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................... if you own a 7.3L
 

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Discussion Starter · #22 ·
Update: I syphoned out 25 gallons of the mixed fuel, then I drilled a 3/8" hole in the rear of the plastic fuel tank to let the remaining fuel (about 8 gallons) drain. Then, I blew compressed air into the tank fill tube to force out the remaining fuel out of the drilled hole. Then I went to Harbor Freight and purchased a plastic welder (soldering iron) for $15. It comes with black plastic sticks for filler. I used the iron and melted the plastic around the drill hole and added some of the black material they provided. It took about 10 minutes and the hole was plugged very nicely. The next day I filled the tank with 10 gallons of Diesel and it held - no leaks so far.

Lastly, I replaced both fuel filters and added Seafoam directly to the primary fuel filter reservoir. Primed the fuel lines a few times and turned it over. The first few times it ran rough for a sec and died. By the 4th time it started up and ran great.

I drove it to the store and it was running strong. Fingers crossed but I may have dodged a bullet.

Thanks for all the tips and well wishes. Take care guys.
 

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The knee-bone is connected to the ear-bone...

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Ok, but the picture shows a common rail design, with high fuel pressure going to all cylinders at once, I thought they were HEUI unit injection? Where engine oil is pressured to 23,000 psi, and each injector uses that pressure to fire low pressure fuel into a cylinder at high pressure. Maybe the schematic is not showing all of that.

What PSI is the diesel fuel at on the red circuit compared to the blue circuit.
 

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Do you want to talk about the 6.0L (his pics are of the 7.3L according the his labeling)?

To start with, neither the 7.3L nor the 6.0L have high pressure fuel rails. They have high pressure oil rails. The (extremely high) fuel pressure inside developed in each injector. Up to 28,000 psi with the 6.0L (each injector has a 7:1 intensifier piston operated by oil pressure that ranges from 600 psi at hot idle, up to around 4000 psi at WOT).

With the 6.0L, the pump in the HFCM will develop a pressure of around 75 psig and then the regulator on the side of the secondary fuel filter will hold it around 60 psig (varies with engine operation, 50-70 psi).

According to Ford literature, for injector longevity, you don't want to see below 45 psig with the 6.0L. Personally I take action at 50 psi. Fortunately my injectors are still original at 236k miles.
 

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Can't believe I'm typing this because I've never even come to making this mistake. I stopped to fill up on the way home. Had to do a 8 point turn just to fit into the spot next to the diesel. Dude in front was chatting with me as I went to pump the gas. We own all gas vehicles and I just wasn't paying attention and grabbed the 87 and filled it up. I had about 10 gallons of Diesel and added 20 gallons of gas. Didn't catch it at the time and drove it home (3.5 miles). It started sputtering a little when I was pulling into my driveway. Parked it and shut it down.

Thankfully, this isn't a regular use vehicle but I need to resolve the issue. Hope I haven't already caused major injector and lift pump damage.

I've done tons of work on the engine myself so I think I can drop the tank and start to try and resolve this.

Any tips/thoughts would be much appreciated.
My old farm tractors wouldn't give a crap, but these new fangled truck injection systems sure as Hell do. I would definitely drain as much of the 2/3 gas mixture out and fill with fresh diesel and add two doses of lubricity additive. Replace the fuel filters too. A little gas is tolerable, but 2/3 of a tank ain't gonna cut it.
In the olden days, I read that one could take a gallon of low octane leaded gas (MOGAS) and add a quart of 30 weight oil to it to make emergency fuel for indirect injection diesel engines. In college, I watched a farm tractor connected to a generator with a Frankenstein fuel supply system that could switch between nearly any oil known to man. The only differences were the exhaust smell and the power output I wouldn't recommend anything other than low-sulfer highway diesel for any diesel engine unless it's agricultural equipment. Even the new farm tractors are requiring low-sulfer diesel.

Good luck to you.
 

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Discussion Starter · #27 ·
Thank you. I got it all squared away. So far so good. Hell, the regular unleaded may have cleaned out my injectors 😉

I wouldn't recommend trying it intentionally but luckily it only ran with the mixed gas for about 4 minutes.
 
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