I am having a bit of a problem. Sometimes when i shut off my truck, it sputters or fires a couple of times before completely stopping. One time it actually almost started itself back up. I think it may have something to do with the clutch. Usually pumping the clutch a couple of times before turning it off does the trick. Any help or ideas would be greatly appreciated.

 

It's called dieseling, the gas gets ignited from the heat in the combustion chamber and keeps the engine running. A high idle speed usually causes it.

 

My truck does idle high so that would explain it. thank you sir.

 

Its weird i have the same issue in my 1985 f250 HD and my idle is only at about 600-700rpms . Doesnt happen all the time but happens most the time.

 

Welcome to FTE.
Is this auto or stick truck? If auto is that 600-700 in gear or out?
What heat range are your spark plugs? If too hot they can become "glow plugs" and could be the cause.
Also a lot of carbon build up on top of the pistons as it stays hot to burn the fuel being pulled in.
That is why you don't get much run on with EFI as the fuel is cut off along with the spark.
Dave ----

 

its a borg warner t19 manual ,460 ci ,carborated(still has all the emissions junk on it which im getting rid of soon) and im in neutral when shut off. For the spark plugs they are the normal motocraft plugs nothing special. I havnt checked for carbon build up yet so ill have to look at that. Would timing be an issue ? I keep getting told the timing is fine because it passed emissions perfectly last time.

 

Check if you have any problems with your vacuum lines. Not sure how similar your 85 460 is to my 83 300, but I had two lines switched which caused me to have to turn the idle speed screw way in to keep the truck running. With the throttle so far open it caused it to diesel when it shut off. Now, with the lines in the right order, it hasn't happened since.

 

Okay ill go ahead and check that too. Thanks guys i appreciate it.

 

Already so today i was checking under the hood and going through everything it looks like the pvc grommet that the elbo fitting goes into was pretty loose in it. So makes me wonder if theres a vaccum leak there ?

 

 

Timing advance vacuum hose was cracked and brittle. Its funny how that little fix has made it run a little better and stop the really bad dieseling i was getting still rough shut off though. Was going to replace the pcv grommet anyways but then hit a road block with the emissions tubing getting in the way. So thats great. But oh well its all coming off anyways. Btw i got a solid 9mpg today guys 😂 feelin pretty happy bout that😆

 

Hey not bad!
9 mpg... that's a 12.5% margin above average!

 

Hoping once i eventually do a ZF5 swap might improve it to atleast 10 or 11 mpg.

 

Needs more octane. If not getting any detonation you cna also check timing, idle RPM, and that carb is not boiling fuel (a phenolic spacer may help).

 

I dont have an issue with detonation. Starts up everytime with 1 crank ever since i replaced the cracked timing advance vacuum line it hasnt dieseled since. Its weird that it fixed it lol