Fuel Pressure Trigger

[LTb1ow]

Kinda curious about which method would result in a smoother transition.

A) Hobbs switch on intake pressure, higher boost kicks on second pump

B) Fuel pressure sender on main fuel line, low pressure kicks on second pump

Reasoning behind your pick is prob more important than the pick itself.

[WildBillyT]

I think a Calvin switch would be the ultimate.

But based on my limited knowledge, and your two choices, I'd go with the Hobbs switch as the low pressure condition would not have to come in to play in order to get the extra fueling.

JMO.

[LTb1ow]

Well if I never encountered a low fuel pressure situation, why should I kick on the second pump?

Fuel system volume is not changing, so if fuel pressure is constant without dropping, why the need for the second pump to kick on. I assume its to make sure that when you elevate into higher boost levels you are already making the added fuel flow for when the motor guzzles more down.

Assuming thats a correct analysis, I guess the hobbs switch gives you more of a cushion of time for pump to kick on than a fuel pressure switch, which would be as soon as the motor demands more.

But, you are right, a calvin switch is prob the best.

[sweetbmxrider]

You should have a low pressure switch for spark retard or something. I would use the boost activated pump because you could have your main pump fail, it kicks on second pump, you unknowing of this go wot, and you don't have enough fuel. With it only kicking on in boost, you should notice a fuel issue out of boost before it could become an issue.

[LTb1ow]

Originally Posted by sweetbmxrider

You should have a low pressure switch for spark retard or something. I would use the boost activated pump because you could have your main pump fail, it kicks on second pump, you unknowing of this go wot, and you don't have enough fuel. With it only kicking on in boost, you should notice a fuel issue out of boost before it could become an issue.

This seems to contradict itself?

Other option would be a RPM/gear select like a nitrous setup.

[sweetbmxrider]

How? I'm thinking if you run into pump issues like me and the 2ndary pump hides the fact that the main pump is having issues and you don't find out till you go wot.

[LTb1ow]

Oh ok, your saying if the first is dead and I use a fuel pressure switch it will run off the secondary. Gotcha.

Yea, thats always an issue, could wire up a light so when the secondary circuit is kicked on, I get a LED on near fuel pressure gauge.

[WildBillyT]

Originally Posted by LTb1ow

Oh ok, your saying if the first is dead and I use a fuel pressure switch it will run off the secondary. Gotcha.

Yea, thats always an issue, could wire up a light so when the secondary circuit is kicked on, I get a LED on near fuel pressure gauge.

Yup, I'd say that's a must. Being aware that a pump has failed is a great bit of info to have.

[LTb1ow]

Another option I want to look into is using a stock function in the LS1 pcm, AC or perhaps a MAP option to trigger the second fuel pump relay. Gotta talk to a tuner about that one.

[sweetbmxrider]

Could always get a nice window switch.

[LTb1ow]

Originally Posted by sweetbmxrider

Could always get a nice window switch.

Eh, turbo is not a linear load with RPM like a supercharger so IDK if that would work, IE I could be a real light load but high(er) rpm.

[S.J.SLEEPER]

hook 2nd pump up to eboost2....problem solved

[LTb1ow]

Originally Posted by S.J.SLEEPER

hook 2nd pump up to eboost2....problem solved

Not running a eboost, no C02 option

[S.J.SLEEPER]

Originally Posted by LTb1ow

Not running a eboost, no C02 option

what are you running for boost control? manual...

[LTb1ow]

maybe a boostleash2, not sure yet.