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BLown Fuse #18 PCM, fuel injectors, IAC, MAF, fuel pump relay

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Old 08-03-2014, 08:09 PM   #1
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Default BLown Fuse #18 PCM, fuel injectors, IAC, MAF, fuel pump relay

So, I was climbing a gravel mountain road in my 99' F-150 XLT 4.6l 2wd yesterday and the engine suddenly died. Truck would crank but wouldn't start. With the ignition on the theft light was flashing and one of the fuel relays in the junction box under the hood was clicking rapidly.

After a rather embarrassing tug off the mountain from a Chevy, I found that the #18 fuse in the under hood junction box had blown. Replaced the fuse and made it home the rest of the way. Got home and checked the wiring diagram and found fuse 18 powers all the injectors, IAC, MAF, PCM, and the coil side of the fuel pump relay.

Thinking that a wiring problem was more likely than any of those components shorting intermittently I started inspecting the wiring harness and moving it around with the key on and finally found it. Turns out a sharp corner on the driver's side rear of the intake manifold rubbed a hole in the engine harness right below the fuel lines (very center of pics). It looks like the harness is routed where it is supposed to be from factory, all the plastic clips that hold it on are still there, even on the very back of the engine. So at this point I'm beginning to think WTF Ford? Maybe that sharp corner was supposed to be rounded off? Or the harness is actually in the wrong place? Has anyone else here had this happen or heard of it happening or do I just have a freak truck?
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BLown Fuse #18 PCM, fuel injectors, IAC, MAF, fuel pump relay-dsc_2828august-03-2014.jpg   BLown Fuse #18 PCM, fuel injectors, IAC, MAF, fuel pump relay-dsc_2829august-03-2014.jpg  
bigscurrybear is offline   Reply With Quote
Old 08-03-2014, 08:09 PM

cranks but won't start, ecu fuse, fuse #18, no start, wiring harness

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