Truck Trend Garage: 2004 Ford F-150 FX4 No-start Failure
Question: I own a 2004 Ford F-150 FX4, and I have a problem the dealership cannot solve. Sometimes the engine won't start. The dealer replaced the computer for the motor-management system and switched off the alarm system. This repair helped for two weeks, but now the truck won't start again. I'm in Holland where there aren't that many F-150s, so the knowledge is limited. My truck has been in the garage for about four weeks, and I'm a bit desperate.
Answer: Hope the condition is happening more often by now or, better yet, continuously. That makes diagnosis much easier compared with a rare, intermittent problem. I'm not coming up with any super-common no-start failures on the 4.6-liter or 5.4-liter engines. So it's going to require a good technician with some patience to figure it out. He'll need to determine what's being lost: fuel pressure, ignition spark, fuel injector pulse, or a combination of those three. If the techs can duplicate the condition in the shop -- even on rare occasions -- they should next fully wire the engine. That means install a spark tester, a fuel-pressure gauge, and an injector-pulse test light. This way, when the engine is cranking and not starting, they can see exactly what's missing. This can, if nothing else, narrow down the potential causes. Also, if all the vital stuff is present during the no-start, this may lead to another area, such as a powertrain control module update, carbon buildup on the throttle plate, or contaminated fuel. The technicians should have the option of installing a scanner and doing a data snapshot. This involves hitting a button on the scan tool when the problem occurs, so they can go back and view the computer data before and after. There are many possible causes. It's a question of accurate testing and process of elimination.
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