Yanmar 2GM starting trouble

Jun 26, 2013
13
Hunter 280 OK
Ruined a perfect day at the lake yesterday as my 1996 Yanmar 2GM would not start. Cranked fine but just would not fire. It ran flawless 3 weeks earlier after sitting for the winter. My first thought was air in the fuel system. I bled the system like I do when replacing fuel filters. Use the pump manual lever to get fuel from vent at secondary filter vent. Then cranked engine with cylinder relief valves open and water pump belt off. Usually one or two tries and it starts. This time no go. Went through same bleed procedure again and I noticed the manual pump stokes did not deliver fuel to filter vent but still getting fuel to vent when I cranked with cylinders unloaded. Then I cracked the lines at the injectors, which I have never done before, and never got any fuel there. I replaced secondary filter although it looked clean. I opened secondary filter and there was a little crud in the bottom, but filter looked good but did not have a replacement. Also cleared external tank vent which was somewhat blocked with spider debris. So..(sorry for long post)...looking for any help. Thinking maybe the fuel pump.
 

RoyS

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Jun 3, 2012
1,739
Hunter 33 Steamboat Wharf, Hull, MA
Sounds like air between the secondary filter and the injector pump. May be some sort of bleed device there.
 
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Likes: kloudie1
Nov 21, 2012
587
Yamaha 33 Port Ludlow, WA
Do you get fuel from the bleed scew just ahead of the high pressure fuel pump when you pump the lift pump lever?
 
Jun 26, 2013
13
Hunter 280 OK
Mermike. I did not bleed from the high pressure pump. I just loosened the fuel lines at the injectors but got no fuel there.
 
Jun 26, 2013
13
Hunter 280 OK
Thanks for the replies. I reviewed the Yanmar manual to find the bleed at high pressure pump. Will give that a go next trip to boat and will advise results.
 

Ted

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Jan 26, 2005
1,254
C&C 110 Bay Shore, Long Island, NY
Make sure your stop cable isn't binding in the closed (off) position.
 
Last edited:

19thol

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May 2, 2014
111
Hunter 30 St.Petersburg, Fl
Had a problem very similar recently, turned out to be a bad fuel line from the racor to the low pressure pump, changed it on a whim, started right up.
 
Jun 1, 2007
265
O'Day 322 Mt.Sinai
Couple of things.
1. No offense, but are you aware that the manual pumping action of pushing the lever on the fuel pump down is only effective for the very bottom of the lever stroke? If you push the lever down slowly, you'll feel resistance only at the very bottom 1/4" of stroke or so. If you don't know this and are rapidly pushing the lever down, you may not in reality be pushing fuel through the lines.
2. After a normal winter layup, you shouldn't have to bleed the lines at all.
3. If the temperature is below maybe 55 degrees or so, I find my 2GM20F hard to start as well. Yanmar recommends that you open the throttle to full, and crank the engine. As soon as it lites up, pull the throttle back. That method has worked for me in colder temperatures in NY.
4. If you do need to bleed, you can bleed from the exit of the secondary (engine mounted) fuel filter. Crack the exit fitting with a socket wrench, then stroke the pump until pure fuel comes out.
5. Try and start the engine.
6. if no joy, you can bleed the high pressure side at each injector. Crack the forward cylinder fitting, open the decompression levers and have someone crank the engine. You should see fuel piss out straightaway. then do the same on the rear cylinder, then start the engine..
7. Note that once you've bled the lines, you shouldn't have to do it again unless you've opened them and let air in for some reason. Even when I change my primary Racor filter, I rarely have to bleed the lines as long as I fill the filter bowl with fuel.

Hope this helps...
 
Sep 11, 2015
147
Hunter 31 Marina del Rey
I think the OP has the right idea, just follow the steps once more:
1) If you crank the manual pump, you need to see fuel at the fuel filter, plenty of it. If not, trace the lines.
2) If you see fuel at the filter, open the decompressors and crank for a while (I think you did this). It should start
3) If you are not getting fuel at the injectors, then start disassembling around the HP pump
 
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Likes: FlimFlamII
Jun 2, 2011
347
Hunter H33 Port Credit Harbour, ON.
The mechanical fuel lift pump is operated by a leaver that rides on the camshaft. When the camshaft rotates the fuel pump lobe moves the lever which in turn pulls down on the pump diaphragm. The alternating high point and low point of the cam shaft lobes cycles the diaphragm up and down. When you work the mechanical leaver of the fuel pump you are pulling the same diaphragm down. If the engine stops with the camshaft lobe pressing on the pump leaver the diaphragm will be partly or fully pulled down. In this situation the hand lever will not be able to work the diaphragm or will only be able to move the diaphragm a short distance. In other words, there is no pump stroke.

If this is the case the engine should be bumped over to get the internal lever sitting on the camshaft low point. This position will allow full diaphragm stroke with the hand lever. You will be able to feel the difference.

Always bleed a diesel at the feed to the HP pump before bleeding at the injectors. If there is air in or before the HP pump the fuel will not be pumped to the injectors.

Also, make sure that your fuel cut off lever is not stuck in the off position.
 
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Likes: Alan Gomes
May 24, 2004
7,129
CC 30 South Florida
Yes, try bleeding the air out at the high pressure pump. A slow leak could have developed in the lines and as the boat sat for three weeks it could have taken air in the lines. Once you get the engine running inspect all fuel lines and connectors for a fuel leak; usually fuel will leak out where air will leak in. 2GMs have a reputation for being hard to bleed as you may be experiencing.
 
Jun 26, 2013
13
Hunter 280 OK
Thanks everyone for your responses as I have learned much about the fuel system.
I wanted to update on issue. On my next trip to the boat I tried to bleed the lines at the secondary filter then the high pressure pump. No luck...using the mechanical lever on the lift pump did not deliver fuel to the secondary filter. Tried cranking with decompressors open, and no fuel anywhere except primary filter bleed. Yesterday, replaced the lift pump, successfully bled to secondary filter, cranked with decompressors open, closed decompressors and engine fired right up. Enjoyed a great day on the lake!
 

RitSim

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Jan 29, 2018
406
Beneteau 411 Branford
You can temporarily add a small piece of clear pvc tubing after the lift pump. If you have air, it will be visible. Bring small pieces of 1/4", 5/16", nd 3/8" id pvc from the hardware store. Also bring corresponding double hose barbs and clamps. Remove promptly after solving your issue.
 
Oct 29, 2005
2,355
Hunter Marine 326 303 Singapore
Thanks everyone for your responses as I have learned much about the fuel system.
I wanted to update on issue. On my next trip to the boat I tried to bleed the lines at the secondary filter then the high pressure pump. No luck...using the mechanical lever on the lift pump did not deliver fuel to the secondary filter. Tried cranking with decompressors open, and no fuel anywhere except primary filter bleed. Yesterday, replaced the lift pump, successfully bled to secondary filter, cranked with decompressors open, closed decompressors and engine fired right up. Enjoyed a great day on the lake!
Could you open up the faulty Fuel Lift Pump and see what could be learnt from it? I'm having somewhat similar issue with my 2GM20F and had taken out the Fuel Lift Pump. Stripping it but couldn't find what's wrong but will put in a spare unit instead, coming weekend.
Your experience here actually gave me some hope! Thank you.

Ken Y