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tatsura123

10-05-2010 07:20 PM

Trucks dying, where to start?

I recently bought an 89 F150 4x4 with a destroyed 351w in it so I bought and rebuilt a motor and put it back together. The truck runs great except when I break quickly from 45mph or faster the truck dies. I think there's a vacuum leak but don't know where to start. Anyone got any ideas

Steve83

10-06-2010 03:23 AM

More likely a problem with the IAC, or someone tampered with the throttle stop screw. When you stomp the brake at speed, the EEC drops the IAC to provide more engine braking. Yours apparently is closing too far, killing the engine. Read this caption & the links in it:

https://www.supermotors.net/getfile/...b970905iac.jpg

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