98Redbird

I recently replaced the injectors on my 01 cherokee 4.0. Before I started it up again, I cycled the key from the on/off positions 3 times before cranking, to prime the system. A buddy who was there with me said that it does no good because it's a returnless fuel system, and that the regulator is at the tank/pump. Only way to prime, and get the air out would be to pop open the pressure relief on the rail while "priming" Which seems like a good point, wouldn't it just deadhead with the air in the system? So, what good does "priming" keying on and off do in that case?

Jeep started and ran fine btw, I'm asking more or less to better understand the system.

Thanks

jpmarine6786

Just start the engine. I did and it fired up within 10 seconds. I would think the air would just go through the injectors into the cylinder, so you wouldn't need to get the air out of the system.

cruiser54

It still needed the prime. Not a huge deal. You coulda done it either way.

Fred/N0AZZ

Same here I just turned the key on to start the pump for 10 seconds then cranked to start.