My truck is doing something weird

[Old Broke Cracker]

Hey ,Its me the new old guy I know in years past I've run into this but I can't remember what I did to correct it.. My 84 with a 350 - Q jet when I shut the truck off it keeps running, I can hear the engine slow down but it won't shut off even when I put it in gear it still runs for 10-15 seconds .. I was thinking a bad alternator or could it be a cracked head ? ( steam) . I know MSD's etc can cause this but mines all stock ... any ideas ?
I did drop the exhaust today to install some headers - I was thinking maybe pull the heads ( I have a set that is redone on the shelf and put an Edelbrock intake on it . This should do ok until I can build a motor some other time. I did take pictures today of my rides I will post them this week if I get a chance, I've been working OT lately .. Thanks for any input

 

[bucket]

You mean it runs on or "diesels"?

Check the timing and the idle speed. In the mean time, if it's an auto, shut it off while in gear. The slower idle speed and slight load should keep it from dieseling.

 

[Old Broke Cracker]

Thanks I'll do that - it seems to idle ok ( not too high ) even when I shut it off I can rev the engine and it rev's like the key wasn't shut off, ( I mean it revs high - missing a little bit but rev's pretty good ) no pinging or detonation etc
I am going to switch the intake and carb - while installing the headers - wasnt sure if it could be a head issue ( while I was there) Thanks

 

[MisterB]

Check your idle. Also, might be you're running too rich, and the carb needs to be leaned out. Have you started using different octane fuel? Have you started using ethanol based fuel? They might be effecting how your carb runs.

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[80BrownK10]

So you can keep reving it and it sounds normal except a few misses?

Do you have the right heat range spark plugs in it? Too hot of plugs they will act like glow plugs and keep going. Also check ignition connections to make sure it's shutting your ignition off with the key. But my guess is that is if it eventually stops the ignition is off. I'm guessing a timing issuer with idle speed/carb adjustment. But have you changed plugs recently or not at all and have some crappy carbon filled plugs?

 

[78C10BigTen]

Anybody but me thinking faulty key switch??? When you turn it off does everything in the truck shut off as it should?

 

[80BrownK10]

Anybody but me thinking faulty key switch??? When you turn it off does everything in the truck shut off as it should?

That is one of my thoughts. You could disable the ignition while running to see if it keeps doing it to eliminate the ignition as the faulty component (would eliminate it all key switch, and ignition components)

 

[Rusty Nail]

I don't know nothing about no distributor run-on or no fancy ignition switches, I reckon it's gotta be one of them goblins like was on the **** there.


Sounds like all it could be to me..
Don't ya think?

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[Old Broke Cracker]

Hey Guys Yeah I thought I could pull the wire off the HEI while it was running and see what it does and or off the distributor and see . when It is running and I shut off the key the gauges shut off etc , the engines changes idle etc but won't shut off - Its doesn't diesel, ping, make any noises etc just looses power and keeps running ( kind of rough but not terrible -
I pulled the exhause off of it to put on some headers - I may - go ahead and bolt the headers on and see If I can find the issue - and maybe save me some work - pulling the heads - The reason I question if its heads or not is - It runs around 200 deg with a new radiator - But I will be getting a new Champion rad soon , and also when I bought it the guy asked If I made it home ok and no heating issues - which it didn't .. But why ask? Ive had the truck now for about 4-5 years and slowwwwwwwly restoring it - haven't driven it much - interior is almost done , I put a 12 bolt and a 3:40 gear, built a 400 turbo ( I used to be a trans builder 20 yrs ago) now the exhaust and then an engine,, I have a 400 on the stand and started cleaning .. It will take another year or so before I can start building it Im too broke actually My well is giving rouble here at home and looks like I'll need 3k soon as well as a new shop roof - Go figure - I'm a builder and my stuff never gets done until its too late. Thanks TTYL

 

[MisterB]

I could be wrong, but here's how I see it. You need to adjust your carb. Whether it's the idle, lean/rich mixture, or both I think that's your problem. A couple weeks ago when I was dialing in my carb, there were a couple times l got something off a bit, and it would diesel on after turning off the key. I would think if you give it gas at that point, it'll run longer, even with the key off. The gas pedal is nothing more than a cable attached to the carb that squirts more fuel in when depressed. I would think you can do this after the key is turned off (which helps to keep it running longer as it diesels along), just as you can do it before the key is turned on to set high idle and squirt some fuel in the carb to help it start when cold.

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[Old Broke Cracker]

Great Movie clip Rusty

 

[Snoots]

Why install headers now if you're going to put new heads and intake on it? Just curious.

If it were me (and it ain't) I'd pull the cap and see if the advance springs are hung up.

 

[Old Broke Cracker]

well I was really pushed for time , working OT and just need it running - But I will be pulling the head- I wont be saving time by doing it twice. Just found out today I have to work again this weekend.. Thanks for the reply

 

[Rusty Nail]

What happened to cause the change? It was running fine or?

Bad gas. Suck it up and check the cap lol. We'll see it thru Cracker, dont fret.