Yanmar Diesel Question

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Jul 7, 2009
218
Catalina 30 Mark I Stockton, Mo
Hello all:

I am rehabbing a 1976 Catalina 30. I ran the engine before I bought the boat, so I know that it ran then.

Since then, I have replaced all of the fuel lines from the tank to the engine. I opened the tank and cleaned out the gunk that was in it. I cleaned out the fuel filter and replaced the filter element. I pushed fuel through all of the lines to make sure that I had clean fuel throughout the system.

I managed to get the engine to start and it would run for about 30 seconds, then die. There is an electric fuel pump in the system before the filter...does this need to be running to keep the engine going? I'm not 100% sure that it is running, and so it becomes an easy target to fix. When the engine is running, it seems to run OK, responds to throttle, etc, but won't stay running for very long.

Thanks for the help!
 

jrowan

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Mar 5, 2011
1,294
O'Day 35 Severn River, Mobjack Bay, Va.
I used to have a Yanmar diesel very similar to yours. I didn't even know that Catalina put Yanmars into a '76 C - 30. I thought that they were all Aotmic A4's 'till around 79-80. Anyway, it really sounds like you have an air blockadge somewhere in your fuel lines. My Yanmar had a mechanical fuel pump, not electrical which is more common for the early Yanmar engines. It also should have a manual fuel lifting pump which has a tiny lever on it that allows u to manually prime the motor to draw fuel from the tank to the engine, before cranking the starter. U have to pump it about 50 pulls to get any fuel through the lines. Then crack open the fuel-air bleeder retaining nuts at the main fuel pump, & at the injector fittings to release any air in the lines. Only crack the bleeder nut a 1/4 turn, just enough to let out any air without introducing more. Crank the engine while the nut is cracked open to allow the fuel pump to push out any air in the lines. Yanmars can be a bitch to bleed out air when it's in the fuel lines. It may take 2 or 3 tries to accomplish. Also check links on this site on removing any mesh screens installed at the bottom of the fuel pickup tube at the bottom of the fuel tank. This can also cause the situation that u describe. Good luck.
 
May 10, 2004
180
Catalina 30 Puget Sound
Is this engine a YSE12? If so, I can help. My '76 has the same engine. Love the engine, but it took a while to learn everything about it. One small problem at a time for 15 years....... heh heh.
 
Jul 7, 2009
218
Catalina 30 Mark I Stockton, Mo
Thanks for your help, guys. I wound up putting in a new electric pump, cleaned and primed all of the lines, then cranked it with the throttle up a bit and the decompressor open...it fired right up when I closed the valve! Ran great from idle to full throttle. I was amazed at how smooth it was at full throttle...like butter! It idles great, the new single wire always on alternator worked great - 14 VDC the whole time. I am really looking forward to getting on the lake now! I wasn't even sure the thing would run.
 
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