha....dont think I'd actually tackle this job myself if it came down to it. I'd probably have a shop do it, but if you did it in two hours then I can't imagine a shop taking any longer

[DirtyMarx]

Spent a few hours this past weekend trying to get that bad boy out. Someday I'll get it haha!