Yanmar 2GM20F cranks but no start

[Justin_NSA]

Argh! In my last episode, I had to pull my boat out to replace the broken starter and chewed up flywheel ring. The prop shaft and transmission had to be pulled back, but pretty straightforward albeit not cheap. So yesterday we put the boat back in the water. Well the engines cranks just fine now, but it won't start!
Decompression valve is closed. I suspect a fuel problem even though the fuel system has not been touched during other maintenance. Tried bleeding it, no effect. Lift pump priming lever doesn't feel right. I assume the first fuel filter on the tank side of the pump, not the filter on the engine, might be clogged. I disconnect the fuel line on the output side of the filter and it is dry. I expected fuel to pour out. I replace the filter in the bowl and try to start it again. It starts, but dies after about a minute. Line is empty again.
Plenty of fuel in the tank. Could it be an obstruction in the line from the tank to the first filter? I thought about using my MightyVac to see if it's possible to pull fuel thru the filter on the output side. Is it possible that the lift pump is bad and needs to be rebuilt? Maybe I just haven't worked the pump lever enough to draw thru the filter. Any thoughts?

I've done a "boatload" of work this off-season and I want to go sailing!
New ProCharge charging system
LasDrop GenII dripless shaft seal and split coupling
Centering clamp in Hood Furling drum
Starter and flywheel ring

 

[Charles Erwin]

The lift pump arm (inside the motor block) moves up and down on a cam lobe. The cam moves half a rotation for every crankshaft rotation -- so if no throw on the lever move the crankshaft clockwise one turn (by hand compression released) or until you can push the lever down. You will feel resistance as the lever engages the pump spring. Push it all the way to the spring resistance and then further til the lever stops - then release. If no joy then ----

Physically check the tubes/lines on the suction side of the lift pump. Go from the lift pump back to the main filter then back to the tank including the bitter end of the pickup (dip tube) in the tank. The main canister needs a new element and the O rings must not be pinched or nicked. Consider the rubber feed tubing itself. You may have an internal collapse. Consider replacing the suction side with brand new fuel line from the auto supply. Also double check the hose clamps along the way.

When all is done disconnect the pressure side of the lift pump, pump the lift pump lever, until you have good fuel flow. Use a catch pan to keep things neat. Reconnect the pressure side and bleed that side by levering and using the bleed screw on the top of the engine mounted filter canister until the canister is full - no bubbles - paper towel here to catch out flow from the bleed screw. If this is a Yanmar use the smaller bleed screw on canister top (the larger one is notorious for threads getting stripped - fixable for cheap but a real nuisance.)

If that does not do the trick then come back.

Charles

 

[kloudie1]

Yeah.. one of the banjo connectors may have been jostled loose during work.. sounds like an air leak.. Do the fuel pump bleed as Charles noted; put a wrench on all the banjos and just make sure they are tight (carefully, without stripping the little dears)

 

[Justin_NSA]

Thanks for the tips. I checked everything. It turned out to be a cracked rubber fuel line just before the Racor filter. Whoever originally installed the filter mounted it too close to another bulkhead, so they made a hard right angle bend in the line to go around the wall. I drilled a hole in the plywood wall and fed the hose thru. No bends.