i have a lot of white smoke coming from my fuel return line, along with some fuel. i had been noticing this coming from the tank i was running on and the other day when i was using the fuel return lines to drain some fuel into a bucket. is there supposed to be smoke coming out? it seems like vaporized or misted diesel but its still weird

 

Never thought to look really, BUT if there is a bad injector which is leaking compression into the return line that could be part of the problem. Can you find/isolate a very hot injector......The excess fuel going thru the injector is to cool and lubricate it before returning to the tank. Are there any other symptoms........

 

I have seen this in the tank on cooler days, the hot fuel from the return line causes a "fog" to form in the tank. That fog will burn because it is fuel vapor.

I have never seen it come out of the return line with the fuel, I think PLC7.3 is right on with the injector leaking compression into the return lines to cause that.

 

a hot injector? all the injectors get hot and the fuel lines going to them get hot when the truck is up to temp as well.

 

ok well i burned my finger finding out what you meant. everythign got a little warm and the $5 and #7 injectors were REAL hot. the injector being bad and letting gas back threw it would explain the white smoke and the amount of air coming out of the return line. when i was getting fuel from the return line originally after i got some fuel in the bucket i put the hose into the fuel and got a lot of bubling. and so while i was checking the injectors lines and everythign i heard an odd squeky noise from the front fuel tank (the one i was running off of) put my ear up to it and it sounds line...bubles in a big metal tank hooray. i switched to the rear tank and listened there and got the same thing. so at least i know my switch valve is in good shape. and in a few days two new injectors.
also would the bubling in the tank get sucked up into the fuel pick up line? i am still having issues with it dieing and despite putting new line in everywhere and its all new tight shiny and clean i still see some bubbles ocasionally in the line going to the water/fuel seperator. the lines were leaky and it only dies under load or tryign to go fast like the freeway.

 

ok i swaped out the two injectors and the truck runs much better and a lot more power to it. also no more bubbles in the tanks all seems to work fine

 

If you still have the original water separator then you should be plugging the drain hose with a bolt and clamp after draining. The drain has a tendancy not to seal completely and allows air into the system and fuel drain off. Check the fuel pressure from the lift pump.

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.

 

i'll see about he water fuel seperator. i put a new lift pump in as it was cheaper than a pressure tester