93 f350 turbo, when I switched tanks on the way home, the fuel filter light went on. If I switch it back, it goes off. Btw, I was on the freeway. I also show a little bit of white smoke all the time! Recently had return lines, fuel filter, and injectors changed, runs good though. Any ideas? Thanks!

 

Sounds like your fuel selector valve is not switching. Only other thing I can think of is you possibly have a lift pump going bad. I went through 2 filters and kept blaming "gelled" fuel before I realized mine was bad. For the $25.00 I think I'd throw one on for the piece of mind. Just my .02

 

I would guess fuel lift pump or air being sucked in at the tank selector valve or fuel lines to the tank

 

Fuel filter light signifies a vacuum in the filter header...... when was the last filter change.


Take the filter header Schrader valve core out and hook a hose and pressure guage to the outlet.........crank engine see what you get for pressure, should have 4-6 psi from a good lift pump.

Volume test same place hook a hose to it crank over the engine 10 seconds you should get 1/3 pint of fuel minimum or 1 pint at 675 rpm in 30 seconds... engine running

Important the fuel shutoff solenoid (FSS) wire on the IP should be disconnected if you do not want a start just cranking. Re connect FSS after test complete.

 

filter was changed 2 weeks ago, gonna check the lines from tanks and selector switch this weekend, maybe change the lift pump?I have a vacuum pump, if it works, I'll try and test the filter. Thanks guys, I'll keep you posted!