PDQ OWNERS FORUM

looking for some guidance in the bleeding process after changing fuel filters. It seems there may possibly be air in the lines after filter change in the yanmar 100hp

thanks again,
kip

Kip, what you are assuming is true. Here’s the procedure I follow when changing both fuel filters annually. It has worked for me every time. (Meaning nor air in the system)

CHANGE FUEL FILTERS
1. Have 1 pt of diesel fuel (to fill new fuel filters)
2. Turn fuel valves on main fuel tank OFF before changing fuel filters (under floor board at entry).
3. Change Raycor fuel filter & gasket first... change big gasket & small O-ring; fill holder w/ diesel fuel (leave ¼” space).
4. Change small fuel filter on engine (no gasket) - fill with diesel fuel
5. Turn both fuel valves on main fuel tank ON and open purge valve slowly.
6. Pump air out of fuel filter on engine. BE SURE TO RE-TIGHTEN AIR PURGE VALVE!

I also suggest you read the Yanmar maintenance manual on this topic.

thanks Mac. that is a awesome guideline and I am sure will be helpful to a lot of people....I sorta figured it out on my own but your way seems way easier. I would advise people to write this down because you never know when you may have to change filters on the go.....I like most everyone carry extras just in case.
thanks again
kip

I agree, Kip. I record a lot of routine and annual maintenance actions like this in my "Notes" app so they are accessible any time, any where on my Apple computer, iPhone or iPad.

my update to my fuel filter problems and some advice to others who may or may not check this area when changing filters. I had a fuel restriction problem. My first thought was to change the filters and hoped that solved the problem while I was underway. As my copilot was running us home on one motor I set on changing the filters on the star motor. I was able to accomplish this but found the restriction was still there. What I failed to do until we got home was check both fuel lines into the racor. After doing so I found the restriction and the problem clogging up the upper valve. Just a reminder to everyone that does their own filter changes to check both feeds to the fuel filter before priming to make sure you have no build up in that area like I did. It turned out not to be a costly problem but a real pain in the ass for sure

Lyons Pride

Interesting. Could clarify how you found and fixed the clog in the fuel line to the Racor filter.

thinking I soloved the filter problem by changing them I still had the restriction and thought maybe it could be in the fuel injectors or motor so I tried to eliminate the motor as a possible problem all together.. I simply used a 2.5 gallon can of diesel and routed the fuel feed into the racor into that can bypassing the the racor all together. while pulling fuel into the motor from the can the motor ran great without restriction thus showed me the restriction was not being caused by the motor. At that time I inspected all fuel lines in the racor and found the partial obstruction. usually people don't take the fuel lines off the filter when changing them so now I am hoping this process helps others. I now feel that I should probably replace the whole fuel line altogether but would like some guidance from someone who has done that before because as you know that line goes under the floor board. I also now need to consider having the tank cleaned as well......I am not the smartest guy around but I have my moments
Oh i forgot mac that I used compressed air to clear the line going to the main tank. At this time the line is completely clear

Kip

Very helpful and interesting, Kip. Nice detective work.

As far as cleaning the fuel tanks, it’s a good idea... especially if you experience any kind of fuel issues. I paid for this service on both of our fuel tanks last Spring. As you may know, it is not something an average boater can do - it requires special fuel filtering equipment and someone skilled at doing this kind of dirty work.

They had to cut large holes (about 12”x14”) in the top of both of our tanks. The service included special, very secure hatch covers that can be used again to clean the tanks in the future. It also requires cutting horizontal holes in the vertical baffles inside each tank.

Some fuel tanks, they say, show a lot biological “gunk” layered on the bottom, especially in warmer climates. Our tanks were quite clean. They also took detailed pictures inside the tanks to show me areas of corrosion. It took half a day and was worth the money.