Reminder for those with an electric lift pump

GOT-Torque

GOT-Torque

is
Joined
Jul 2, 2007
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Just thought I would post up a note for those that may have done the same thing as me. I run a FASS fuel system on the truck and no longer used the factory wiring to power it as the stock fuel pump wiring is known to lose it's voltage supply when spinning higher rpms 4500+. In any case, I powered it up off a supply that is powered anytime the key is turned on.

I just recently figured out that this power source is hot anytime the key is on, except when you are cranking the engine. :bang

It sure makes it a pain when you are trying to bleed air out of your lines cranking on it, and the lift pump isn't running...

So now it is wired directly to the battery thru a switch in the cab.

Hope this helps someone out...
 
Find the trigger wire for the fuel heater relay. Thats what I run my lift pump (and shut off solenoid pull circuit) off of. Hot in both Start and Run positions, but off in the Acc. position. Can tap it right out of the PDC main harness.
 
i never thought of that, im gonna run a switch to my battery now too. good idea
 
Jesse any chance you could draw up a quick wiring diagram of how its wired. I want to do this as well and it put it on a switch. Also a good safety measurement incase a plunger ever stuck in the pump you could just kill the power to the pump via the switch.
 
yoshi470 said:
Jesse any chance you could draw up a quick wiring diagram of how its wired. I want to do this as well and it put it on a switch. Also a good safety measurement incase a plunger ever stuck in the pump you could just kill the power to the pump via the switch.
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I never thought of that. Good thinking!
 
Find the devices that don't shut down during cranking, wire the relay to that. I have mine setup so I kill the fuel shut off, air shut off, and fuel pump from either the key or the rear of the truck. I have a switch in the truck that bypasses the air shutoff, so it doesn't activate when you just shut the key off. Basically the toggle switch on enables the air kill.
 
I have a 3 way dump valve to install on the fuel line. I plan to hook it up to the same lever as the air shutoff.

The key in the truck doesn't do much anymore, LOL.
 
yoshi470 said:
Also a good safety measurement incase a plunger ever stuck in the pump you could just kill the power to the pump via the switch.
Click to expand...

The kill-switch isn't a bad idea, but the dump valve would be the best choice. Even after you kill the FASS or AD with the switch, the pump will continue to run for a short period of time until the line is empty of fuel. Not nearly as big of a deal on a truck with an auto gov pump, but the less time it is running when the plunger sticks, the better off you are. $.02
 
j-rod said:
The kill-switch isn't a bad idea, but the dump valve would be the best choice. Even after you kill the FASS or AD with the switch, the pump will continue to run for a short period of time until the line is empty of fuel. Not nearly as big of a deal on a truck with an auto gov pump, but the less time it is running when the plunger sticks, the better off you are. $.02
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Air shutoff is your best setup.

I used a 3 way dump that is tied in to the emergency brake cable.
 
j-rod said:
The kill-switch isn't a bad idea, but the dump valve would be the best choice. Even after you kill the FASS or AD with the switch, the pump will continue to run for a short period of time until the line is empty of fuel. Not nearly as big of a deal on a truck with an auto gov pump, but the less time it is running when the plunger sticks, the better off you are. $.02
Click to expand...

I wouldnt think it would run for more than a few seconds but i've never been in that situation and hopefully never will be just thinking out loud here. I would like to rig up a 3 way dump valve and get a air shut off eventually.
 
I used the stock circuit for normal driving but tapped a hot wire in coming from a toggle switch. I just flip on the switch when I pull or think I will go over 4k.
 
run power direct to the battery and run ground through the switch. I've always been told to do it that way b/c it puts less load on the switch and reduces the chance of burning everything up b/c of a ground out. It will also make the switch last much longer. I used to do plows and liftgates like that and never once had a problem even running 24v through them.
 
1lowdiesel said:
run power direct to the battery and run ground through the switch. I've always been told to do it that way b/c it puts less load on the switch and reduces the chance of burning everything up b/c of a ground out. It will also make the switch last much longer. I used to do plows and liftgates like that and never once had a problem even running 24v through them.
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Bad thing about using the ground is if your wires get grounded it keep the item on. If the 12V grounds out it will pop a fuse. I can't see using the ground or the positive changing the life of a switch.
 
1lowdiesel said:
run power direct to the battery and run ground through the switch. I've always been told to do it that way b/c it puts less load on the switch and reduces the chance of burning everything up b/c of a ground out. It will also make the switch last much longer. I used to do plows and liftgates like that and never once had a problem even running 24v through them.
Click to expand...

I was taught the same thing, i think that the switch lasts longer because it wont be arcing inside of the swith near as bad when you are switching the ground and not the hot wire
 
joeturbo said:
I was taught the same thing, i think that the switch lasts longer because it wont be arcing inside of the swith near as bad when you are switching the ground and not the hot wire
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The inductive load is what is drawing the arc from the current trying to change instantaneously. Trying to change the current across an inductor(coil is an inductor) will develop a voltage across the switch proportional to L di/dt IIRC.
 
I Agree with zstroken on switching grounds. I keep it simple. 30amp toggle switch with power from the battery, 10gauge wire and be done with it.
 
Yea shutting the power off for the lift pump will take forever to run the injection pump dry. I have a cable shut down and my airdog powered with a switched ignition power wire. I can shut my ignition off and let the truck idle for i dont know how long. I let it go for 30 seconds just to see and it didnt even start to run rough.
 
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