So I’ve read tons of info on this….. but still stumped.
84 6.9
Replaced the mec fuel pump
injectors
all the lines
cleaned out the electric pre pump
all selinoids in ip are working.
put fresh gas to top fill up more than 1/4
tried atf in filter (replaced that as well)
starts at full ballz blows a lil black then white then dies…… did put the IP cover back on wrong and it went runaway as expected. Put can’t get it to stay running more than 5-15sec.
put a inline guage and holds pressure for a few days. WTF
any thoughts?

 

You could always double check your fuel supply by running the fuel filter directly from an auxiliary fuel can.

 

Two fuel pumps and gas. There's your problems.

Have you tried bypassing the tanks, fuel lines and selector valve by unhooking the return line and feed line to pump into a 5 gallon jug of diesel yet? If not start there. That will let you know if the engine and IP are good enough to run. If it runs fine then, then you know you've got to track down fuel lines, tank pickups, selector valve etc.

If it still doesn't run, how old is the IP? How many miles on it? How long as the truck been sitting without running?

 

If the injection pump is very old and you installed new injectors then that could be the problem. A tired pump will not create the pressure needed to pop the new injectors. And it sounds like the only thing you haven't replaced is. . .the injection pump.

 

Gas!?!?!? Diesel fuel only.

 

Big blue2 it’s diesel. Not that dumb. Bought this to learn diesel motors and Deff gettin the lesson. As far as running off a separate tank was thinking the same thing. I have changed all thr rubber down to just before the selector switch. Give that a shot next.
No clue how old the IP is but it’s Deff moving fuel.

 

When the engine went runaway did it run longer than 5-15 seconds?

 

No offense intended. I just wanted to make sure. It wouldn't be the first time that gas was put in a diesel rig.

Call it fuel or diesel or diesel fuel. Never call it gas.

 

yup went for a min or 2 till I killed the air. Was all white smoke and high idle.

 

and stupid side note. Tried a towel to kill the air. Restricted it enough to run somewhat normal. That was pre all the rubber fuel pump and injector change. Up 2 the tank switch anyway. Running it down. 🤞

 

all good man. It’s the stuff that makes it go boom. Gas cars have been the jam for years. Trying to expand




doing that 79 now. Finished that 83 and the last ones a 302 SC swap in a Volvo. 😂🍻

 

Once I was traveling and camping the back country in Oregon. There is a network of logging roads that cover half the state. It's very easy to find yourself lost out there. I was running low on fuel and I emerged from the bush to a remote country store that had diesel and gas. In those days the central planners in Oregon decided that only a trained employee was allowed to operate the pumps. So I pulled in and a young woman came out. I said 5 dollars of diesel. Just enough to get me to civilization where fuel prices would be more reasonable. Well she started fueling my truck but accidentally put in a gallon of gas before realizing her error. I asked her to get it out of my tank. But we had no way of doing that. And since she was pretty shaken by her error I asked her to fill the rest of the tank with expensive diesel. It was about twice the town price. She said she couldn't do that. Then I had her put 5 gallons in my rear tank. I used that tank to get to cheap diesel. I filled the front tank to the cap with a gallon of gas in there too. Topped off the rear tank too. Then I ran mostly on the rear tank, occasionally switching to the front tank for a mile then back to the rear tank for 10 miles. Then every hundred miles or so I topped off the contaminated tank with another gallon or two. Kept doing that for the next 1000 miles. After 5 or 6 top offs I figured I had it diluted enough to run on the front tank for 40 miles and then topped off like that several more times. Eventually I ran the tank out and could go back to normal. Today you can self serve diesel in Oregon but gas must be filled by the attendant. Oh thank you so much my government minders.

 

1 gallon of gas in 17 or 18 gallons of diesel will do no damage in our old girls.
if i had trucks with summer fuel in them, i would add a gallon or two and them top off the tanks to thin the mix a bit to prevent gelling in the cold.
back in the 70's and 80's i used to put in 1 gallon of gas for every 10 gallons of fuel in the fuel tanks of the detroit and mercedes powered trucks to keep them running in winter.

 

Ok so ran a can of fresh directly to the mechanical pump. Bypassed the oem electric pre pump. Same ****…… states for a Cpl sec. White smoke. Then dies. Shoots a lil black at first tho. If I disconnect the top return selinoid I get a Cpl extra seconds of run but still white smoke like crazy. Dosent smell like coolant/sweet. wtf. I’m things at this point it gotta be the IP that’s the only thing I haven’t replaced. Was thinking about “turning it up” any thoughts here?

 

dumb this it’s doing the same thing as before the injectors, returns, mec fuel pump and oem electric where cleaned and/or replaced.