'94 F-150 - stumbles off-idle with back smoke


Old 06-18-04, 02:41 PM
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Join Date: Apr 2002
Location: United States of America
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'94 F-150 - stumbles off-idle with black smoke

Please help! The '94 Ford F-150 I just acquired is going to have to help me move this weekend, and it picked today to start acting up. The truck has the 4.9-liter inline 6 cylinder engine, fuel injection, and 4-speed auto trans, with 105,000 miles on the odometer. When I started the truck this afternoon, it started and seemed to idle okay, but its response to any throttle was to stumble (sometimes to stall on sebsequent restarts) and belch thick black smoke from the tailpipe. Upon popping the hood, I was greeted by a strong smell of gasoline. running a "key on, engine off" MIL test, I got a code 111 (system pass) and a code 628 (E4OD converter clutch error), but nothing about the fuel system or engine. My first guess, based on symptoms, is that I'm looking at either a throttle position sensor problem or a MAP sensor issue, but I don't know how to go about testing either of these components or if I'm even headed in the right direction here. Also, can I conduct a "key on, engine running" test with only the MIL to read, or can I do it with an analog multi-meter? If so, what's the procedure? Based on the info in my Chilton's manual, the truck runs on the EEC-IV system. Any help will be greatly appreciated! Thanks - Chris
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Old 06-18-04, 10:45 PM
Join Date: Dec 2001
Posts: 2,538
start by checking fuel pressure and also pull off the vacum line on the fuel pressure regulator and cycle the key to see if any fuel runs out of the regulator that may be causing the engine to flood, there is a fuel pressure test port on the fuel line at the rear of the engine on the right side near the firewall.

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