When to “fully” bleed/vent fuel lines + crank no-start

[rreegg]

Hey all, have a question about when and under what conditions to “fully” bleed the fuel lines.

The engine is a Volvo marine 2 cyl diesel, MD6B. Dealing with a crank but no start issue after not running the engine for about 6 months.

I’ve cracked open the fuel lines at both injectors and get fuel when cranking - is this sufficient to determine the fuel lines do not need to be bled?

Have the engine manual and there is further bleeding procedure mentioned but not sure if it’s relevant since the injectors are getting at least some fuel.

asking because the “full” bleeding procedure is somewhat involved, needing a hand pump (which I don’t have), and the vent screw on the fuel filter housing is pretty buggered up.

Haven’t had issues with this engine before and have replaced the fuel filter and removed the injectors previously without needing to do extensive fuel line bleeding - it would start by cranking.

Any advice or tips are appreciated. My next steps are to look for leaks/air intrusion on the fuel supply/return lines and try to do more bleeding.

 

[ut99dot1]

hi, once you get it running it should bleed it self automatically. You might need to do a lot of cranking to get the fuel where it's supposed to be, because the starter got to work the injection pump AND the compression. I always use an electrical lift pump, makes the entire procedure alot easier. Check if glowplugs work, should make things easier.

Also run a clear fuel line to the injection pump, so you can see if there's bubbles going in

 

[rreegg]

Think the issue has to do with either old batteries or a starter that's going out. Haven't had the time to swap out the batteries yet but the cranks have gotten really slow - not much to indicate there's fuel delivery problems at this point

 

[DaveBen]

The engine needs to crank at 500 rpm or more before it will start. Batteries are the number one cause of no start.

 

[rreegg]

Got a new starter and that's cured the low crank issue. Back to square 1 in some ways and can't get the engine to stay running. After like 5 seconds of cranking it'll start to fire, and have gotten it to run for maybe 5 seconds but it always dies.

Cleaned out the air filter with diesel as mentioned in the shop manual.

Really seems like a fuel starvation issue and am revisiting the bleeding procedure along with other things.

I cleaned out the fuel tank by hand and replaced the fuel over this past summer, so things there should be good. Maybe the fuel intake pipe is clogged so will check that.

Whenver I crack the injectors some fuel comes out. When the engine does run for a small duration it does not seem responsive to the throttle - like it won't rev up only chug.

The fuel filter was also replaced last year with not a lot of time put on it - so that's another possible thing, along with the "fine" filter that's in the fuel pump.

I'm getting lots of white smoke out the exhaust during these false-starts so seem to be getting fuel.

Could this be anything other than fuel starvation at this point?

 

[Jesus Freak]

I'm just guessing, but maybe injectiors stuck open? Low compression? IP bad? Try an ATF soak in the IP as best you can.