no start, fuel filter + cold weather problems

[dieseldirt]

first of all, this is on a '89 f-250 with a 7.3 idi. also, it is cold here. single digits/below zero...
i was taking the truck for a short spin after fixing something completely unrelated. i started it, idled for like 10 minutes, drove for like 10 minutes, then...
the "fuel filter restriction" dummy light came on, and about 5 minutes later, just as i got it parked, it stalled and wouldn't start again.

i have dieselkleen (white bottle for winter) in the fuel. i have been meaning to change the fuel filters for awhile but i'm pretty sure this sudden stall is related to an unusually cold weather spell.

this morning i plugged the block heater in for 2 or 3 hours and then tried to start again. noticed that with the ignition on, there is a buzzing/humming noise which seems to be coming from driver side frame rail right by the front edge of front fuel tank. the truck has dual fuel tanks, and this noise changes pitch when i flip the tank selector switch (this is all with the engine off but the ignition in start). I was wondering if the noise I described could be the fuel selector switch valve? Or if it's just related to the filter being iced/clogged or something? Should I change the filter then see if the buzz goes away? The noise is not the fan/blower or the block heater. With the ignition on, i can hear blower (on low), glow plugs cycle as usual, dinging, all normal PLUS this louder buzz/hum coming from frame where i described.

I am also stumped as to how there could have been a cold weather related fuel problem like wax/ice/gelling because i have dieselkleen in the fuel. especially after running for 15-20 minutes "just fine". One thing i thought of was checking if the fuel filter heater in the filter header is working. My truck does have one, right? I can't check for heat because the truck won't start. In this picture, which of the 2 electrical connections is the fuel heater? (PICTURE 1) Also, i found a smaller electrical connector (looks like its for a sensor or something) that is just dangling. I think it's the water-in-fuel light connection but i could be wrong. (PICTURE 2)

Finally, is it stupid to just change the final filter (under the hood), not the frame mounted one as well? Also, does the "fuel filter" light pop on for just the final filter, or for either one, or for any fuel supply problem?

Thanks for reading! maybe i just need to change the filter, or get some of that diesel 911 stuff into the fuel system or something, but i thought i'd get the right info before doing anything.

 

[Agnem]

The block heater won't help if your fuel is gelling. Is the buzzing a frame mounted electric fuel pump by chance? I'd assume you'd know you have one, but dumb questions still have to be asked.

 

[suv7734]

Hard to say for sure about the buzzing but the fuel selector does have a small motor in it that does the switching. Do you have an electric fuel pump installed because that area is a common place to mount one. How full are the fuel tanks?
The driving for 10 or so minutes can sometimes make a difference as far as fuel gelling goes since there is no wind when the truck is sitting still (just a thought).
The connectors you are asking about are as follows: The oval shaped one on top of the head is the heater, the other one at the outlet side of the head is the filter restriction sensor and the loose one is the water in fuel sensor which connects on the bottom of the filter.
If your fuel system is stock the only filter is the one in your pics so if there is one on the frame it is not a factory piece.

 

[dieseldirt]

nope i don't have an electric fuel pump. i have the stock mechanical one under the hood. after doing more research, i am pretty sure the buzzing is the Fuel Selector Valve. and i'm pretty sure that it froze up because i didnt have very much fuel in the tanks. is there any way to "defrost" the FSV and fuel lines affected by the problem other than just hoping it warms up outside? a hair dryer and extension cord?

i took off the old filter and it wasn't iced up inside or anything but i went ahead and put a new filter on because it really needed it. now due to the "frozen" FSV or whatever it is, i don't think i'm getting fuel through. i realized this while trying to bleed the air out after installing the new filter. i tried cracking a injector while someone was cranking but just as i got it loose they finally killed the batteries.. too much cranking! i guess i should use that schrader fuel priming valve on the filter header and see if i can get fuel there??? after charging the batteries..

my fuel system is stock so that would mean the filter in the picture is my only fuel filter. i just heard people talking about "changing their frame mounted filter" and what a pain it was... i wonder what trucks they were talking about. i also have read about my fuel system and i keep seeing the fuel filter referred to as the "final fuel filter".. are there screens/filters elsewhere that can be cleaned or changed? that was my question i guess.

 

[smoking89IDI]

What they mean by the "final filter" part is that you have filter "socks" on the ends of your pickup tubes in the tanks that they also consider "filters" although I have just found they usually fall off over time and only let you use part of a tank of fuel (don't ask how I know).