Engine/Transmission (1998.5 - 2002) Installing a liftpump switch.

[rashwor]

I am going to install a toggle switch on the hot wire going to the lift pump. The purpose of this is to get fire to the pump when I change my fuel filter so that I can use the lift pump to fill the canister and remove as much air as possible before cranking her up.



Before you tell me I don't need to do this and how I can bump the ignition to do what I need to do, I had a TSB applied to my ECM for hard starts. With this TSB the lift pump buzzs for only one to two seconds when the key is first turned on and does NOT run at all with a simple starter bump. Changing the fuel filter is a bear!



My questions are: What amp fuse should I put on the jump wire that will go to the lift pump from the toggle switch? How may amps does the lift pump pull? Which wire into the liftpump from the factory wiring harness is the hot wire?



TIA

 

[Gary - K7GLD]

HMMmmm - I've not seen the schematic on the primary wiring from the computer to the lift pump, so can only suggest caution in applying power to the LP by bypassing the computer - possibility that voltage feeding back the "wrong way" into the computer or LP control circuit MIGHT cause damage?

 

[gooded]

Rashwor,





I've always had problems with that bump the starter stuff. What I do is take the pressure test port plugs out of the top of the filter canister and use a funnel and some clear tubing into the INLET pressure test port and add diesel until is just starts to run out of the outlet pressure test port. I put the plugs back in and it never misses a lick. Don't run a hot wire to the pump you are sure to damage the PCM and that's big bucks.



Darryl

 

[gregdoerfler]

i would think if you wanted to you could get a double pole double throw switch and find the positive and negative wires feeding the pump, cut them and hook those to one side of the switch, then the other wires from the pump itself hook to the center, then take hot and negative from the battery and hook to the other side using a fuse .

 

[NScott]

Why are you going to this trouble at all???

The lift pump operates for about 3 to 4 seconds after the key is turned to the "on" position. You can cycle the key from "off" to "on" without bumping the starter in the "start" position.

I have used this method several times to rid the system on trapped air and to fill the filter canister with fresh fuel.

My . 02 worth.