Get my engine running.

monocerosin

monocerosin

.
Apr 10, 2023
73
Hunter 37c Port of Madison
Yanmar 2qm20 attempt

See video^^^^ it's short.

ok gang! We are working hard on our Unicorn Hunter 37c getting her ready to go back in the water.
The lift pump diaphragm might be bad. I feel no suction from the tube. It's out of frame but I have a small container with diesel sitting in front of me. It does not seem like the hose pulled any fuel.
I put new fuel in the filter cup and closed it tight. I opened the bleeder screw there but did not get any fuel there as we cranked the motor.
Engaging the compression (or is it engaging the decompression?) By pushing the arm aft on the engine almost made it want to start.

I'm not actually trying to start it as much as I just want to bleed the lines of air and get clean fuel through.
Before I stopped to rethink the situation, the last crank almost turned over and it coughed some black smoke out (I have the exhaust pipe removed from the elbow so I can see what's happening) and that made me hesitant to do any more experiments.

I have a new lift pump I can put on and try that. Otherwise maybe I can hand cranit the engine to see if I can get it to pull fuel up to the filter? Any advice or tips will be appreciated. You guys are the best!
 
Johnb

Johnb

.
Jan 22, 2008
1,461
Hunter 37-cutter Richmond CA
Are you referring to the crankshaft driven pump that is on the starboard side of the engine?

If so then rotate the engine until the hand pumping lever on the pump is free to move. Then operate the lever until either you get fuel out of the bleed screw or your hand falls off.

If neither ever happens the pump may be bad.

With the decompression lever pushed to the rear the engine will never start.

You may have to bleed more than once.

Don’t crank for long enough to flood the exhaust with cooling water.

I have been through this after changing filters and long ago after changing that pump.
 
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monocerosin

monocerosin

.
Apr 10, 2023
73
Hunter 37c Port of Madison
Johnb said:
Are you referring to the crankshaft driven pump that is on the starboard side of the engine?
Then operate the lever until either you get fuel out of the bleed screw or your hand falls off.
If neither ever happens the pump may be bad.
Click to expand
This answers several questions and brings a few more.
Now I see the difference between the "fuel injection pump" and the "fuel feed pump"
More things to explore.
I have the other manual also but this is generally the route I am taking.
Dear Neptune I don't want to open that up.
Thank for for your help!
 

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Johnb

Johnb

.
Jan 22, 2008
1,461
Hunter 37-cutter Richmond CA
Just to clarify. They are both camshaft driven mechanical pumps. The one I am recommending you to manually operate is labeled fuel feed in your diagram and pumps not the on engine fuel filter in the same diagram.
 
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D

dlochner

.
Jan 11, 2014
12,925
Sabre 362 113 Fair Haven, NY
The lift pump (aka, fuel supply pump) simply provides fuel to the injector pump. It is a simple diaphragm pump. These pumps are know fail after awhile and can be relatively easy and cheap to replace.

The injector pump is a complicated pump that provides high pressure fuel to the injectors. Serviceable, but better serviced by a well trained and experienced mechanic than a DIY guy. Injector pumps do fail but not as frequently as lift pumps.
 
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monocerosin

monocerosin

.
Apr 10, 2023
73
Hunter 37c Port of Madison
dlochner said:
The lift pump (aka, fuel supply pump) simply provides fuel to the injector pump. It is a simple diaphragm pump. These pumps are know fail after awhile and can be relatively easy and cheap to replace
Click to expand
This is the part that I have new and can replace. Already SBO is giving me answers and things to work on tomorrow, thank you!
One step at a time!
 
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Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,251
Hunter 310 West Vancouver, B.C.
monocerosin said:
Already SBO is giving me answers and things to work on tomorrow, thank you!
Click to expand
We also like to suggest things before they even come to your mind. It's annoying, but that's just how we are.

If you do replace your "lift pump" as it's called, this suggestion may save you an additional $100.00 by avoiding having to purchase another pump after buggering up hte firsy replacement. The lift pump is held in place by two bolts as shown below :

1723222510524.png


You will find that as you try to insert the replacement pump and gasket into the block, the arm will catch on the side of its cam. You will never know it's misaligned unless you are right behind the pump and wee it's misaligned. Once the two bolts are tightened, the aluminum arm is bent thus destroying the pump.

