fuel filter light - Diesel Forum

bcgeorge · 01-14-2007, 04:34 AM

Last weekend I was down at Mom’s in Seward, started home Saturday night, the temp. was around zero there then dropped to around -20F as I climbed into the mountains, after about 30 minutes the Fuel Filter light came on and truck died. Was able to restart it and milk it back about 2 miles to semblance of civilization after many stalls & restarts, then towed it all the way back to Seward (30miles) . Thought my fuel was just jelling, so let it sit overnight then went and bought a gallon of power service, and split that between the two tanks, and replaced the fuel filter, still wouldn’t run for more than a couple of minutes and filter light almost constantly on. Temp still around zero during the day. Finally left it for the week then went back down Friday and started it, wasn’t to happy but it did start (temp back up to 30-35 during the day 20-25 at night) I then drove it 120 miles without fail till about 5 miles from home, the fuel filter light came back on again, but this time no sputtering till I backed into the driveway then it died. Drained a bit from the fuel filter, no water as I was starting to suspect, took it to the grocery store (couple of miles) and back no problems, no filter light.
What could be causing this?????

cdnsarguy · 01-14-2007, 10:10 AM

Fuel lift pump.........

There are only a couple things that would cause a VACUUM in the filter header and activate the "Plugged Filter light" bad lift pump, blocked dirty filter, gelled fuel. A good IP can draw fuel in and run causing it to set of the light too.

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.