Bleeding air/fuel - 2QM15

[garylinger]

After having the boat for just over 1 year I have decided to replace the fuel filters. I have delayed this because of uncertainty about how to do it. After reading the Yanmar Owner's manual and the Yanmar Service manual and a visit to a local Yanmar repair facility/dealer, I am more confused than ever - there is conflicting information.

I have a fuel filter between the fuel tank and the engine mounted fuel strainer. I know that there is a bleed screw at the top of the fuel strainer and that I need to manually operate the fuel pump lever. My problem is not being able to determine where to go from there. Different references say different things about what to loosen to bleed the system. One place it says only to open the connection at the high pressure pump and another says to open each of the banjo fittings at the injectors. The person at the Yanmar dealership said there is a bleed screw on the high pressure pump (I can't find one) and I don't need to open any of the banjo fittings.

Can someone who is familar with doing this help me with the specific steps?

 

[Scott T-Bird]

You should be able to identify the bleed screws by the 10 mm head with the phillips head grooves (they are all the same). On my 1GM, it is located right where the fuel line is connected at the injection pump. My manual mentioned something about loosening the nut at the fuel line connection only one turn to only check for proper flow (but it doesn't sound like it should be necessary after bleeding for a fuel filter change). I had problems just a few days ago with power loss and I noticed that I had to pump the lever to get fuel squirting from the bleed screw at the injection pump. However, my problems disappeared when I noted that fuel flowed freely from that opening until I closed it. It didn't need any pumping to get fuel flow (as it does at the fuel filter). Also be sure to loosen the nut at the bottom of your primary filter to make sure fuel fills that canister as well.

 

[Ed Schenck]

Another option. My first year with my 2QM20 was fraught with dirty fuel and other engine issues. I bought a small outboard gas can, cut off the end, and put in two gallon of diesel. When I had to bleed I removed the fuel line from the filter and attached the emergency tank. A few squeezes of the bulb on the hose and she would start right up. Maybe on one occasion I had to bleed from the top of one of the injectors. I carried that tank for eight years before repowering with a self-bleeding 3YM30.

Before that option I would open the bleed screw on top of the primary filter and touch the starter. Tighten that one and open an injector bleed and hit the starter again. Tighten that one and it would start assuming that "air" was the problem.

 

[Steve Dion]

Gary: On my 2GM we only needed to loosen the bleed screw on the top of the engine mounted filter. It is the 10mm with a phillips head slot. I have quite often used the key to pump the fuel rather than the thumb pump on the fuel pump.

I doubt that you will need to go the high pressure side of the system to bleed any air.

Good luck!

 

[Snotter]

Last month I bought an electric 12 volt fuel pump designed for pumping diesel from a local autoparts store. I put it between the Racor and the engine. I crimped battery aligator connectors at the end of the power cord and hook it up only for bleeding the system. It remains disconnected the rest of the time, even while running the engine. The fuel passes through the pump when it is off with no problems. I installed the pump while replacing all the fuel lines between the tank and the engine. I was tickled pink that I didn't have to bleed the engine after replacing the lines. Connecting the electric pump to the battery terminals for a minute or two was enough to remove all the air in the lines and the racor. The air exits through the return line from the engine. I wonder if I can get by with just running the electric pump to bleed the system when I change my secondary filter? I will find out in a few weeks when I attempt it.

On my perkins 4-154, you can grow old pumping that damn lever on the manual pump. What a hideous process.

 

[Deadhead]

Bleeding Fuel System

I changed both the primary & secondary fuel filters on my 3YM30 prior to beginning this season. Simple & intuitive procedure really - I removed the bowl on the primary Racor, changed the element, & partially refilled the bowl with clean fuel before putting it back together.

I then replaced the engine mounted secondary filter element & again partially refilled the bowl with clean fuel before putting it back together. I bled the system by cracking the hex nut/philips screw on top of the secondary filter & pumping the hand lever until fuel flowed freely out of the opening. Retightened the screw & 'fired that mother up'. No problems at all. I did replace the nylon washer on the bleeding screw. The next weekend I motored from Riverside, NJ to Georgetown, MD. A total of about 12 hours with nary a hiccup.

