"Dieseling" Concern- Carburetor knowledge required :)

Hi,

I've got a 90 Tercel that's got a severe "dieseling" problem (engine tries to run despite the key being in the "engine off" position). The only thing unique is the fact that it *only* occurs at normal operating temperature, and the problem seems to be accompanied by acceleration-from-stop problems, specifically, the car accelerates very slowly in the lower gears and shakes like it's misfiring (again only at normal operating temp).

From what I understand, the usual suspects are:

*Carb choke/jet *Fuel cut solenoid valve *Incorrect ignition timing

I tried to perform a timing check, but I can't adjust the idling speed down to 900 from 1100 (Toyota claims 900 is the maximum allowable speed for a timing check). Other than that, all vacuum lines (and there are LOTS of them) seem secure, the spark plugs are rich with fuel, the car gets lower than expected mpg, and it's very difficult to get the engine to turn over immediately after it diesels (though it will crank for a couple minutes before it finally turns over, probably due to cooling down from normal operating temp).

Any suggestions would be greatly appreciated, and I'll be watching this topic with great interest. Thanks! :)

Reply to
Jemal
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Unfortunately, the carburetors on that vintage Tercel are a bear to work on.

It sound like the carb is running very rich. The misfire could be from soaked spark plugs or cheap spark plugs. I recommend genuine Toyota ignition parts.

See if the butterfly valve (choke) is in the open (mostly verticaly) or closed (mostly horizontal) position when the problem is occuring. With the engine warmed up, the butterfly valve should be open. If it it not, then the choke pull-off might not be working or the linkage could be gummed up.

If the choke is open when this is happening then a jet may be leaking.

Check your air filter to make sure it is not clogged. To do this, shine a light behind the filter element. If the light is dim when you look through the paper, replace the air filter.

Since you have a problem when accelerating, I doubt if the fuel cut solenoid is the main cause.

Incorrect ignition timing is not high on my list of suspect causes.

The idle speed is probably too high because there is too much fuel being delivered to the engine.

Reply to
Ray O

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