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The run on or "dieseling" could be caused by the idle speed being to fast.
When you advance the timing the idle RPM goes up so now when you turn the motor off it wants to keep running.
If you bump the timing back up to 10* BTDC and re-adjust the idle speed I bet it wont run on.
I got mine at 12* BTDC and idle speed set to about 650 RPM and I dont have any run on.
It starts right up when hot, no kick back like if timing is too far advance.
On your vacuum leak did you find it yet?
Dont know if it was posted or not but do you have a metal "juice can" on the inner fender for the HVAC controls?
If so try and pinch off the vacuum to it and see if that helps.
I had a vacuum leak and traced it back to that juice can.
It had rust pin holes on the bottom behind the mounting bracket so it could not hold vacuum.
The fix was pull the bracket off the use fiber glass rosin to coat the can.
Paint it black and install bracket and it works like new.
Dave ----
on the carb i opened the idle mixture by 1/8 a turn total, the engine timing is 10* btdc, on the choke chain that connects to the carb i made it as loose as possible.
i noticed if i have it pulled very tight the idle speed is very high while if its too lose the engine wont even turn on. so i have very little tension but the idle is still high. ill try to make it as loose as possible yet have the engine still run.
*edit
i found the vacuum leak a week ago and swapped out that out, it was attached to the main manifold and it ran to the top left there are 2 vacuum ports connections.
i loosened the choke chain even more and the idle is much slower and it ran badly so i readjusted the carb. with a high idle you need 1/8 screw turn on the carb for it to run smooth, for a loose choke you seem to need 1 1/2 turns for the engine to smooth out. i have been testing the truck extensively and stress testing it by driving up and down a mountain pass with a high incline. when i turned the motor off smoke puffed out of the intake and the diesel effect was very aggressive.
the fuel mpg was really bad like about 8-10 mpg, i watched my fuel gauge drop as i cleared a mountain range. i think it holds about 20 gallons in the back tank and 15 in the front.
but back on point, i loosened the choke chain connected to the carb and readjusted the carb idle mix i had the truck warmed up for about 10 min and turned it off and it did not diesel. i have noticed the truck is difficult to start after a few days of sitting. its not the starter that is fine, its the fuel delivery into the carb or some how the carbs bowl is empty and attempting the start the truck primes it also the fuel pump is new. so why not have an option to preprime the fuel into the carb? that makes sense right?
If you have a very large hose nipple on top of the carb bowl that is not hooked to anything, plug that off and see if the fuel evaporation is less when it sits.
I removed the steering box because of excessive play in the steering. I bolted a oem rebuilt one back on. it was a bit difficult to connect it to the frame so i went under the truck and cleaned with a metal brush all contact areas and used a air compressor to blow the dirt + oil crud. after the area was cleaned and prepped when i would thread a bolt into the frame to connect into the steering box it would not contaminate the bolts threads with dirt and oil. its on temporarily right now with all bolts in but i want to take a bolt out and add some assembly lube then put it back in as it was hard to actually mount it by hold it with one arm.
i was unable to remove the pitman arm so i bought a new one but i am unable to reuse the washer and nut on the old box. also i was able to get the power steering lines connect no problem but i am having a terrible time connecting the flex coupler to the steering shaft. the flex coupler has teeth and also the power steering box has a flat bit, i tried to connect on the flex coupler with the gap and get the teeth right. the steering shaft is also telescopic so i line up the flat side of the flex coupler and the flat blade of the steering box and pull and wiggle them on but its just not working. attaching that one thing is harder then all the rest of the work to get the steering box on the truck and lines back in.
i removed and cleaned the castle nut that connected the pitman arm to the steering linkage, ill be removing and cleaning all castle nuts in the steering arms and replacing with new cotter pins.
i saw the steering fluid is dirty so ill have to flush the system.
from this post i have gathered there is a high pressure and low pressure line connected to the power steering box so you disconnect the low pressure line (i am guessing its the smaller hose diameter one) and allow fluid to drain into a bucket. turn the engine on and feed fluid until it runs clear after about 3-4 quarts of atf power steering fluid flushed into the system while moving the wheel right and left.
You might take the old box to a local garage and see if they can remove the pitman arm.
I am sure it will need to be removed before you send it back for a core.
Did you check around the frame where the box mounts for cracking?
Dont think it is a big deal on 4x2 trucks but is on 4x4 trucks.
On the flex try and pry the spline apart some to give more space for it to slip on the box.
Also recheck the splines to make sure of the spacing. I have seen some that have a few missing besides the flat you see.
You may want to remove the flex from the steering wheel side to fit it to the box as it would be easier to fit to the box and then back to the wheel side.
For flushing the pump the low psi side hose has hose clamps on the hose to the metal lines.
If you remove the hose from the box side you can then use that hose to drain the pump.
BTW you should have gone with a Red Head or Blue Top box over a parts store rebuild.
They are a little more money but they replace the bushings with bearings so it is tighter and should not get play like the store rebuilt.
I went with the Blue Top.