I am just finishing up installation of a Floscan fuel flow monitoring system and a vacuum gauge in my fuel system. I am going to install a squeeze bulb in the engine supply line to facilitate bleeding the fuel system going forward. There are 2 large dampeners & maybe 20' of 5/16" fuel line to fill with diesel. That little hand lever would probably fail due to fatigue before I was finished.

Has anyone ever tried using a bicycle pump to pressurize the entire system through the fuel tank vent? I came across this link recently:

http://www.diybob.com/HotBrightIdeas.htm

Regards.
Ted

 

[Deadline2]

Easier

Fill the fuel filter cannister nearly to the brim.
Then use a West syringe to top it off from the side.
Be careful not to overtighten the alumnimum cannister.
That will strip it, requiring a new cannister or entire pump.

 

[Benny]

Not sure about the 2QM but on the 2GM you only have the bleed screw on top of the secondary filter. Open the screw placing a rag over it to catch spilled fuel and crank the engine with the starter. When the engine starts is your cue to shut off the screw. There may still be some air in the lines so start increasing RPMs in increments of 500 and letting it run for a minute at each interval. By the time you get to 4000 rpm all the air should be clear.

 

[Paul F]

A QM engine is different than a GM, you may have to bleed after the high pressure pump and you will have to bleed at the injectors. Also, moving the return fuel line from the secondary filter to the tank is required. Here is my story of bleeding a 2QM15 after replacing a failed fuel pump. Gary let us know how the bleeding process is going otherwise we do not know if these comments are helping you.
http://forums.hunter.sailboatowners.com/showthread.php?p=579166#post579166

 

[garylinger]

Thanks all for your suggestions/input. I have been away from internet service since Friday morning and now just catching up. I hope to try the suggestions tomorrow after reinstalling my manifold and mixing elbow. I'll let you all know what happens.

 

[John T1594]

I had a 2QM15 on my previous boat. Bleeding the fuel system after a filter change is relatively easy. First of all, the secondary filter (on the engine) is mounted high and above the level of the injector poump. That means that any air that is trapped in the filter can be bled off via the bleed screw and none will get to the injector pump or to the injectors - as long as you don't run the engine before bleeding the system. Therefore, you only have to bleed the filter and not the whole system. To bleed the air, simply open the bleed screw on top of the filter housing and operate the fuel lift pump until you get a clean and bubble free flow of fuel. BTW the 2QM15 does not have a return fuel line - seems to work fine without one.

 

[Paul F]

Fuel system diagram

The pictured diagram below shows the routing of the 2QM15's fuel system. As John says if the engine ran and all that is changed is the filters, bleeding the secondary may be all that is needed. I replaced the hoses and fuel pump and had a hard time restarting the engine. After rerouting the return fuel pipe to the fuel tank the engine runs as well as it had before.

 

[garylinger]

Re: Fuel system diagram

I finished but it is something that I would rather never have to do again. John, my 2QM15 DOES have a fuel return line. It Ts into the top of the engine mounted filter. My main filter (coming off of the tank) was a Fram 1191A which I could not find locally so I went to NAPA and got their equivalent. After putting it on and trying to pump fuel with no luck I took it off and looked at it. I think it is a defective filter since it only has a hole in the center (top and bottom) with no holes to allow for fuel flow (as the Fram does). I put the Fram back on and continued trying to pump fuel. I finally got a stream out of the top of the engine mounted filter (thru the bleed screw) and tried to start it - no luck. I then bled the banjo fittings at the injectors and tried to start it - no luck. After getting no where I sprayed WD40 into the air intake and finally got it to sputter and after several more squirts, cranks, squirts, cranks it finally ran on its own and is now running well. I'm going to go back to NAPA and check about that filter.