bigblue70

I picked up A 90 cummins for A motor swap, thing runs great but I went to change out the fuel pin and the hole was full of clean oil. I've had an issue with fuel getting in there on my truck but don't see how oil can get in. Especially clean oil. Any ideas?

Onemoparnut

Maybe someone put clean oil in there to lubricate the pin that is all I can think of.

bannerd

Same here, I don't see how oil would get in there. Sounds like a smart idea though.

93-12Smoke

Wouldn't that slow the reaction of the fuel pin if it was full like the OP stated

bannerd

I don't think it would, the pin is under tension. As the pin rides the ramp the spring tension opens it up. I see the idea of lubricating the ramp so the needle doesn't get worn out. I usually put a small amount of grease on the ramp for lubrication. Motor oil isn't a bad idea.

93-12Smoke

I'm saying the fuel pin is pushed up and down with boost pressure. If the area under the diaphragm is full of oil it will not compress and push the pin down

Jim Lane

Couldn't get it completly full though, the cavity under the diaphragm is vented to the atmosphere, remember the rubber boot above fuel screw, thats why it leaks fuel.

93-12Smoke

Good point