I have my fuel pressure gauge after the filter and the ksb is on a switch, when its on I lose 1 psi.

I thought that the ksb worked by increasing pump pressure by reducing return flow, but that should show an increase on the gauge.

Whats the deal? am I thinking wrong or do I have a problem with the return regulator? The truck can suck the gauge to 0 with stock injectors and a year old diaphram lift pump so I need all the pressure I can get until I upgrade the fuel supply.

 

Seems like I noticed something similar in my D350 when I put the KSB on a switch.

If you can suck yuor fuel pressure to"0" with stock injectors, you need to update your supply lines- go to at least 3/8" hose frmo the tank to LP.

 

your loosing fuel pressure going into the pump because your flowing more fuel. The KSB increases pressure INSIDE the pump, which flows more fuel going out of the pump and makes more power.

More power=more fuel.
More fuel=lower pressure from the LP and filter because they dont flow enough to keep up the same PSI.

 

is it bad to run the case pressure switch all the time?

 

I've heard it can heat up the injection pump and wear it out from some people and others have told me they run it all the time and have for years with no problem. So I guess its somewhat up in the air as to weather or not running the KSB all the time will damage the pump. Thats why I just did the WOT switch, so anytime I go WOT it is on and normal driving its off. I do want to take my IR Fluke camera and see if the pump case is any hotter with the KSB running for long periods of time, just so I know for sure if there is even a chance.

 

When I hit my ksb switch I can watch my case pressure jump from 80-100psi to 190-200psi or more sometimes it just hangs out on the 200psi pin. When I lay on the throttle i can watch it go down to around 140psi+/-

When I had my pump on the test stand I didnt really notice anymore flow in fuel. I think most people gain hp from the advanced timing not a gain in flow.
I dont run mine all the time.

NO_SPRK You ever make it to Eureka?


Stomp

 

So what does the ksb do inside the pump to increase the pump pressure?

I read in another thread that Dave said "It gives advanced timing at idle by closing a pressure regulating valve, increasing the case pressure"

Can anyone give some more detail on what the valve does?

Or maybe I should ask a different question, does everyone else see a drop in fuel pressure going into the pump with the ksb on or not? And it doesn't matter if I'm driving with the gauge at 3-4 psi or if its idling at 5 psi I still lose about 1 psi when the ksb is on and it bugs me.

 

That was an oversimplification. The case pressure is controlled by a spring loaded spool valve that recirculates fuel from the vane pump outlet back into the inlet. When the KSB is "on", case pressure is applied to the spring end of the spool valve, effectively holding it closed and preventing recirculation.

It puts a lot of load on the vane pump, which is why it's probably not a good long term plan.

That said, I know many non-intercooled trucks have run for years with the KSB activated because the wire fell off. Also, intercooled trucks run in KSB mode most of the time in cold weather highway driving.

 

Thank you.

Thats what I wanted to know. So I am losing pressure because it isn't recirculating the fuel. One less thing to worry about.

 

yeah. i actualy went to fortuna but i went up to eureka to get my girl a present from the humbolt store. i stopped by ponci's and asked him some questions. he had some nice trucks there. i should be going back up there soon to bring a car up. maybe we can meet up and shoot the edit