So just purchased a 1992 7.3 1 ton a while ago. Great truck for what I paid for it, however it has been giving me a weird issue lately.

It rolls far too much coal when driving normally, seems like someone has turned up the fuel on this truck, but not sure....but anyways the problem is when going up a hill in a lower gear getting close to redline it will all of a sudden start puking out GOBS of black smoke, literally making the road behind me disappear, and when taking my foot off the pedal it continues to rev up way past redline. The only way I manage to get it under control is to shut the key off and than back on, and after playing with the throttle a little it will start to get back to idle. Once at idle it is rough for about a minute, but eventually it gets back to normal and I can drive off as though nothing happened.

Am from the cummins world and therefor know nothing about these ford diesels. But to me it seems like a partial fuel runaway, and am curious to see what you all think. Am not against putting in a new fuel injection pump, but would like to see if it is a problem I can fix without throwing a pile of money at it.

Thanks for any help you can lend.

Cheers

 

Sounds like A, the fuel screw was turned up too much, and B, the metering valve or governor assembly is sticking.

You'll want to pull the top off the IP, and take a look inside.
Ignore what changes I'm doing here, but I do identify the parts etc. that you'll see.
Everything should move freely; make sure the metering valve isn't sticking somehow at the end of it's travel.

 

Thanks for this macrobb, will dig in tomorrow and see if this is the problem.

Would like to turn the fuel down too, think I found a decent read up on how to do it. Any advice before I dig into that can of worms?

 

Before you pull it apart, I recommend you

1. Warm up the truck.
2. Go get your favorite Diesel Additive Cleaner/Lubricator.
3. Double or even Triple the mix of cleaner/lubricator in the tank while you are out getting it, drive it for a bit, then to home.
4. Shut it off.
5. Pull the filter.
6. Pour it out. (In an environmentally safe manor)
7. Fill it up with your choice of Diesel cleaner/lubricator that you picked up. (Diesel Kleen or whatever) Only through the small holes, not the center.
8. Re-Install filter.
9. Start the truck.
10. Let it run for 1 minute.
11. Shut it off.
12. Let it set for awhile ... Pretty much longer the better, to a point.
13. Then take it for a ride.

The point is to get the cleaner/lubricant into the Injection Pump and let it set for awhile. ~12 hours is best.

It should clear up within a tank fuel.

-Enjoy
fh : )_~

 

as Festus said, try cleaning the injector pump first.
i prefer to use automatic trans fluid. i fill the filter, and start the engine letting it idle for 30 to 45 seconds then shut it down and let it sit. as said the longer the better. i like to let the ATF sit in the pump for 2-3 days to really do it's thing, then fire it up and go for a good run.
it is amazing how good it will run after an ATF cleaning.

 

Thanks guys, will give this a go before I do anything. Will try the atf first, since I have this in the shop already.

 

I agree with ATF, it is the old school Diesel Lubricator/Cleaner ...

However I find things like Diesel Kleen work faster and better for the heavy work.

ATF works better as a preventive then a sledge hammer cleaner.

JMO

-Enjoy
fh : )_~

 

Well did an oil and filter change yesterday and noticed that there was a lot more oil coming out of the pan than should have been, a bunch more than 10 litres. Looks like I am leaking fuel into the crankcase from somewhere. Always warm up the engine before doing an oil change to thin out the oil and get as much of the old stuff out as possible, was only about 5-10 minutes of idle and driving, and the oil was incredibly hot coming out of the drain, which again leads me to believe fuel in oil since thined out oil would heat up far quicker.

So far from reading around it seems like the culprit could be the lift pump, injection pump or injectors leaking fuel into the crankcase. Any other possible culprits? From reading it seems as though the lift pump has a drain to keep diesel from going panside, so possible a seal in the injection pump. Another thing am noticing is the truck is taking a few more cranks when cold to fire up, which could mean lift pump?

Also took off the air filter and noticed a lot of oil in the intake manifold, also excessive oil in the cdr valve. Not sure if this was the cause to my runaway like problem, but am leaning towards most likely not sense I was able to control it with the key, and if it was running on engine oil it would not have stopped. Put some atf in the fuel tank and put diesel kleen in a fresh fuel filter, let it run for 45 seconds and is now currently sitting for a couple days.

Just doing some reading on these engines and learnt about cavatation, so will be checking the coolant tomorrow to see if I can see any oil in there, fingers crossed that the right additive was put into the coolant by the owner previous.

 

I would replace the lift pump. They have been known to leak fuel into the crankcase when seals fail

 

correct. when the diaphragm in the lift pump fails, it can and usually does leak into the crank case filling the pan with a fuel and oil mix.
if the CDR is full of oil and letting oil into the intake, it most likely has failed and needs to be changed.
cavitation is where a cylinder leaks an fills with coolant.
oil in the coolant or coolant in the oil is most often caused by failed o-rings in the oil cooler.

 

To be fair...
If you've got a ton of oil in the crank case, the engine is going to be splashing it everywhere, resulting in a lot of little droplets of oil in the blowby vapors.
Also, I've never seen an IDI *without* oil in the cdr and intake; there's a reason that the factory specs have a different tolerance on the rearmost cylinder bore.
I'm not saying it's just fine... but be aware that even with a brand new CDR, you will be getting oily vapor into the intake.

 

true. i was referring to his comment that the CDR was full of oil.
that usually is because it has failed due to old age.
i am on my third or forth one in the 88.

 

Thanks for the insights you guys, am learning lots about this old beast.

Had actually thought that the diesel in the crankcase could possibly be the culprit for the runaway like symptoms, combined with the shot cdr. Being such a high level and thinner oil, as well as being smacked by the crank and splashing about, would make sense that a lot of oil droplets like macrobb mentioned would migrate up into the intake through the cdr. During higher rpms the crank would really make a mess in there, and this is when the problem starts to take off.

 

However... if you can kill the engine by turning off the key, it's not that. Why? Because even if the engine is "mostly" running on oil from another source, the injector pump will compensate by reducing fuel. If you can kill the engine with the key, the injector pump has to be providing enough of the fueling to make it stop, which means that the governor assembly should have prevented the runaway...
So even if you *are* getting diesel/oil sucked into the intake, the governor in the IP is still sticking.

 

With any luck the dieselkleen sitting in there for a couple weeks will take care of any sticking.