Intermittent dieseling

[dodgerammit]

Hello all. As of late, I have ditched the electric pump in favor of originality.

Since then, I have noticed an occasional dieseling scenario. Every few shut offs, the engine will sputter a time or two before stopping.

Otherwise, everything is running fine. Temps are about the same the last few days. Mid 80s to low 90s.

What should I be checking out?

Thanks.

[Tatsadasayago]

Dieseling is a result of excessive cylinder head temperatures. The exhaust valves may be running hot and when you shut the engine down they act like glow plugs. Running too lean is the usual cause and that can be fixed with some carb tuning. Since it sounds like this problem arose after going back to a mechanical pump, I'd suggest that your float level has dropped due to lower fuel pressure. Reading your spark plugs will tell you quite a bit and I suggest doing that first. If you see grey or white on the plug instead of a tan/orange your engine is running too lean. If they are tan to dark brown, I suggest you read further.

Sometimes it's carbon buildup in the chambers that's the culprit. This is often caused by ring or valve guide oil leakage into the chambers. This can sometimes be corrected by using the Water Injection Cleaning Method.
For a short period of time, pouring a small but steady stream of water into the carb while running the engine at 2500 RPM will increase the cylinder pressures significantly and often breaks carbon deposits loose. You don't drown the engine, but as you pour out a 12-16 ounce bottle, the RPM should drop about 500 or so. The duration of the pour should be short. There is a risk of damage to the rings and valves if you pour too much water too fast so you have to find the balance between pour rate and duration. Listen to the engine as it will tell you when you are pouring too much too fast as it will begin to shudder.

[Curly]

Check your idle speed. Idling too high will also lead to dieseling.

[az chip]

Did you just install a new ignition? May need the diode in the alt wire.

*You installed a streetfire. Check instructions for adding the diode to the alternator wire*

[dodgerammit]

Check your idle speed. Idling too high will also lead to dieseling.

I'll play with my idle first. If it continues, I'll pull the plugs (installed less than 800 miles ago) and give them a look.

[dodgerammit]

Did you just install a new ignition? May need the diode in the alt wire.

*You installed a streetfire. Check instructions for adding the diode to the alternator wire*

No, no. That doesn't cause dieseling. That gives you run on.... indefinitely. lol

[az chip]

Did you just install a new ignition? May need the diode in the alt wire.

*You installed a streetfire. Check instructions for adding the diode to the alternator wire*

No, no. That doesn't cause dieseling. That gives you run on.... indefinitely. lol

Some people confuse the two.


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[dodgerammit]

Pulled a plug. No dark coloring and no white. Just a small area of orange/light tan. I backed the idle off a bit more and drove it just now. After setting timing with a vac gauge, the engine was nice and warm. 3 shut downs with no dieseling. Hope to be good to go. Thanks all

[kansasboy001]

If idle mixture isn't correct your idle screw will have to be too far open and will cause dieseling. Not enough base timing can cause too. Throttle plates shouldn't be very far open at all. Causes carb to run off of main circuit instead of idle circuit. If you're on a higher altitude youll need 15degrees base timing.