6BTA5.9M 250HP idle

[glenn maerki]

i seem to have the temperature creep problem solved….but now a new issue popping up on the same engine. When cold the engine idles well, when hot i get a pretty significant “misfire”. looking at the tach I can see a 25+ rpm “miss” as the engine is idling. If I bump it up to 1000 rpm it smooths out. no smoke once the engine is warm…at idle or at high rpm. Almost seems like water in the fuel. The starboard engine is running off the same fuel tank and running very well so don’t believe it is a fuel issue. I changed both primary and secondary filters less than 20 hours ago. I cracked each injector line hoping to identify the bad cylinder. no matter what line I loosen the result is the same….the engine seems like it is going to quit. I’ve done that before (loosening lines) on this engine and the starboard engine and as expected the engine rpm drops off but never thought it was going to quit. I tried to post a short video but file size is too large. Any suggestions on things to check is greatly appreciated. thanks!

Topic

[Francis Valerio]

If you can upload to youtube then you can just post a link. Then no worry about the file size. Where is the boat on Long Island?

[Tony Athens]

Look at/monitor fuel pressure at the on-engine filter.. Not easy to rig it up but that’s what you need to do.. Use a 0-30 Liquid filled gauge on a 6-10 ft small ID hose with 2-3 loops in it to dampen the readings..Or, just buy new genuine lift pump and install it.

Next—–the CAV injection Pump you most likely have can and does wear internally——————————————How “OLD” is it?

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