johnny5.9

Hi guys. I'll try to be brief yet informative enough. So the 02 truck ran good all summer. Though fuel pressure always fluctuated more than what other guys reported. But it was healthy enough. As weather got colder, I noticed the pressure drop quite a bit more if I got on it a bit. To the point it was going below 5 for a second then I'd get off the fuel to shift and it would bump back up. Yesterday morning I went to start it and it would be at about 11 psi during heat grid cycle then drop like a rock to zero once started. So I'd shut it off. Talked to FASS and the very helpful guy recommended the hard start fix since it seemed the ECM wasn't sending enough power kick over the solenoid to send power to FASS. I did that and it worked good yesterday. Pump did it's 25 second prerun louder and longer than it ever had, making me think I had an ongoing problem with low voltage, explaining the pressure drop on high load. Ran fine all night. Now today, same thing. Except the pump is super quiet and sounds tired on the pre-run. It builds to about 18 psi on the attitude and then when started, drops like a rock back to 0. Messing with it today, I found whoever installed the FASS had the wire from the solenoid to the FASS and the constant 12V hot switched. So I corrected that at the solenoid. Hooked up a volt meter to the 12V going from solenoid back to FASS to check voltage and and turned the key to run. I could hear the solenoid click over and it held a steady 9 volts to the pump. Is this not enough voltage? I suspect maybe my fuel gelled? It seems the pump labours to build enough line pressure and then when the engines fires, the VP44 draws the fuel faster than the poor FASS can send it resulting in zero fuel pressure. Does this make sense? I got a full tank of fuel a bit ago from a station I only occasionally go to and the pressure dropping way low during loads started after that. Any help would be very appreciated. I've never had gelled fuel before ever. Do I need to purge the whole line back to tank? Is the fuel in the tank trash now? Can it be "ungelled"? Thanks for reading. I appreciate it.

PS: I do have a little inline fuel filter before the FASS. So I should take this off and check as this would be the first place to collect the gelled fuel right? Of course I'm stranded right now with no other vehicle here to do anything until my gf gets home. Ugh.

oliver foster

Add a good strong shot of Diesel 911 to the tank. Then pull that inline pre filter off and replace it with a fresh one or no filter and see if you can get it to start up.
Getting the truck into a warmer place always helps as well.
The fuel in the tank will be fine to use once you get some anti gel in it.
The filters might need to be changed to get it working again now though.
Add some diesel 911 right into the FASS filter if you pull that off as well.

Check for water in the filter as well.

johnny5.9

Thanks for the help.

johnny5.9

Does anyone happen to know if 9 volts is enough going to the FASS?

johnny5.9

So FWIW the problem seems to be solved. I write this follow up in case anyone else is having similar issues. I think it was a collection of contributing factors that lead to the failure. I switched the inline filter before the hpfp and played around with some wiring, checking all my connections. I jumped the pump with 12V straight from the battery, grounded to the frame to verify the pump worked. After that bit of a "jump start" it built pressure on the pre-run and then held a steady 16 idling. I doubt it was a gelling issue, the fuel that came out of the pre-filter was not cloudy, but perhaps the prefilter was clogged, that combined with wiring errors by the PO causing lower voltage to the hpfp reducing it's power, and the new colder weather thickening the fuel led to the low pressure I suspect. I had about 9V at the pump, which it wasn't happy with given the conditions, but now I have about 12.5.