fuel pump diagnosis help UPDATE!!!

[Todd Z]

Ok. So 2 days ago after over night the 2003 would not start. She cranked but nothing. I sprayed gas in the intake and she fired. I had to take blue to work. I checked the fuel pump fuse and switched the relay. Nothing. So after I got home it fired right up!!!

I drove the truck about 30 miles. Then the next day I went out as I was pulling in a friends driveway it stumbled and died. Same as before. Cranked. Turned the key on and off fast a few times and it re started. I left it for 3 hours and drove it home. Let it run for over and hour and nothing it stayed running. BUT the fuel pump relay was seriusly hot. To where it burned my fingers.



So I am guessing the fuel pump is shot????

Thanks in advance.

Todd Z

 

[scott degroot]

There is only one way to make sure that is 100% the fuel pump. You have to check for voltage at the fuel pump, voltage drop test on the fuel pump ground while monitoring fuel pump pressure while trying to start it. If the voltage at the fuel pump is above 10 volts while cranking, the voltage drop on the fuel pump ground is less than .5 volts while cranking and there is no fuel pressure then you have a bad fuel pump.



Your symptons do sound like you have a fuel pump issue though.

 

[EddieS'04]

Todd, also your symtoms sound simular to some members that had a bad reset switch.

 

[Vic Sorlie]

How long since last fuel filter change? You prob stay on top of those, but getting a bad load of gas at the station ain't out of the question.

 

[Vic Sorlie]

How long since last fuel filter change? You prob stay on top of those, but getting a bad load of gas at the station ain't out of the question.

 

[Norm Reeves]

Crankshaft sensor.......:grin:

 

[Todd Z]

I hope it's the pump. The pump runs at times and at others it doesent. It's out and going to be changed. The old school spray fuel in the intake and it started I hope helps confirms it. That relay was crazy hot. Of course today it drew a lousy 5 amps when I was using it to empty the tank. I did not check voltages at the pump. I hate doing things this way. Not me.



Fuel filter was changed last summer.



Crank shaft sesor? Would it cut out the injectors? This when I sprayed fuel in the intake or did the key jerk it started?



Todd Z

 

[Norm Reeves]

My source...could be wrong

 

[scott degroot]

Here is a little know tip about Fords and crankshaft sensors.



When you turn on the ignition all of the dash lights illuminate to do a bulb check..to include the check engine light. If the pcm is receiving a crankshaft position sensor signal during cranking the check engien light will go out.

 

[Vic Sorlie]

Nice info l1tech - the tidbits you give are invaluable!

 

[Todd Z]

L1 That is great... Thank you.

USN, The truck runs great when running, no hesitation, Nothing. I am rolling the dice here i guess...



This sucks.



Todd Z

 

[Todd Z]

Update. Inertia switch connector is melted to hell and the switch is cooked. So looks like the pump failed drawing too many amps or the ford crap wiring strikes again!!!!!



Todd Z.

 

[Mark Price 2]

Sounds like you nailed it! Good job.



Video:Spec Topix 1 War Story Where There is Smoke - 21 min.



This is a great case study from Mr. McCuistain. He is an instructor and regular contributor to Motor Age Magazine.

'88 Ranger - Failed fuel pump drawing too many amps and frying inertia switch among other things. Also, involving a new alternator. Hmmm. Very interesting stuff! Also teaches why it's not a good idea to only check your charging system with a volt-meter.

 

[Mark Price 2]

My connector on the inertia switch half way melted years ago but was still operational. I replaced the switch and no issues since. The connector is still melted but operational. Still have no clue as to why it did it.