Blown apart injector return line..again.

lmorris · August 22, 2016

Another dealership replaced the injector return line because it blew apart, now it's here for the same concern after having 250 km put on it. I seem to recall someone else having this issue before due to a restriction in the fuel system somewhere, but I can't find the post. Might have been on the Ford message boards, not sure. Anyone remember anything about this?

A faulty injector with an internal leak causing excessive pressure to the return line seems to ring a bell now. Question is determining which injector.

Matt Saunoras · August 22, 2016

DEF in the fuel can clog the return line causing it to blow apart

kridd12 · August 23, 2016

Have seen a few of those situations, all have led to complete fuel systems from some sort of contamination either def or metal.

mchan68 · August 23, 2016

If it's an F-550, how's the condition of the tank?

lmorris · August 26, 2016

No contamination of the high pressure system, but the fuel drained from the separator was nasty. It's an F350.

Keith Browning · September 3, 2016

DEF in the fuel can clog the return line causing it to blow apart

Is there an explanation for this? I have heard this a couple of times and I think this idea has been propagated on the FMC boards. If the concept is that the DEF is crystalizing and clogging the lines then we need to be reminded that DEF will not crystalize without air. Liquid DEF in the fuel will never do that directly. I also believe that if there is DEF contamination that causes rust, pitting and metal flaking far worse things are likely to become evident before a return line failure, especially repeated failures on a single truck over time - BUT - I would subscribe to the excessive pressure theory which could be the result of DEF contamination.

Just thinking out loud here.

Matt Saunoras · September 4, 2016

I did have it happen to me. Confirmed DEF in the fuel, customer wanted me to try replacing the filters first and I did so. I got about 3 miles away from the shop on the road test and the return line blew apart at the number 3 injector. Perhaps the DEF reacts with and swells the rubber fuel line. The truck ran totally fine until that point.

lmorris · September 6, 2016

I found nothing wrong with the system, other than the water in the separator. I put the line back together and so far there has been no issues. I wonder now if the tech took the line apart at that point for ease of installation and never got it back on all the way.

lmorris · October 27, 2016

Well it's back, blown off the fitting for one of the injectors now. The customer is none to happy. Pulled a sample of fuel and the diesel is cloudy. Again we tell him he needs to flush his tank. Got the service manager on my side with this one, no warranty repairs for this one, and we don't touch it till he lets us clean out his tank.

wewille · March 10, 2017

Do you have an update on this one?

lmorris · March 13, 2017

Ya..forgot about this one. Another tech cleaned out the tank and flushed the lines, and replaced the filters. New return line is still staying together as far as I know.

cbriggs · March 15, 2017

It is right in the fuel contamination job aid, about def clogging a fitting and blowing the return line apart. Your fuel sample looks exactly like the one I got out of a truck a few weeks ago that put 8L of def in his fuel tank. The def seems to react with the fuel and turn the watery part all brown, and then turn all the fuel cloudy like lemonade almost. My customer declined fuel system repairs, just wanted the tank cleaned, filters changed and the LP system flushed. Not sure if its still running, he was from out of town. It was a 2016 with 45k on it. We did submit a warranty change request.

lmorris · March 15, 2017

Crazy thing is that I took apart everything that the GSB lists for contamination checks and not a single sign of DEF anywhere. Now we know. Thanks for all the input guys.