Fuel filter light on - and engine running very rough - stalling

[dkrahn]

92 F450 7.3 broke down on my on the freeway the other day. Had it towed back and didn’t know what was wrong with it – seemed like a fuel problem, sputtering bogging down and finally failing. When I got it back – I changed the fuel filter – no luck. Took it to the Ford dealer – they said it was the switch that tells the system which tank to pull fuel from, basically sucking off one tank until it was dry even though the current tank selection showed ¾ full; basically ran out of fuel. I picked it up from Ford today brought it home (about 15 miles drive – everything was fine). After I got back, I fueled up both tanks and drove less than ½ mile when ‘fuel filter’ light comes on. Engine now starts to sputter and it stalls on me. I am able to limp back home after stalling several times. It starts and idles now (rough) but if I get on the accelerator at all – starts to smoke – sputters and dies. I thought might be bad filter? So I tried to put the old one back in – same thing ‘fuel filter’ light still on. What is going on? Thanks.

[OkieGringo]

Well, assuming(I know it's not good to do so) that the Ford Stealership replaced the tank selector valve, and that the filter isn't plugged, my next W.A.G. would be lift pump going/gone south(ie. bad), thus starving the engine. [img]/ubbthreads/images/graemlins/shrug.gif[/img]OkieGringo

[cdnsarguy]

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when cranking. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of engine cranking, route fuel to a suitable container with a hose.

If there is a problem with the lift pump and you are changing it, ensure the new pump comes with instructions as to correct installation procedure if it is the newer model pump with the almost straight arm.

Gotta love Ford dealers/techs pick.... the most expensive thing to change with same results........ [img]/ubbthreads/images/graemlins/rolleyes.gif[/img]

[dkrahn]

Well, changed the fuel pump – same thing!!! Maybe I got some bad fuel for whatever reason at the 76 station? Drained all fuel in one of the tanks and replaced it with fuel from another truck; same thing!!! Help me guys!!! If there is a line that is sucking air how can I find that? What other problems could this be???

[cdnsarguy]

Dennis the light signifies there is a vacuum in the filter header.... where there should be a 4-6 PSI pressure......

Check the fuel for gasoline.....you would not be the first to get a bowser driver dumping gas in the diesel tank at the station.. always get a reciept even for cash.

Do a pressure and flow test of the fuel pump at the Schrader valve on the filter header (FSS- fuel shutoff solenoid disconnected on IP). Remove the tire valve core and hook a hose and pressure guage on it should see 4-6 psi when cranking. Then do a fuel quantity test same place, should see 1/3 pint in 10 seconds of engine cranking, route fuel to a suitable container with a hose.

One other thing does the fuel guage switch on the dash when FSV (tank)switched. Do you hear a ziip from the FSV when tanks changed.

visit....... http://www.intellidog.com/dieselmann/idi.htm read all about the fuel system.

[dkrahn]

I will check the pressure and flow, even though I just replaced the pump yesterday. Another thing, when I drained the tank yesterday, it didn’t show any change on the fuel gauge on the dash? Both tanks were full, I drained the rear tank – but it continued to show that it was full, I switched back and forth between the two tanks but the needle wouldn’t move – just showed full? Could this be a symptom to my problem? What the hell is going on here??? I am losing my mind!!!

I can’t hear any zip from the valve – but I have never heard it before either.

[cdnsarguy]

Have you check all the fuses in cab and engine bay fuse box...

How about the tank switch on the dash.........