Rail pressure drop/spike after cp3 conversion

[nick31]

had a cp3 conversion done and since then my rail pressure has been all over the place @ idle. Dropped as low as 3.8kpsi and spikes up to 4.8kpsi. Normal driving seems okay. Logged it PPEI said nothing looks out of ordinary.....

everything done to the truck is in my sig. balance rates on injectors are perfect. my fass goes straight to the cp3, stock hard line and factory filter housing are gone. not sure where else to start. no CEL's. Seems to only do it when the truck is at operating temp. Never had this issue before doing the sportsman conversion.

For reference......https://www.youtube.com/watch?v=zprHojxC6PQ

 

[plowboy_lbz]

Fuel pressure fass is putting out? On my lbz anything over 12 psi and rail pressure gets jumpy. Are you checking this with motor warm?

 

[nick31]

yes motor is warm when my rail is all over @ idle

not sure on the fass I don't have a gauge on it, i'll pick one up and see whats going on with it.

 

[kiwilml]

I can be over 15 on my fass and it don't affect my rail pressure.. I guess you could disconnect it for a minute and see if that fixed the issue though..

 

[FC5452]

What's the one on the middle right looking at? The desired? If so, it's calling for that and your getting spikes and fpr#2 ( the relief) is being regulated and adjusting. Check your Lift pump pressure I was at 15 psi and dropped it to 12 at idle and I'm fine.
Nothing is stock on my fuel system either.


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[nick31]

middle right is desired, right at 4.4 always like it should be top is actual frp. ill check fass pressure and see if spring needs to be trimmed