This questions is regarding my '89 F150 ext cab 300 I6 5speed dual fueltanks. She was parked outside for one year. I tried to start her up 2 weeks ago and dicovered a wiring problem. The problem has been solved now (I had a loose ground connection at the starter motor).
Now she is cranking but doesn't want to start. I checked the inertia switch which seems to work fine. I checked the fuelpump relais (I hope I got the right one since the cover is gone) and it seems to work too. If I am not mistaken this is the green colored relais by the airbox. The relais is clicking when the ignition is turned on. I checked voltage at the fuelpump under the cabin and don't get any reading and no humming noise hapening. Is there a way of testing the fuelpump (maybe hocking up 12 volt to it)? When I switch between the tanks I get different fuel amount readings which seems to be right as far as I remember. Both tanks are leaking at the top, the rear tank has not been used in years. The front tank only gets half a fill at then most. I now this is a safety issue but the truck gets very little use (less than 500km a year, Only to haul stuff to the dump).
So what is the next thing for me to do at this stage.
Any help is appreciated.
Thanks Martin

 

Check the fuel filters, probable two, one located in the black round container on the driver side frame rail, where the two lines for each fuel tank meet. The other is located about 3 to 4 feet forward on the same frame rail. The black round container has a spin off cap at the base and the filter is inside.

 

Fuel pump is not working, the pump relais is switching when the ignition is turned on.

 

Check the fuses in the cab, Check the battery cables for any broken or loose connections, Check the wires at the starter solenoid. Will need to check for battery voltage at the fuel tank with a voltage meter, The fuel pump only kick on for about 2 to 3 seconds and will shut down when the key is turned to the on position. There should be a check valve which looks like a tire valve which mounts to the fuel rails on the intake, and can also be used to check for fuel..

 

Have you checked power at the inertia switch? It may look fine, but still not pass current. Also, just because the relay is clicking doesn't mean it's working either.

 

Here again, just because it clicks does not mean that it is passing current to the pump. Check the output terminal with a test light to be sure.

 

So, I took the relais out and hocked up 12 volt to it and had the relais switching (I opened the housing and could see it) . On the 2 other relais teminals I hooked up a DMM and had current flowing when the relais switched on. I installed the relais in the vehicle and it works the same way there. Then I checked the fuel pump under the cab. When the ignition is turned off I have current flowing on the harness plug. When I turn the Ignition on the current changes. Then I hooked up the fuel pump again and had somebody turn the key for me. When the ignition is turned on for a short time I can feel very little humming on the pump. Is this normal. Maybe the pump is stuck and doesnt turn, I don't know. I can't hear any humming noise on the pump. How do you check if the pump is actually pumping fuel?

 

Two ways of checking if the fuel pump is pumping fuel. With a fuel pressure guage hooked to the fuel rail check valve on engine or disconnect the fuel line and run the fuel line into a container (empty coca cola bottle works fine) and turn the key on. Be careful when working with fuel.
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Buck