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ttiger79
ttiger79, Auto mechanic
Category: Ford
Satisfied Customers: 1257
Experience:  ASE Master Certified, Advanced Level Engine Performance
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2002 f150 cranks over but wont start

Customer Question

cranks over fine, drove to work fine. tried to reset the fuel pump shutoff switch button didn't click. truck wont start, can't hear the fuel pump when key is on
Submitted: 7 years ago.
Category: Ford
Expert:  ttiger79 replied 7 years ago.
Hi!
Does the button on the inertia switch stay down? Is there any reason the inertia switch would have been triggered- was the truck in an accident?
Customer: replied 7 years ago.
Reply to ttiger79's Post: the switch stays down and there is no reason for it to have been activated, this has happened in the past maybe 3 times this last year and I turn the key off and then back on a couple of times and then the truck starts fine, although this time it has left me stranded
Expert:  ttiger79 replied 7 years ago.
If the inertia switch is down and there wasn't an impact, this isn't going to be your problem. Start by checking the fuel pump fuses and for a clicking sound from the relay under the hood. When trying to start the truck, you will hear a clicking from the relay if it is functioning. Let me know if the fuse is blown, too. There may be an explaination for this, too.
Customer: replied 7 years ago.
Reply to ttiger79's Post: I will go try that
is this a fuse in the engine compartment or is it by the break release and what size is it suppose to be ?
Thanks, XXXXX XXXXX to narrow things down I don't have a manual in front of me to tell me which fuse it is
Expert:  ttiger79 replied 7 years ago.
This will be under the hood. Check fuses numbered 1.2 (30amp) and number 1.1 (20amp) and number 2.30 (30 amp) All these fuses are in the fuel system.
Customer: replied 7 years ago.
Reply to ttiger79's Post: OK I have a 20amp fuel pump fuse @ position 10 thats good and a fuel pump relay @ position 301 don't hava way to check it at this point.
the motor is a triton 5.4 liter.
When I turn the key on I hear two faint clicks and what sounds like a vacume pump filling up and thats it.
Is there a way to check the fuel rail to see if it is pumped up? or am I going down the wrong path?
Thanks
Neil
Expert:  ttiger79 replied 7 years ago.
Sure. You are going exactly the right way. There is a test port on the fuel rail. You just have to unscrew the little plastic cap to access it. There is a test gauge to hook up here. The port has a schrader valve in it- kinda like a tire valve stem. If you press this valve in, you will release the pressure in the rail.

Do you have a test light or a multi-meter to test for voltage?
Customer: replied 7 years ago.
Reply to ttiger79's Post: well I think we are getting to the end of our rope. with the ignition on I depressed the shreader valve and there was no pressure and before that I squirted a good dose of starter fluid down the air cleaner after the filter and it acted like it wanted to fire but was only a jump in rpm and would not kick. you have been a great help so far and well worth the money spent
are you still game to help I can get a multimeter tonight
Neil
Expert:  ttiger79 replied 7 years ago.
Sure! Let me know when you get one! I'm sure we can find the problem. This is what I deal with every day!
Customer: replied 7 years ago.
Reply to ttiger79's Post: cool thanks
ok i've got the multi meter whats next?
Expert:  ttiger79 replied 7 years ago.
Ok!
Best place to start is the at the fuel pump relay. Remove the relay and turn the key to the on position. You will see two 12volt power signals and one ground signal at the base of the relay. The 12volt signals are positive signals from the fuses. I forgot to mention, check fuse number 1.18 (15amp fuse) under the hood. That is also one of the powers for the fuel pump. The ground signal is from the PCM- signals to turn the relay on.
The last pin goes to the inertia switch then to the pump. There will be no signal on this pin.

Let me know what you find!
ttiger79, Auto mechanic
Category: Ford
Satisfied Customers: 1257
Experience: ASE Master Certified, Advanced Level Engine Performance
ttiger79 and 12 other Ford Specialists are ready to help you
Customer: replied 7 years ago.
Reply to ttiger79's Post: ok here is what I found with the negitive lead grounded to the truck and the key turned on. I also replaced the fuel pump relay and it still does not start.

fuel pump relay position 301 four leads

             -- 11.5 volts
0 volts |
          |      -- 11.5 volts

             -- 0 volts

fuse position 10 fuel pump 20 amp fuse = 11.5 volts

fuse position 18 powertrain control/fuel pump relay 15amp fuse = 11.5 volts
Expert:  ttiger79 replied 7 years ago.
Excellent!
Switch the meter to OHMs and check for resistance on the two pins that you had no voltage on- make sure the key is on, too!
Customer: replied 7 years ago.
Reply to ttiger79's Post: ok with the key turned on
200k ohms was 5.9
20k ohms was 4.54
Expert:  ttiger79 replied 7 years ago.
Ok.
The next step would be to check the powers at the inertia switch. Probe the dark green wire with the yellow tracer and the pink wire with black tracer when the truck is being cranked over. Do you have voltage on both of these?
Customer: replied 7 years ago.
Reply to ttiger79's Post: ok last night I probed the inertia switch plug. one lead on one wire and the other lead on the second wire and got about 6V with the key in the on position. I will go probe it the way you suggest with one lead grounded to the body and see what current I get from each wire.
Expert:  ttiger79 replied 7 years ago.
Let me know what you find! Leave the connector plugged in when testing both wires.
Customer: replied 7 years ago.
Reply to ttiger79's Post: tried to get a good reading,I got 0 volts on both wires, don't think I was to succesful though. Battery is to low and stoped cranking. so where does this leave us, bad inertia switch or fuel pump?
Expert:  ttiger79 replied 7 years ago.
Nope. Something before the inertia switch. The dark green wire with yellow tracer comes right from the fuel pump relay. Try running a temporary fused jumper wire to this wire and see if the pump powers up. I bet it will.
If you are sure that you have two 12volt signals key on and a ground signal when cranking at the relay, you have a break in the power wire that leaves the relay- somewhere between the relay block and the inertia switch.
Customer: replied 7 years ago.
Reply to ttiger79's Post: well I'm sorry to say that I'm running out of time. I have to leave this Saturday for two weeks. You have been very helpfull and at least I know where the problem is. I have limited tools and time where I am at now and I am reluctantly going to have to call a tow truck :(
I will definately have to tell my friends about this site, it has at the very least given me some good knowledge.

Have a good one ttiger79
Neil
Expert:  ttiger79 replied 7 years ago.
Yeah. Electrical gremlins can be hard to hunt down sometimes. The one you are looking for would cause even some of the veteran technicians to pull their hair out!!

Good Luck and let me know if you need help in the future!!

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