[KingLT1]

Originally Posted by Sillysspeed

we used to always just put a bigger intank pump in. Most recently on my 4th Gen I had 1 450 walboro in tank and then went turbo and added another. In this car people want you to add a lt4 in tank (don’t know rating) and then add a jms booster on top of that. Why not just do a 450 or 525 in tank?

To keep the voltage consistent to the FSCM. Gen 5 LT stuff has variable voltage system so the voltage to the fuel control module(FSCM or CCM depending on year) sees different voltages. Even if you did just a drop in larger fuel pump in the tank, I would still run the JMS. That way you can let the system work as intended under normal use but always ensure that the fuel pump gets the same voltage under wot. Now there are things you can do in the tune to lock the voltage at a fixed voltage but that wasn't how it was designed so I prefer to use the JMS for that reason.

[Sillysspeed]

Ok that makes sense. Thanks for that answer

[asthmamax11]

Originally Posted by KingLT1

To keep the voltage consistent to the FSCM. Gen 5 LT stuff has variable voltage system so the voltage to the fuel control module(FSCM or CCM depending on year) sees different voltages. Even if you did just a drop in larger fuel pump in the tank, I would still run the JMS. That way you can let the system work as intended under normal use but always ensure that the fuel pump gets the same voltage under wot. Now there are things you can do in the tune to lock the voltage at a fixed voltage but that wasn't how it was designed so I prefer to use the JMS for that reason.

Man I really appreciate you always being so generous with sharing tips and info.
It's really encouraged me to keep this build going

[Evansa22]

Anyone ever seen a jms burn up a lt4 pump? All of a sudden my lowside is dropping pressure WOT when it was fine before at same boost level. Voltages are correct, as well as ramp in.