Prime LJ78 fuel system (1 Viewer)

[RocketCityCrzrs]

Ok guys help the idiot. I know the primer for the fuel system on the LJ is on top of the filter housing. I put a new head on this truck so the system is completely dry.
Have cracked the injectors so they can bleed and pumped the primer on top of the filter.

The primer button only moves about a quarter of an inch. Is that correct? I have tried turning it left and right to "unlock" it but that doesn't seem to matter. Am I just dumb, help me obi wan.

The circled part of the picture is what I'm referring to as the primer.

 

[CRSWA]

That's all mine has ever done. I think the next step is to crank the starter until you get fuel from the fuel injector nuts and then tighten them down.

 

[Rigster]

Yep, that be the primer... it can take a while too if the system and filter were empty. Just keep pumping until it gets firm. I have never needed to crack fuel lines or anything else once I have positive fuel pressure in the system. I generally just start it up and let it idle and self bleed any air in the system. If this is NOT working, then there may be other issues going on like a leak in the system allowing air in.

 

[AirheadNut]

Just to clarify: pumping the primer will not force fuel out the injector lines. Once the primer starts to get hard to press the system will be bled up to the injection pump. Once that’s done the engine has to be cranked until it starts. If it continues to run poorly then you can crack injector line nuts one at a time to bleed the injector lines out.

 

[Tigris]

Correct. That is the primer. It's spring loaded and should only move about a quarter of an inch up and down, turning or "unlocking" it won't do anything, so is taking the cap off by removing the screw on top of the button.

I went through the same pain when I replaced the filter the first time. My primer was never able to prime nor change in the way it felt depressing it despite pumping it a million times.

What worked for me at the end was rigging a $6 Walmart manual fluid transfer pump inline with the output of the primer (using the supplied clear tubing and some clamps) and then I was able to draw fuel out of the tank, into the lines and through the damn primer/filter with a few pumps. I then carefully swapped the clear tubing with the output line to the injection pump and primed the bottom (which now got hard to push within a few pumps). All was gravy until I found a very small air leak in the water sensor/spigot thing at the bottom of the filter and another leak in the old filter to injection pump line. Replacing those ended the lost of prime after long park and the hard start/smoke issues I had. Now the truck starts with half a turn on the starter after 3 months parked in the garage and with zero smoke.


Best of luck!

 

[RocketCityCrzrs]

Guys, I needed to follow up with this. Thank you for the assistance. I just wasn't priming it enough, per your instructions, I pumped until it was firm and then cracked the lines. Diesel came out and then it studdered to life.

I think the engine is phucked but that's for another thread