New fuel filter, working pump but truck wont start - Diesel Forum

centralmasslandscapes · 12-19-2009, 10:29 PM

Our 2007 f350 6.0 ran really rough this morning so we took a look at the fuel filters and they looked pretty bad. We replaced them and follow the directions provided with the filters and some from online. The truck started and ran for less than a minute, then it died and wont start again. I checked the secondary fuel filter/ bowl and the pump was sending a mix of fuel and air which would show that there is still air in the lines. Do we need to fill the primary filter with diesel? any ideas?

Thanks

redneck_rheino · 12-20-2009, 12:22 AM

I've never had to refill the bowl when changing. check your main filter down on the frame to make sure you tightened the cap and its not sucking air.

69cj · 12-20-2009, 10:01 AM

You could also have a damaged O ring on the primary filter. Did you coat it with oil and torque to spec? Did the cap bottom out. The O ring does the sealing not the threads.

donniejimmy · 12-20-2009, 01:06 PM

I had the very same problem the first time I changed the fuel filters on my 6.0 too, ran fine for about 1 minute, then died and would not start. Called my diesel mechanic and he said that was very common after a fuel filter change...air in fuel lines. My question to him was "Why isn't that even mentioned in the instructions on changing the filter!?" I was ready to have him come tow my truck back to his shop! He said the fix is rather simple: 1. Make sure the cap on the primary filter is tight and the o ring is doing its job of sealing...oil it AND the threads on the cap lightly. 2. Then, very slowly loosen the cap on the secondary fuel filter in the engine compartment until you hear the air in the lines rush out (I also had a small amount of fuel spew out, too). DO NOT take the secondary cap completely off...just loosen it to let the air out. Then tighten it again, cycle the key on and off a few times and it should start. Mine did run a little rough for a few minutes and then it smoothed itself out. Hope this helps...

centralmasslandscapes · 12-21-2009, 01:30 AM

I'm going to look things over tomorrow, the truck sat out this snow storm since we couldn't get the problem fixed last night. The cap had some trouble going back into the primary filter threads because of pieces of sand etc falling into the threads. I cleaned these up and it went in alot easier. What oil should i use on the o-ring? does the oil on the o-ring really make that much of a difference? I think i may be able to hear air hissing around the filter area when the key is turned but im not sure.

69cj · 12-21-2009, 10:22 AM

Any type motor oil or even vaseline. The object is to keep the O ring from pinching or binding till the cap bottoms out.

centralmasslandscapes · 12-22-2009, 07:00 PM

Hey guys,

Thanks for the advice, I went out today and pulled the filter back out and put Vaseline all over the threads and o-ring, then I turned the key to get the pump going and remembered to loosen the cap on the secondary filter. Fuel sprayed everywhere when I did that since i forgot to do that first, but atleast I knew everything was working again. The truck started right up after a quick battery charge and is running alot better with the new filters.