Pressuring fuel tank to prime fuel system

[Shaun387]

I read you can pressure your fuel tank with about 10-20# of air to help prime your fuel system. I did this and wasn't getting fuel at the filter......then took the inlet hose off at the mechanical fuel pump and still didn't get fuel out there either.

I took off the supply check valve near the tank, and put compressed air directly at it, maybe 40#. Took a few tries, but finally blew threw in the correct direction. I'm just making sure this isn't normal? I reinstalled the check, left the downstream hose off, pressured the tank again and couldn't get fuel out of the check valve.

 

[Mogman]

First thing I would do is remove both check valves, 40PSI is way too much pressure for your tank, I only put as much pressure as a rag wrapped around my air nozzle would allow, maybe 4-5psi.
It sounds like your tank is contaminated and the sock is plugged, if you have an access plate above the tank I would remove the sending unit and inspect the tank.

 

[Shaun387]

40 was just to get the check valve unstuck. When I removed the supply check valve, diesel was freely flowing from the tank to my catch bucket. I have a completely full tank, probably in the filler neck. So I'm guessing the tank was good, but I'll look for the access cover to remove the sending unit and look inside the tank to double check..... thanks!

 

[Shaun387]

Do you run yours with the check valves removed? I was reading mixed opinions on this.....

 

[Mogman]

Many remove the check valves including me, I have never heard of any problems with it, the same engine in the civilian world does not have check valves.
The fuel pump and the IP pump already have check valves.

 

[TNDRIVER]

I read you can pressure your fuel tank with about 10-20# of air to help prime your fuel system. I did this and wasn't getting fuel at the filter......then took the inlet hose off at the mechanical fuel pump and still didn't get fuel out there either.

I took off the supply check valve near the tank, and put compressed air directly at it, maybe 40#. Took a few tries, but finally blew threw in the correct direction. I'm just making sure this isn't normal? I reinstalled the check, left the downstream hose off, pressured the tank again and couldn't get fuel out of the check valve.

Inspect inside the tank, maybe remove and clean it if there is any foreign matter or debris , replace all the fuel lines, remove and clean the fuel filter housing and all check valves or remove them, there are several. "VACUUM" fuel to the pump, between the IP and filter. WAY too much opportunity to screw the pump up by pressurizing the tank. My two cents. And keep the fuel treated with a biocide.

 

[papakb]

When I replaced my fuel filter and water seperater I used a small vacuun pump on the fuel petcock to prime it all by drawing fuel up from the tank. The process is straight forward and simple and doesn't require anything to be disconnected.

 

[TNDRIVER]

When I replaced my fuel filter and water seperater I used a small vacuun pump on the fuel petcock to prime it all by drawing fuel up from the tank. The process is straight forward and simple and doesn't require anything to be disconnected.

View attachment 880798

OVER KILL..... I love it!

 

[osteo16]

I just hooked up a small shop vac to the fuel separator drain petcock , duct taped a small clear hose to large shop vac hose so I could not only hook it up to petcock but also see when fuel began coming out. 30 seconds and system was filled.. 5 seconds crank, fire in the hole.. And diesel doesn't combust like gas, so I wasn't too worried about my shop vac exploding. It could I guess... but doubtful.

That pump and glass jar are fancy though,,

 

[rhino1515]

If you have a Handheld Vacuum Pump/Brake Bleeder Kit, put it on the petcock, open the valve, and suck. Super simple and less prone to fire.

 

[Retiredwarhorses]

I do a fuel filter about every 2 days…never have I had to pressure the tank, hook up some gadget or what ever.
Just install a piece of 1/4in hose on the fuel filter outlet and place in a jar, crank the truck till fuel flows into the jar…hook the hose back up to the injection pump and fire it up.