I changed my fuel filter and loosened the bleed screw on top of the filter. I operate the manual pump priming lever on the fuel pump but I feel no resistance. I rotated the crankshaft clockwise (several times) and pressed the lever after each turn but still no resistance. I removed the fuel filter and confirmed that no fuel was being pushed out by the priming lever. I don't have anyone on board to help with the process so I haven't tried cranking the engine to bleed the lines that way. Any advice?
Problems Bleeding Fuel Lines in Yanmar 3GM30F
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I did not change the o-ring but cleaned and was in good condition.
If I am sucking air when this screw is open, where should I start bleeding the line?
The problem that I am seeing is that the manual pump lever is not pumping any fuel through the line. Could this mean that there is a leak before the fuel pump? I have never had any fuel in my bilge.
If I am sucking air when this screw is open, where should I start bleeding the line?
The problem that I am seeing is that the manual pump lever is not pumping any fuel through the line. Could this mean that there is a leak before the fuel pump? I have never had any fuel in my bilge.
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Probability is air leak. That you changed the filter without changing the Oring also promotes this as an air leak potential .... the newer blend of diesel fuel cause the normal neoprene/BUNA rubbers used on 'filters' to swell and change dimension.
Rx: disconnect the filter O-ring and carefully visualize that the o ring has not swollen and no longer perfectly fits into into its O-ring groove, etc. Be sure to 'lubricate' the o-ring with diesel oil when reinstalling which will help prevent 'pinching' the o-ring during tightening of the closure. Always change out the 0-ring for new when changing or reinstalling fuel filters.
Best is to obtain Viton® O-rings and keep them as spares; viton® compound rubber is more compatible with the newer diesel fuel blends .... especially diesel blends that have been contaminated with so-called (reclaimed) bio-fuels mixtures.
Rx: disconnect the filter O-ring and carefully visualize that the o ring has not swollen and no longer perfectly fits into into its O-ring groove, etc. Be sure to 'lubricate' the o-ring with diesel oil when reinstalling which will help prevent 'pinching' the o-ring during tightening of the closure. Always change out the 0-ring for new when changing or reinstalling fuel filters.
Best is to obtain Viton® O-rings and keep them as spares; viton® compound rubber is more compatible with the newer diesel fuel blends .... especially diesel blends that have been contaminated with so-called (reclaimed) bio-fuels mixtures.
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The Racor primary is before the priming pump on the engine. When you replace the primary filter, you need to it with clean fuel and minimize the amount of air inside when you put it back together. There is very little resistance to pushing the priming pump, so its hard to tell if you are really doing anything. Best way is to crack the bleed bolt on the engine filter and see if fuel and/or air comes out as you pump.
If your fuel system is now filled with air, I would try the following. Engage the decompression levers, close the cooling water thru hull, pull the engine stop, and then spin the engine using the starter. Hopefully that will pull fuel through the system and return any air back to the tank. If you just try to start the engine and air is the system, you will get air into the high pressure injector lines and starting will be a problem.
If your fuel system is now filled with air, I would try the following. Engage the decompression levers, close the cooling water thru hull, pull the engine stop, and then spin the engine using the starter. Hopefully that will pull fuel through the system and return any air back to the tank. If you just try to start the engine and air is the system, you will get air into the high pressure injector lines and starting will be a problem.
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Or crack an injector open, turn over the motor and get the air out between the engine mounted fuel filter and the injectors.
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It takes an incredibly long time to get fuel through the system with that ineffective little pump arm on the fuel pump. It could be that you are just not pumping long enough to fill the filter bowl. To me it is a design flaw that it is so darned difficult to redistribute fuel on these engines (I have a 3GM30F in my boat). For example, I have a little 30 hp Kubota diesel in a Bobcat which has a very convenient outboard tank type squeegee to get fuel flowing if she runs out of fuel. It's a quick procedure to get the thing running again. I have one of those handy for the next time the Yanmar needs priming and will try to install it permanently.
Another issue with the Yanmar is the well disguised second, injector pump bleeder screw that sits behind the heat exchanger hose. If you don't know about that, it can cause a lot of frustration in trying to bleed the system.
Another issue with the Yanmar is the well disguised second, injector pump bleeder screw that sits behind the heat exchanger hose. If you don't know about that, it can cause a lot of frustration in trying to bleed the system.
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