fuel filter return line problem?

[GREASE FIRE]

i recall reading somewhere on this forum that there is a return line on the fuel filter that can cause leaks and i am wondering if that could have something to do with the fact that my truck takes considerable amounts of cranking to start sometimes. I don't see any fuel leaking around it, but one thing i noticed that seems strange to me is that, when the truck is parked, and i push in the tire valve thing there is no fuel squirting out at all. Shouldn't there be at least some pressure in the filter even when shut down? My 6.2 van has the same fuel injection system and if i disconnect the line at the filter (i have hydraulic quick connects right there for purging) the fuel will squirt out under pressure for a moment. Could it be possible that fuel is bleeding out to the return line while it sits and allowing air into the line that goes to the pump?


i actually did a little test today - i had the fuel tank out to replace the sender and when i put it all back in i was using a 12v lift pump to prime the system right at the filter head, then once fuel came out i disconnected it and cranked for several seconds without glow plugs just to prime the system a little more - while cranking the truck was kind of shaking a little and showing no signs of starting. Then i gave a good 8 seconds of glow plugs and it fired immediately when i cranked it - much faster than any other time except when the engine is hot and shut down for a short time.

So is the idea that i should just plug the return line at the filter head or does it have to be set up like that?

thanks,
Paul

 

[Agnem]

The return line at the filter head facilitates a route for air to go - down to the tank, rather than into the IP. However, if you want to try it as an experiement, you can plug it. There would be no harm done. IF air does get upstream of the filter head though, you'll have a devil of a time priming it.

 

[jim_22]

Are you sure your filter is not clogged?

 

[cleithau]

I plugged mine when I had a problem with the return line o-rings leaking. Mine started better after that. I fixed the o-rings but never put the hose back to the filter, never had a problem with air in the lines, drove across the country a couple times. I'd say plug it, run it, if it starts better leave it plugged. It only take a couple minutes to hook the hose back up if plugging it doesn't help.

 

[subway]

i plugged mine with no ill effects. i did so because i only wanted one way for the return line to go for my added fuel relay but that is beside the point.