Bleeding air from fuel system

[abcnuzeman]

For days now, the Yanmar 1GM on my CD 25D has been sluggish, only reaching about 2100 RPM. After about 20 minutes of motoring, it would finally start running better, reaching 2800 RPM and apparently running smoothly. My initial thought was a dirty filter, so today I replaced it. Now I can't seem to bleed the air out of the line. My manual indicates that the bleed screw should be loosened on the filter housing and the priming lever of the fuel pump exercised until diesel leaks out. I pumped that lever for over 30 minutes with no results and of course, the engine won't start at all. Am I not doing something right? Is my fuel pump the real culprit and should it be replaced? There is also a long thin canister between the tank and the fuel pump which I assume might be another filter, but I don't know how to check or clean it. As you may gather, I'm really new at this diesel stuff, so any help would be appreciated.
David Owens

[Trawler Joe]

Hi David,
Not sure if this will be helpful, but the first time I tried to bleed the fuel lines, I had the same experience as you. Turned out I was just not pushing the lever through the whole range, so I wasn't pumping anything at all... I have to push the lever down harder than I realized; don't just wiggle it up and down within the range of play, make sure you push it firmly down. My makes an audible suck noise, and I immediately see bubbles coming out of the filter screw.

-Joe

[J D]

Had the same problem. I had not pushed the fuel lever to max. I later added a priming bulb between the fuel tank and filter now a few squeezes and its bled.

[Trawler Joe]

Also, if you're doing it right, it won't take long. Mine takes 5 minutes max, probably more like 2 minutes, and it's a bigger engine.

[rollo_cd26]

Although not the same engine, my Westerbeke 10two suffered from a fuel injector pump not delivering fuel at pressure to the injectors. Same symptoms as yours, no start after many repeated bleed attempts. A fuel injector service freed up the fuel rack that controls the unit, cleaned it and tested it. The long cylindical thing between the tank and the filter is a separator to remove water and particles from the fuel. It should have a drain plug on the bottom to empty it. It all gets down to clean fuel injected into highly compressed air at the correct moment. Besides this web site, a good source of trouble shooting and repair knowledge is "Maine Diesel Engines" by Nigel Calder.

[Jim Davis]

JD is right on how handy they can be. Also consider a low pressure 12 volt fuel pump that allows flow through. One word of caution, my favorite diesel shop suggested I change the bulb every two or three years as they deteriorate some when used with diesel.