In order to avoid this mind numbing disaster, insert two studs (bolts without heads) into the block finger tight and then hang the pump on the two studs. Install nuts on the studs finger tight to ensure the pump is in the correct position and then replace the studs, one at a time with the original bolts.

I had to install my pump blind hence the problems :

1723223665872.png



I eventually got away from the cam driven pump and went with an electric pump :

1723223791839.jpeg
 
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monocerosin

monocerosin

.
Apr 10, 2023
73
Hunter 37c Port of Madison
a5c2df01-42c2-499c-88b2-bf0838d54d26-1_all_45.jpg


I think bypassing this old thing and going electric sounds great. I'm going to start pricing those parts, I'm sure I will have more questions.
 
Ralph Johnstone

Ralph Johnstone

.
Jan 4, 2006
7,251
Hunter 310 West Vancouver, B.C.
monocerosin said:
I'm sure I will have more questions.
Click to expand
We here have the ability to read minds so I will anticipate your questions : Yes, the lift pump is directly wired to your ignition switch to ensure you have fuel at the injection pump before the engine starts cranking. Yes, you want a lift pump which will pass fuel under the force of gravity if it should fail or lacks power.

This is shown here for the pump I chose :

1723242906530.png



1723243043397.png



1723243709419.png



1723243810162.png


The CUBE is only one of several on the market.
 
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rardiH36

rardiH36

.
Jun 21, 2007
2,117
Hunter Cherubini 36_80-82 Sausalito / San Francisco Bay
I don't check in the forum very much anymore. But I did today. Reading down from the moncerosin's original post, I was also going to suggest installing an electric fuel pump. But Ralph beat me to it. Plus his contribution is much much more informative than what I might have presented!

I have a 2QM20.

Same as monocerosin, the first time I needed to bleed my fuel lines, I found that the finger pump was no help at all.

During my first new owner look-see into the engine compartment, I noted that the previous owner had installed an electric pump between the Racor filter and the engine. The wiring to it was disconnected. Also in the engine compartment, close to the finger pump, was an electrical switch -- also not connected to 12V. Being my first boat and new to diesel engines, I had no idea why the switch was there. So I removed it. But left the pump in place. Didn't seem to be doing any harm. Only several years later, when I needed to accomplish my first bleed, did I put 2 and 2 together. As Ralph has specified, my electric pump is the type that will let fuel flow through even when not energized. My engine starts and runs fine without power to the electric pump. So the default is "off". But when energized, the electric pump is excellent for bleeding. I ultimately mounted an on-off switch for the electric pump in the engine compartment. I only power it up for the need to bleed. With the switch right there, as soon as fuel starts flowing without bubbles from the cracked-open banjo fittings and bleed screws, power can be turned off quickly to avoid too much of a mess.

Monocerosin: It seems that you have the official Yanmar Service Manual for the QM series engines? If so, specific bleeding instructions are on page 13-8. Let me know if you don't have the manual. I can then PDF the two pages and post.
 
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isaksp00

isaksp00

.
Apr 27, 2010
1,279
Hunter 23 Lake Wallenpaupack
monocerosin said:
Yanmar 2qm20 attempt

See video^^^^ it's short.

ok gang! We are working hard on our Unicorn Hunter 37c getting her ready to go back in the water.
The lift pump diaphragm might be bad. I feel no suction from the tube. It's out of frame but I have a small container with diesel sitting in front of me. It does not seem like the hose pulled any fuel.
I put new fuel in the filter cup and closed it tight. I opened the bleeder screw there but did not get any fuel there as we cranked the motor.
Engaging the compression (or is it engaging the decompression?) By pushing the arm aft on the engine almost made it want to start.

I'm not actually trying to start it as much as I just want to bleed the lines of air and get clean fuel through.
Before I stopped to rethink the situation, the last crank almost turned over and it coughed some black smoke out (I have the exhaust pipe removed from the elbow so I can see what's happening) and that made me hesitant to do any more experiments.

I have a new lift pump I can put on and try that. Otherwise maybe I can hand cranit the engine to see if I can get it to pull fuel up to the filter? Any advice or tips will be appreciated. You guys are the best!
Click to expand
 
isaksp00

isaksp00

.
Apr 27, 2010
1,279
Hunter 23 Lake Wallenpaupack
Hmm, didn't consciously post that. Not sure what happened... Maybe fat fingered on the phone.
 
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