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Classic Car Service
Classic Car Service, Classic Car Mechanic
Category: Classic Car
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My 1978 Toyota Dolphin (truck) 20R engine has smoke and

Customer Question

My 1978 Toyota Dolphin (truck) 20R engine has white smoke and smells of unburned gas. When its warmed up and idling it makes a sputtering sound (like its getting too much gas).
Submitted: 1 year ago.
Category: Classic Car
Expert:  K. Wiggins replied 1 year ago.

Hello, white smoke is a sign of water in the combustion chamber. This will cause a misfire, resulting in unburnt fuel and a sputter at idle.

I would suggest pulling the spark plugs and checking for any that look fuel or water soaked. Turn the vehicle over with the plugs removed and see if you have water coming out of any of the cylinders. You can also perform a compression test to se if any cylinders are off.

Let me know what you find and I will be happy to help further if needed.

Customer: replied 1 year ago.
I suspect the water leak is coming from the carburetor (the warm up system). Could that be?
Expert:  K. Wiggins replied 1 year ago.

Very possible and common on these older trucks. Often times when restoring these vehicles I tend to go with a weber carb to eliminate that system and improve tuneability and performance.

Customer: replied 1 year ago.
No evidence of water on spark plugs no evidence of unburned fuel either - can you instruct me on how to do a general carburetor adjustment/diagnosis.
Expert:  Classic Car Service replied 1 year ago.

Hello. Different expert here. Could you please post a picture of your carb? I may have additional information for you. Thanks

Customer: replied 1 year ago.
Sure thing.
Expert:  Classic Car Service replied 1 year ago.
Has this carb been recently rebuilt?
Customer: replied 1 year ago.
Expert:  Classic Car Service replied 1 year ago.
Please look at the clear glass window in the front of the carb. Where is the level of the fuel. Low, middle or high?
Customer: replied 1 year ago.
i can't really tell but it looks middle.
Expert:  Classic Car Service replied 1 year ago.

In the last picture sent, locate the center screw with a spring on it. Counting carefully, turn it counter clockwise, counting each full turn. remove the screw. Examine the end of the screw or send a photo. See if the end of the screw is blunt or a sharp point. When you put the screw back, make sure you have the right amount of turn inward as you removed it.

Customer: replied 1 year ago.
OK it will probably be tomorrow
Expert:  Classic Car Service replied 1 year ago.
Ok. Please let me know.
Customer: replied 1 year ago.
looks darned near perfect
Expert:  Classic Car Service replied 1 year ago.

On the front of the carb, to the right of the glass window is a vacuum diaphragm. See if it smells like gasoline inside of it.

Customer: replied 1 year ago.
not at all. I went back to the float bowl idea because it was uncertain. I cleaned it and looked in - the gas is below the window.
Expert:  Classic Car Service replied 1 year ago.

Let's put it all back together and start it up. Observe the fuel window. Then move the screw in and out a turn either way and advise if the engine runs differently

Customer: replied 1 year ago.
it does affect the engine performance - the fuel is dead center of the sight glass.
Customer: replied 1 year ago.
it does - i believe this needs to be adjusted - can you help me get it adjusted to optimal?
Expert:  Classic Car Service replied 1 year ago.

Please tell me how many turns it takes until the screw stops ...Go slow and gently. Do not force the screw in too far. Count the clock wise turns until it stops.

Customer: replied 1 year ago.
7.5 turns in to screw in;
Expert:  Classic Car Service replied 1 year ago.

Please reset the screw to stop at 4 1/2 turns then retest

Customer: replied 1 year ago.
ts idling normal now, its kinda sputtery, but I'm not sure if thats just because its cold.
Customer: replied 1 year ago.
its ...
Expert:  Classic Car Service replied 1 year ago.

Is the air cleaner installed? This is very important that it is in place

Customer: replied 1 year ago.
its installed
Expert:  Classic Car Service replied 1 year ago.

Let the engine cool. off completely when cold, remove the lid of the air cleaner and start the engine. When it starts to sputter place a rag over 1/4 of the choke plate opening. See if the idle smooths up.

Customer: replied 1 year ago.
Let the engine cool. off completely when cold, remove the lid of the air cleaner and start the engine. When it starts to sputter place a rag over 1/4 of the choke plate opening. See if the idle smooths up. tomorrow

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