I've been following the posts helping Hawaiin Builder with his problems, and it has me wondering what/how is the stock lift pump controlled. When I was converting my truck to WVO I bought a Holley Blue to pump the grease and supplement the stock lift pump. I figured that I would splice into the wires to the factory pump with a relay to run the holley. Using my test light clipped to a ground I was checking to see which of the two wires was the positive, and it wouldn't light on either with the truck running, I checked the fuse and it was okay. In my haste to get up and running I just took a fused line off the dist. box under the hood and control the holley with a switch. Can anyone shed some light as to when my stock pump should be on, and what is this modification that is done to turn it on with the ignition switch. Why do you do the modification, easier starts?? Thanks.

2 circuits operate lift pump on your '95 OBDI truck, starter circuit and Oil Pressure Switch. So your lift pump should run during cranking and as long as you have Oil Pressure. The OPS is known to burn out the internal contacts from the electrical load which is most likely why yours is not running. Best is wire a hot wire from the Dist. that is hot with key-on to the relay that runs your lift pump, or just like you did your holley pump with a toggle switch.

The other way to relay it is to splice in on the OPS connector after replacing the OPS. The orange wire is always hot (common) so you cut the grey in two, put the end from the connector to the relay coil and the other end going to the liftpump off the switched circuit off the relay. This will allow the common to pull the lift when there's oil pressure and will shut off fuel when the engine dies. Edited by: quantum mechanic

A diagram is posted on my site http://mysite.verizon.net/vze54tx9/ (http://mysite.verizon.net/vze54tx9/)