Brief history: 89 4.9l 129000 .truck sat in va. for approx. 6years b4 i got it from my inllaws .gave it a tune up, and fuel filter. always used the front because the rear always showed empty and had the smell of very old gas. truck has always ran like a champ. Come to find out the rear tank was full the whole time. decided to run it out, swithed the tank and several times ive added gas to the rear to freshen it up. Heres the problem, Yesterday I ran the tank empty and it shut off.
switched to the front tnak and it would not pickup from the front tank. Towed it home chaned out the fuel filter and it still wont start. I looked the gas in the fitler and it was full of clay fines (dust i guess). When it first shutoff it acted like it wanted to start but was starved for gas, now with the new filter it acts like its notgetting any gas. Anythingi should be looking at? Iamwanting to remove the fuel line on top and blow air back through the filter and into the tank to maybe clear the lines, anyone ever do this ? is it ok or will i damage something?

 

Your truck has three fuel pumps, one in each tank and one on the frame rail behind the filter. Make sure the frame pump is coming on.

 

do you think that it would be okay to blow out fuel lines from the filter back?
looked underneath and seen the horizontal cylinder that is diectly behind the filter and also noticed a vertical cylinder behind it .

 

ok pump behind filter is working

 

check your pickup pump in your tank. have you tried filling the rear tank to see if it would start again? if not, you've probably got bigger problems than i hope.. hope that's all it is! need more help, you can email my at SVOmustangkidd@gmail.com since i'm hardly ever on here.

 

Front to back is the filter, frame pump, and DFR (dual function reservoir). I would not recommend blowing through the lines as the DFR has a valve that switches the tank the fuel is returned to. The reservoir on the DFR unscrews like an oil filter, and it fills with gas supplied from the tank pump that is selected. See if the reservoir is filling with gas. Fill it with gas and screw it back on to see if it will start.

 

ok thanx ford tough and sean for your help. switched the tanks back to the rear, placed 5 gal. in it, and it started. switched it back to the front tank and it is still running. must of had some air in the system and wouldnt pick up the fuel.

OOOPPPPSSSS!!!! spoke too soon front tank stalled again switched to the rear and it started again.

 

So this is telling me A: the tank pump is shot on the front or B: the lines from the front tank feed are plugged or shot. Am I thinking about this right?

 

The front tank pump is most likely shot.

 

thank you for your help