I have a '78 long bed. For some reason fuel will not flow from the gas tank. (There is plenty of fuel - at least four gallons of gas in there.) It has an electric fuel pump, aftermarket, mounted in the engine compartment which has worked fine for years. It will pump a cup of gas in about five seconds.
I suspected a clogged in-tank filter, so I blew compressed air into the fuel line toward the tank to clear it out, and found no impedance. The old fuel pump is still in the tank.
Has anyone else had this situation? If so, what did you find fixed the problem?

As a side note, the CHG light is on constantly - even though the charging system is fine and the fuses are all good. Another mystery to track down.

Thanks in advance for your suggestions!

 

fuel system experience

I had a similar issue with my fuel delivery system. First, I would check that there is certainly no blockage in the original fuel pump in the tank. I personally wouldn't hook up an aftermarket pump down stream from the one in the tank because you have introduced to many variables. Do you have a PSI gage aft of the aftermarket pump? if so, are you getting pressure and can it keep up with the demand? Second, if you stick with the aftermarket pump I would pull the tank anyways and remove the fuel sending unit (on mine the fuel sending unit has the pump on it, its one unit) and there is a check/Pressure relief valve just up-stream from the stock pump. Mine was clogged with 30+ years of sediment and "stuff". I pulled that tank 100 times it seemed before I figured it out. I was messing around with this valve with a scribe and out came this clump of sediment. At this point, if you so choose, I would just pup a new fuel pump in the tank, remove the aftermarket one, install a direct reading gage after the fuel filter and be done with it. If you put it back stock, make sure there is a screan assembly in the tank to pre-filter the fuel before the pump, otherwise you will have a similar issue!!!! Trust me, that was one of the 100 times I dropped the tank!!!

Hope this helps!!!!!

 

i would do what NavyMC says but if you still think about rust sediment ,try Electrolysis rust removal
Electrolysis rust removal - motorbike fuel tank

this i what i've been trying to do on my days off but there something always coming up and never do

 

remove your old fuel pump and install a new one in the fuel tank and get rid of the aftermarket one and install a neww filter