Engine Dying
New User
Joined: Mar 2001
Posts: 12
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Engine Dying
I've encountered a problem. My 87' F-150 seems to idle real low and then kick back up real high just at idling, its this way no matter hwo long it runs. For example the tach may read 800-900 and it sounds like the motor is gonna stall then it will shoot back up to 1200 roughly around there and sound fine. It just keeps surging between those two ranges. What could cause this? Is this the way fuel injection is on the inline 6. I've poured fuel injector cleaner into my tank, no difference. Any help will be appreciated.
Junior User
Joined: May 2001
Posts: 63
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Engine Dying
If you can't find a vacuum leak, the next thing to check is the thermactor air bypass(TAB) solenoid and the thermactor air diverter(TAD) solenoid for proper operation. They should be on the driver side of the motor mounted just below the valve cover. If you have a Code Scanner, run the check and see what codes come up. You will probably get one related to the Thermactor air system always flowing upstream. I have had this problem before and it drove me nuts until i was able to find and fix it.
Elder User
Joined: Apr 2001
Posts: 772
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From: Glen Burnie Maryland
Engine Dying
My '87 was doing basically the same thing. Removed the Idle Air Bypass valve (on top of the Throttle valve). Can of carb cleaner thru that to clean it up and the throttle valve, and idles right at 720.
I'd tighten down all the fittings for the intake and double check all the vacuum lines too.
Larry
I'd tighten down all the fittings for the intake and double check all the vacuum lines too.
Larry
