2006 lly c5500 help!!!

I have a 06 C5500 keeps tripping P0087 code Low Fuel Rail Pressure. I have replaced the injectors, fprv, and fuel supply hoses from the tank, and the fuel filter several times. I was told I could delete the P0087 with a efilive controller and my truck would be derated slightly but would not go to limp in for the low fuel pressure. I have spent $7000 dollars on truck and can't get rid of the P0087 code it occurs after engine reaches operating temp and will go to limp in under load on any hills or a strong head wind. I need some advice thanks.

Have you made sure your fuel cooler is good and clean so that it can cool the returned fuel? I would reccomend installing a lift supply pump like the KENNEDY kit close to the tank first. I know some have said they have resorted to installing an extra fuel cooler out in front of the radiator to keep the fuel cooler and denser resulting in better fuel pressure holding.

ok well does a C5500 chassis have a fuel cooler? noone has mentions this before so i'm ignorant on the subject.....it does make sense though cause it won't do it on cooler mornings untill the temp comes up

Have you considered logging the actual vs desired FRP? Fuel temp also. If there is a correlation with underhood heat, then look at hardare, hose sucking closed possibly too close to exhaust manifold, etc. The easiest cure for that kind of thing is a larger line.

Or as suggested, a low pressure lift pump to reduce the suction in the line.