Hello, I have a 91 F-super duty with the 7.3 idi diesel. I got the truck for free since it had been sitting in a field since 2009. It has almost 400,000 miles on it, it was a service truck. I’m having trouble getting it running. I gave it a brand new starter, new fuel filter, fresh fuel, oil, and batteries. It started, ran okay. But I was replacing the plastic fuel return deals on the top of the injector due to it cracking. In the process I managed to cross thread the tops of two injectors while trying to put the hard lines back on.So I bought new injectors, installed them, hooked everything back up and it just won’t stay running. It’ll run for a little bit then just die out like it’s not getting fuel.i took a line and ran it straight from the fuel pump to a diesel can. Same story, crank it, start for a little bit then die out and won’t start back up afterwards. Two injectors seem to have a little fuel leak but nothing bad enough to where I’d think it wouldn’t start. After cranking there’s air in the Schrader valve but while I’m cranking it is pushing fuel out. I’m stumped, I really don’t want to replace the hard lines but maybe the next step? Thought I would post here to maybe get a second opinion. Thank you

 

Hopefully you didn't damaged the hard fuel lines between the Injection Pump and injectors. Before replacing them do this:

• Run the fuel filter assembly to a fuel can of diesel.
• Have a buddy crank the engine while you bleed the schraeder valve on the fuel filter. A solid stream of fuel should come out.
• Bleed each of the injectors while a buddy cranks the engine. I like to bleed them by the firing order 1, 2, 7, 3, 4, 5, 6, 8. My truck usually coughs by #7 and will start when bleeding #3.

Make sure you wear safety glasses while bleeding the injectors. They will spit fuel when you loosen the hard fuel line.

Also, give the starter time to rest between bleeding injectors. I'll only bleed each injector for 5-8 seconds and then give the starter 45+ seconds to rest.

Report back once you give this a try. Good luck.

 

When it starts easy or fairly easy, and runs for a few seconds but stalls, followed by a hard or no start, that means it's running on the fuel that's still in the injection pump, but the fuel has drained back from the system and can't prime in time on the small amount of fuel in the IP, so it stalls. So all the cranking, is trying to re-prime the system.
The most common place is the o-rings in the return line caps, but there are rubber seals in the steel hard supply lines too that can cause this too. With a truck sitting for so long, you should suspect and replace the fuel pump, preferably with a duralift electric pump w/ a block off plate for the lift pump; a big block chevy plate fits just right.

There is also a return line on the back of the return line system on the drivers side. Make sure that is replaced temporarily with a hose, returning back to your jug also, so that you know it's not plugged.

That's a heck of nice truck rig to find for free!

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The F-Super Duty 1987-97 (the original super duty prior to '99 pickups) was Fords introduction of the class 4 medium duty truck. It is a commercial cab & chassis 2WD dually only optioned truck. Though a few conversion co's such as (but not limited to) Quigley, did convert some to 4WD. They came with 460 gas engines all through the production run, with the optional 7.3l IDI diesel engine from introduction through '94, then the optional 7.3l DI (power stroke) diesel from '94.5 - '97.
HD transmission options include both the manual ZF5 and the E4OD automatic.
Cab configurations were standard regular cab only.Though you may come across other options (super cab & crew cab) they were custom built.
Trim options were that of the pickups (XL, XLT).
Known at the time as the "One Ton Plus." It sports a HD frame and the mighty hydroboost brake system with four wheel disc brakes. The beefy sized calipers make stopping the heaviest of loads a very safe and secure truck to work. Although they are 2WD trucks, they are equipped with 4WD transmissions but rather than a transfer case, they come with a drive line parking brake. The driveline brake works great to hold the truck from rolling when parked, however it will do nothing in the event of an emergency rolling down the road (other than burn it's internal shoes up). There is no manual, emergency stopping device so it's of great importance to keep the trucks hydraulic braking system top notch. A HD dana 80 rear axle that came from ford with gear ratio options intended for two purposes; Heavy hauling & towing. They came in various wheelbase lengths and are often custom stretched for longer beds; such as for rollbacks (flatbed tow trucks), with up to a 15,000 LB GVWR. It's widely known as the F-450 equivalent with many auto stores listing parts under either name.
These trucks are easy to identify with their pickup size cabs, yet unique F-Super Duty fender emblems & 10 lug 16" wheels.


Axle code 72 = 4.63
Axle code 73 = 5.13 (Most common)

 

if you cross threaded the injectors enough to bugger up the threads, my bet is you cracked the hard line caps too and that is causing the fuel leaks on those injectors.