7.3 idi starts...runs then dies

[IDI_Journeyman]

Hello Oil Burners, I have a 1985 Ford F-250 with a 7.3 idi Ats turbo. She's 4x4 with a ZF5 also. I recently bought the truck from an older guy in Sacramento, he said his dad bought the truck (blown 6.9 4 speed) and it came with a Crate long block 7.3 idi with a 5 speed. They payed an Arab mechanic to put it in and it took him a year!

anyways the engine has around 12,000 miles on it and has a lot of newer parts. It's just been sitting in the guys back yard for a few years. Dude didn't drive it more than a few times every year. The truck runs really good but a few days ago I saw that my #6 injector was leaking fuel and filled up the pocket my glowplug sits in. The truck came with some O-rings for the injectors so I replaced the two (leaking O-ring was loose) I purged the system and she fired up after battling for a few minutes. Next morning she stared right up, ran for 3-4 seconds then dies. I purged it again and she started up fine. It Drove fine on the highway then I went to a buddies house for 3 hours, I came outside and it did the same thing again. started, ran for 3 seconds then died. It has a shiny new lift pump and the IP doesn't look too old. It might be the IP out of the 6.9. I'm buying some new injectors and return lines from typ4 but aside from that what would be the issue? I know these engines fairly well but I'm still learning. I think air is getting in my fuel system somehow. Any help would be appreciated thank you.

 

[sjwelds]

You're on the right track with air intrusion. My guess is once you get new return lines on it'll fix the problem.

 

[79jasper]

Likely just return cap orings.
But be a good time to replace the other fuel line olives.


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[IDI_Journeyman]

Ok, many thanks to the both of you. I'll order the lines and report back when they're installed

 

[icanfixall]

Welcome to the forum. My guess is you have a leak so air gets into the fuel system and the fuel drains back to the tank. My guess is the feed line olives from the filter outlet to the injection pump are hard and dried out. They are inside the brass line nuts. Try tightening the nuts and see if that is the fix. You have another olive on the inlet line to the filter too. If you choose to replace these olives you need 2 of the 5/16 size for the outlet line and one for the inlet line size 3/8. these olives appear to be a cut of plain rubber hose. Some have actually made them this way. Any good injection pump repair shop will have them.