1990 7.3 international ?

I don't know where to post this so please understand. I have a 1990 Ford super duty with a 7.3 non turbo. It has 74,ooo miles on it. It will start right up run for 30 seconds and stall just like the key is turned off. It takes 1 to 2 minutes of cranking for it to start again. I changed the fuel filter, that didn't help. After it restarts it runs fine, until it sits for more than a hour then it does it again. Thanks Al

Sounds like it's sucking air somewhere.

Could be..... orings on the tops of the injectors go bad, and let air into the system and let the fuel drain back into the tank.. very common,,, go to youtube, and look at a video on replacing the orings,,,, not complicated. not expensive,,but awkward to climb on top of the engine to get to them. iirc there are two orings on top of each injector.


Also on that model,, the water separator will get crud in the bottom, and the drain valve is know to let air back into the system and will do exactly the same thing. It ironically has an oring on the drain valve as well....



Also,, the primary fuel pump can fail on the side of the engine and cause that problem...


listed in order of probability...

Put an electric in line fuel pump on it between the filter and the lift pump.

Engine driven Fuel pump on side of engine. replaced about 3 pumps on mine. just up and quits running have to crank and crank before it fires. have had it drain batteries before it will start. replaced fuel pump and problem goes away. that is just my issues with my 93.

First thing I would do is change the return lines on top of the injectors, as well as the o rings. Every one of them I have ever messed with, the return lines leak and then you fight starting it.

I second the return lines and o-rings under the tees. If it starts then dies, you're likely losing prime somewhere. I suppose the mechanical pump is possible, but seems like truck would not restart, no matter how long you crank it.

I have a 86 with the 6.9, a 91 with 7.3 and a 92 with 7.3. The hoses and o rings on the return lines dry out pretty regularly it seems, and sometimes it won't even show any good signs of leaking, but just a little air will cause the problem you are having.

The hose that comes with the return line "kit" that you can buy at just about any parts supplier seems to be less than par, usually lasts 2-3 years. I have started replacing the hose with diesel approved regular rubber line, and it seems to last a little longer. I also go get the o-rings for under the tees at my local diesel repair place, usually costs me about $10 for the 16 required o-rings. I've been lucky enough to only have had to replace tees once on the 86 truck.

I'd look for a obvious leak, and if none found, that would be my first repair. Fixed my 86, and my issue was very similar to yours. My 92 also did very similar, but there was NO DOUBT the return lines were leaking that time.

Brad

I have a 1994 7.3 IDI turbo with the same basic engine (last ones sold in early 1994). Ford had many service bulletins out that dealt with the type of problem you mention. I.e. "fuel drain-back." There are two one-way check-valves in the fuel system that need to work. One in the fuel-pump and the other on top of the injection pump. Also, the Schrader-valve in the filter assembly was prone to leaking.

Return lines x3. Go to oilburners.net, more than you will ever need to know.

I have changed the caps and O rings on my 94 twice and it is starting to need to be cranked quite a bit after setting over a weekend. It also takes more cranking in the mornings week mornings. After the first start it starts like turning on an electric motor. Not that big of a job normally but I am putting it off because of my crippled hands. This being a cab over van it is done from both the front and from the inside of the cab. I have always cracked some of the caps getting them off. On this 94 the slightest air getting by the O rings lets the fuel drain back some. Kind of a common task in this non turbo 7.3.I bought the O ring/cap kit at the auto parts store.

I agree with return line o-rings and hoses. I had the same truck years ago and wish I had kept the engine out of it. Body was falling apart after too many WI winters as a daily driver. There was also a return line from the filter with a check valve that would fail causing the same problem. I was told to eliminate the line and plug the port in the filter as it was only used when bleeding the system (self bleeding). After that if run out of fuel, I would have had to bleed it manually with the schrader valve while having someone crank the engine. It did fix the problem.

Good points above on common idi probs, another thing to add, if I didn't miss it is the fuel heater and o-rings in the filter head. I have seen these leak and cause air to enter the fuel system. You can take the filter head off and pull the heater to replace the o-rings. Its a simple, quick and cheap fix if needed.