Ford1990

Good evening everyone. I have a 1990 F150 4.9 with dual tanks. I drove her to work last week and when I went to leave for the day she wouldn't start. No problems leading up to this...It seems like a fuel problem. We replaced both fuel pumps, the fuel filter, the fuel pump relay, and checked the inertia (fuel shut off) switch. I also can't hear the fuel pumps when I turn the key.
I'm not sure what I should try next and don't have the money to keep buying parts that won't fix the problem. I would rather not tow it to the mechanics in my area, I've never had a good experience with any of them. I would greatly appreciate any feedback or advice.

broncojunkie

Will it try to run with a little starting fluid sprayed into the intake? Have you pulled codes?

Nitehawkjr

Have you checked the voltage going to the pump relay? If not I would start at the fuse link by the starter relay it will be labeled W and I believe it’s yellow then proceed checking the circuit from there toward the pumps.

5Rangers

That fuel tank selector switch there is notorious for dropping volts. Just because you hear the pumps run, doesnt mean they are getting everything they need, for example, my pumps were getting about 7vdc at the connector. Not enough to allow it to do its job.

Ford1990

I just pulled the codes KOEO--it gave me 21, 26, 24, and 95. According to my code reader book, these are the results:
21 is Cooling Temperature sensor out of specified range
26 is MAF sensor or circuit fault, transmission temperature sensor fault
24 is intake air charge temperature or VAT sensor out of range
95 is fuel pump secondary circuit fault.

I haven't tried using starting fluid just because I'm scared that I'll break something else...I know a lot of people use it but I'd rather not just to be safe.

Ford1990

Thank you! I'm going to try to replace that tomorrow and see if I have any luck

Ford1990

Hi all. I just replaced the fuel tank selector switch--took me awhile to find one. The good news is that the truck tries to start now and turns over. The bad news is that it dies shortly after and gas is now leaking from somewhere as soon as the pump turns on. I tried both tanks and it did that for both. Any advice is appreciated

5Rangers

Find the gas leak..

Singlecab

I hope y'all keep going with this! I'm having the same problem. I think. Truck won't start now and the fuel pump,relay keeps clicking.have to disconnect battery so it doesn't run down.it all started, i think after I wash the motor at the car wash. Not sure what to look at first. Why would the relay keep making noise when truck is turned off. Thanks for any help. Tom

5Rangers

Pull the relay. Get some electrical cleaner and clean the sockets. Pull the support the relay socket is mounted to and check the back side, pull the wires gently and make sure they stay in. Pull the connector off your computer, clean both sides male/female real good with a short bristle brush and the electrical cleaner and reconnect. Disconnect the negative battery post before doing all this.