ozziesironmanoffroad

My F150 has been having some weird issues. At first I thought it was the fuel pump, but then a master tech friend of mine took a look when it wouldnt start, and discovered an aftermarket alarm system. I asked him to remove it, and he said it would be EXTREMELY hard because you have to undo every little thing they did, and if you missed even a step, you're going to have problems. so long story short, he did something, and rewired the kill switch, to disable the alarm, so the truck would start. worked BEAUTIFULLY.

...until today. 6 months after that. it was doing the same symptoms, so I pressed the kill switch, as usual, (it does it every once in awhile), and turn the key. still nothing. so i hold the kill switch, turn ignition off, turn it back on, then start it. crank and crank. sat in the grocery store parking lot for a good 10 minutes. repeat procedure, truck starts 2nd crank.

okay, so i figure its good for awhile. i drive home, turn it off, then decide to test it again. it starts beautifully 3 times, then on the 4th it just stopped. crank and crank. killswitch or no kill switch. twice in one day this happens... and it has me wondering.

does this sound like a fuel pump going out, the aftermarket alarm starting to get flaky, the ignition switch going out, or the key losing its edges? (i heard on another forum i belong to, that these years of F150 and Expeditions tend to have problems with the key rounding off so much its not recognized enough to allow the engine to start).

once it cools down, i will go out there with my voltimeter and see if I can access the fuel pump plugs, and I'll see if it is getting power. i swear, it seems like its just not getting power... but I don't know, as automotive electrical isnt a specialty of mine...

ozziesironmanoffroad

update... the pump is getting the right power, but i have no fuel pressure, and the pump is not turning over. fuel pump.

but heres the kicker: the THEFT light flashes constantly while the motor is cranking. which leads me to believe that the PAT is malfunctioning, or kicking in, whatever...

what i dont get, however, is how the pump is getting power but NOT turning on, if its the PAT disabling the vehicle.

can anyone shed some light on this? im ripping my hair out...

Jgiff

I had an issue like that and couldn't find anything wrong I ended up putting in a fuse box and gem module from the junk yard works fine now

ozziesironmanoffroad

a fusebox and GEM from a junkyard solved your problem?????

ruiterman

If the pump truly has good power and is not running, then the pump is bad.

My truck did the same thing last year. Would randomly not start. Everytime I would check fuel pressure it would be fine and the truck would run great. Finally it went bad enough I was able to check pressure when it wouldn't start.

Replaced the pump and it's running great for over a year.

Good old Bill

Having power to something is only half the testing procedure. No electrical device will work with out a complete circuit, it needs a ground. In todays equipment, most electrical "turn on or off", is controlled by a grounding circuit.

ruiterman

Good point Good Old Bill. If you have no ground, or if you have a broken wire, that would be the same symptom.

I just looked in my Chiltons manual and it shows the fuel pump is switched on the power side by the Fuel Pump Relay. It also shows there is a "Inertia Fuel Shut-Off" module in series with the fuel pump as well. Although from how I read the manual, I think it is probably wrong some where on what the internal circuit inside side the Inertia Fuel Shut-Off module would be. It is obviously a simplification as it shows it as a relay, but it seems to be hooked up wrong.

That aside, according to Chiltons, it appears the Fuel pump is "hot side" switched and if the Ineria Fuel Shut-Off is triggered, there is a "Fuel Reset Switch Indicator" that would come one.

weeda68

I am not sure about newer ford trucks, but i know a lot of ford cars in the mid 90's have a fuel shut off switch. It was installed for easy fuel shut off in case of an emergency. However I know the circuit can overload and throw the switch causing your the pump to not turn on. Most of them just had a reset button you pushed and then they started working again. Not sure if this is the case, but it is always a good thing to look into before you start shelling out the time and money of installing a new fuel pump.

bobkyle2

Your problem is a system called PATS ... Passive anti theft system... Make sure your key is like super clean.. Or try a different key.

garbill2003

That switch is usually located behind the passenger side kick panel most of the time its writer their and I had a aftermarket security alarm in my jeep wrangler and it shorted out and almost caught it on fire was good when I had my kids with me never buy a vehicle again with a aftermarket alarm