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Hello, first thank you for taking the time to help me out. I’m going to try to remember to list everything I’ve checked/done so far.

im in Kansas, and the weather dropped down to -8 so far. Normally in the summer, my truck fires up immediately, if I tap the pedal. If I don’t it takes an extra second or two to start. In the cold like this I normally bump the key once or twice to prime the pump, before starting it up, and letting it run for a while. When it was 0°, I went to start the truck and pull it up 15 feet to jump start someone else’s car. It had just sat overnight. I fired the truck up like normal, and let it sit for a few minutes. As I pulled forward it suddenly started to struggle, I had to keep my foot basically on the floor to keep it from dying. I let off and the truck completely died. I could turn the key, and the truck would stutter to life, get to maybe 600 ish RPMs before choking out and dying again. This repeated a few times until the truck would no longer start. I cracked the the banjo bolt on top of the fuel filter, and bumped it to verify fuel was coming out with no bubbles. Just in case, I took the filter off, which is maybe 2 months old, and put some diesel 911 in about half way. I then put the filter back on, and put the rest of the 911 in the fuel tank, which is about 5/8 full. I do not believe the fuel gelled, but I figured I’d try it just to be safe. As far as I can tell the lift pump is working. I know the grid heater does not work, I pulled off the air horn, and hooked up a blow drier pointing straight down inside the intake valley and let that sit for about 10-15 minutes. If I try to turn it on while doing this, it gets very close, and it starts, but it will not catch idle. I also attempted to squirt a little bit of WD40 through the air horn to the intake valley to try to encourage it to start, and again, it would struggle but not come fully to life. I have checked the relay inside the fuse box under the dash andput in a new relay for the fuel system just in case. There are no leaks under the truck, no fuel or oil. I can’t get the truck to run long enough to crack injector lines to see if fuel is actively coming from there, and I do not have the tools to test the compression in the lines. Im kinda stumped and don’t know what to try next, and this is my only way to work. Any information or help would be appreciated. Thank you for your time.
 

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A signature would help so we know what’s done to your truck. From the sounds of it you think your truck has a factory electric lift pump and it doesn’t. A non functioning grid heater isn’t helping your situation out any. It also sounds like your idle is set too low if you have to bump the throttle to start it under normal conditions.

Have you checked the function of the fuel shut off solenoid? Maybe it’s not opening the whole way and with the cold it isn’t getting the amount of fuel needed to stay running.
 

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Discussion Starter #4
Yes the FSS works, and yes I did bleed the lines afterwards. I’ll be sure to update the signature but essentially it’s a stock 96 2500 5.9 12v, with an NV4500.
 

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Your truck doesn't have a in tank fuel pump, just the mechanical one on the engine. When you bled the system after the filter being off it wasn't gelled or you wouldn't have gotten fuel out.
 

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I'm the least knowledgeable here, butI have had my 96 12 valve for 22 years now. I agree with Nuljas23 about the fuel shutoff valve. This definitely will shut the fuel off. Check your POS battery post for two smallish black wires attached to post bolt. Any corrosive resistance can cause insufficient amperage to the solenoid. I had to replace the solenoid once in its life.
 

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PS There is no substitute for that block heater in frigid weather. The cord is easily replaceable, are you positive the heater grid itself is bad?
 

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Following! I have a 96 2500 12 valve that has been struggling with almost these exact symptoms. I also noticed reduced power since this problem began. My grid heater and block heater both work, but the truck still suffers the same symptoms. The first time it happened the truck was idling after running and pulling for awhile, but then did exactly as OP described. My mechanic thinks its backdraining but I think it's something else since we've tried replacing fuel lines etc. Also doesn't seem exactly right since it can happen while running, and I wouldn't think it would get air in the system from a small leak while running.
It has a relatively new lift pump (last year I think). We replaced the solenoid for the fuel shut off in 2019. Gonna try replacing the OFV on the p7100 next to see if that stems the suspected back draining. I'll report back if we find a solution. Hoping someone here has dealt with this successfully!
 

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Just pinch the return line from the IP and if the truck starts right up then the OFV is bad, make sure to unpinch as soon as it starts.
 
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I fired the truck up like normal, and let it sit for a few minutes. As I pulled forward it suddenly started to struggle, I had to keep my foot basically on the floor to keep it from dying. I let off and the truck completely died. I could turn the key, and the truck would stutter to life, get to maybe 600 ish RPMs before choking out and dying again. This repeated a few times until the truck would no longer start.
OP: By any chance were you on an incline of any sort? The two times I remember most vividly (cuz I couldn't get started again), my truck was facing uphill. The first time it was idling after pulling for at least 25 min (warm), the second time it was idling while warming up on a cool Sept morning (maybe below freezing?) without having been plugged in. In both cases it idled for at least a few minutes before dying. From there could get it to chug a bit with foot on the floor, but eventually no start at all. Maybe the hill is just a coincidence... Curious to know what your truck's attitude was when it died.
Just pinch the return line from the IP and if the truck starts right up then the OFV is bad, make sure to unpinch as soon as it starts.
Thanks. We'll give that a shot. Would a bad OFV contribute to symptoms described here?
 

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Yes, Add a pressure gage even if temporary under the hood. If the FSS is intermittent it could throw a wrench in your logic so next time you start it - tywrap the FSS up so you rule that out entirely (yes you will need the cut the tywrap to shut it off). WITHOUT a gage - you could check for air by cracking the filter bleeder and/or by depressing the primer button on the lift pump. You will feel resistance when depressing it. If you have a gage you can see the pressure and rule out the OFV at the same time. If it takes multiple depressions on the manual primer button - you have AIR and the motor needs to turn over the same amount of times to build pressure AKA hard start. I just went thru this with mine and the best advice I got was "If your diesel has hard starts/not running there are THREE things to focus on - Fuel, Fuel and Fuel." The question is WHAT is mucking up your fuel supply - there's the trick. First thing - FSS, OFV, then AIR. IMHO. YMMV
 
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