Fast Idle. What to do
- Thread starter TOBASH
- Start date
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If the system hasn't been "fiddled" with, the only thing that tends to just "go bad" is the diaphragm - in which case you'd have to replace it.
If you or the previous own was tinkering, however, there are several places you can adjust things:
- Check that the hand throttle allows the pedal to return to rest, it can be adjusted by loosening the clamp at the very end of the hand throttle cable jacket.
- Check that the main throttle cable is allowing the butterfly valve to rest against the stoppers when you're not on the pedal. It can be adjusted with the two nuts holding it on top of the valve cover.
- Be sure there are no vacuum leaks in the hose from the butterfly valve to the injection pump
- Adjust the stops on the butterfly valve to allow it to close more.
Even after replacing the diaphragm, and adjusting all of the above, I still had to adjust the butterfly valve stops to bring my idle down.
i just put a 2h in my truck and the first week i notice it was idling high 900-1100. when under the hood, i notice when i would hold the throttle cable rod the motor would settle and idle proper. the problem was hold/missing spring in the linkage. i found some little springs around and put them on and she purrs at 600 now
i had the local toyota dealer print up a diagram of the linkage, that how i found out what was missing
check springs, hopefully its soemthing simple like that for you
i had the local toyota dealer print up a diagram of the linkage, that how i found out what was missing
check springs, hopefully its soemthing simple like that for you
- Thread starter
- #4
So, before I spend hours going over the engine manual, might I ask several questions?
Where is the diaghram and how is it tested?
I notice that the engine idle picks up and idles fast when the engine is warm, and is not fast when cold. What is that indicative of?
I am new to Diesel engines, so I only have a basic understanding.
Thanks in advance,
T
Where is the diaghram and how is it tested?
I notice that the engine idle picks up and idles fast when the engine is warm, and is not fast when cold. What is that indicative of?
I am new to Diesel engines, so I only have a basic understanding.
Thanks in advance,
T
See Beast II's link for a pic of the diaphragm.
Its located inside a cover on the back of the injection pump - you'll know you're looking at the right spot because there will be a hose leading out of the cover, going up to the intake manifold.
You can test the diaphragm by pulling the hose off the intake manifold and sucking on it (note there are two hoses, pull the one that attaches to the END of the diaphragm cover). If you can pull air through it continuously, it needs replacement - there is a spec in the FSM, but its something like it should be able to hold a vacuum for 10 seconds or something.
But... test the other adjustments first. Multiple things can be wrong simulatenously. Even with a good diaphragm, a 3B's idle point goes up as the engine warms.