Dave ----
I inspected the frame it has zero cracks, i was able to remove the pitman arm about an hour ago and was able to reuse the washer and screw. i got a blow torch and heated the screw and smacked it with a 5 pound hammer, i did that for about 30 min in cycles. i was able to get the screw off using a really big wrench, i had also soaked it in wd-40 over night and would tap it with a hammer when ever i walked past it.
i went back to the power steering box and removed 2 bolts and kept one at the bottom to act as a pivot point. i loosened so i had a bit of play but it would not fall out. after that i got a wrench and twisted the teeth while pulling the linkage forward to line up the teeth that took around 30 minutes and it slipped into place. there is a bolt that connects the flex coupler and the power steering box, i added that back into place but it does not feel tight, the bolt is clearly all the way in but it just does not feel tight and the threads are fine. i cannot screw the bolt down anymore its completely in but it feels like it just turns in place.
the pitman arm was covered in mud and grease so i pulled that off with a puller and i did not mess up any of the teeth. i cleaned it with a metal brush it looks like new and its an original part even has the ford stamp.
i put the pitman arm back on the power steering box, and cleaned all the linkages and inspected cotter pins and none needed to be replaced. there was no thread damage to the large screw that holds the pitman arm in place, i reconnected the steering linkage to the pitman arm and cleaned the castle nut as it was loaded in grease and put a new cotter pin in.
i dont have enough power steering fluid so my reserve is empty but i tried to have the best quality for the job.
i have never heard of a blue top power steering, but they seem to be quality after going to there website. if i had known about it i would have went with that
I filled it up with power steering fluid and turned the steering wheel back and forth to purge the pump and lines of bubbles. it stopped whining about 1-2 minutes of this when the truck was warmed up. i then took the truck around the block and the steering has almost no wiggle in it its like driving like a totally different truck. the truck still needs a wheel alignment but its driving very very smooth. i also bought some carb cleaner and shot it in so i could clean the valve heads and the engine is now running smoother im shocked really at how it changed how its running. i did not know how to clean the valves when i had the engine head off. there is like a special tool you need to get the valve rods off the springs well i dont have it but i do have a 5 dollar can of carb cleaner.
if you look at the third photo if the radiator is forward and that line has a rubber hose is that the low pressure line or the thick metal one aft? i need to disconnect one of them run the engine and fill the pump with fluid until it runs clean.
the next project for the truck is ill be removing the tires and replacing wheel bearings and packing with grease.
It sounds like you are making head way on the fixes
As for the low psi or return line if both have crimped on hose then I dont know what one is what?
I also dont remember when I replaced my box what I did as it has been about 4 years now.
Sorry
Dave ----
The low pressure hose usually has a regular hose clamp on it. It hooks to the steel cooling loop on front of the engine crossmember on the frame.
yes you were right the low pressure hose is the larger hose that is further from the engine and it runs along the frame. i cut a piece of rubber hose and stuck that into a bucket and was able to purge the lines. i did it while the engine was off by pouring fluid into the pump until it ran clean it took about 2 quarts before it ran clean. i was worried about having it on with such low levels of fluid. i filled it back up and tested around the yard and the steering is even smoother now. I also greased the steering linkages with red grease.
because the weather was bad today i did not test drive the truck after making repairs and modifications as it rains pretty bad over here.
if i had known how easy of a fix it would be i would have done this decades ago but everyone told me: "old trucks have steering with a lot of play thats normal" and what did i stupidly do? well i did not authenticate the information
the truck is old sure but there is a ton of companies that make oem parts and repairs on mechanical engines is so much simpler then engines with computers and fuel injection. carburetors are very simple and dead reliable but do not have the fuel economy or precise timing fuel injection. fuel injection is still very reliable but from what i hear its harder to work on and requires a computer to run diagnostics on the engine while its running. so to cut to the chase the truck is not hard to work on just really big, and dirty and some times you need a oxy torch to cut parts off because they are seized.
As for the loose steering on old trucks.
What happens is most new cars and some trucks use Rack & Pinion (RP) over box like our trucks have.
RP is a lot tighter and we get use to it on our DD's so when we drive something old it feels loose.
When I got my new 02 Durango with RP I had a hard time making it go straight after driving a 86 K5 Blazer since new.
As fro EFI yes a computer would help on the newer stuff as they have so much stuff that is controlled by it.
But our trucks as long as you know the measure spec on the parts you can find what might be bad with a meter.
Dave ----
Just saying, (knock on wood), my 86' EFI still works great. Drove it yesterday, after sitting about 12 days, it started right up, (I do let the fuel prime, before engaging the starter) ran fine. Last time I put gas in it, was back in early May. It will sometimes sit for month's over the Winter. I have not had any issue related to EFI... knock on wood. The truck has 140,500 miles on it.
i took the truck into some heavy rolling hills and the engine ran super smooth, the steering was tight and the handling was accurate. its crazy how well it can run with minor tweaks and a few swapped parts. the fuel economy was very good i estimate around 12-15 mpg.
i was thinking of a way to improve my fuel economy and i remembered how planes get better economy for the airspeed and altitude by controlling engine rpm and prop feathering so its operating at the most efficient curve. then when i took that idea to my truck i dont know how to gauge my rpms and i have an automatic transmission. if my transmission was manual i could set it to a lower gear so i could drive slower vs being in a higher gear and drive faster. but my truck does not have a tachometer on the dash board. it looks like ford was thinking about it in the middle console but left it out as it has a hole.
Just follow what the factory did to these trucks in later years. Overdrive transmissions with lock-up, more aluminum in the transmissions and transfer cases, more efficient rear end designs (8.8) and then the fuel injection.
The truck has 140,500 miles on it.
