73 302/5.0l mercruiser

ok folks. im james its my first time to post here as I just became a member. yesterday I had taken my 1973 caravelle trihull out to the lake. It ran like a champ for about 45 min then I noticed a change on my vac. guage. I was loosing vac. off the intake. and then the engine wouldn't run over 2000 rpm. after getting closer to the dock I had shut the engine off to coast in as there was others putting and taking boats out. after dock cleared I couldn't get engine to fire up even in "neutral" so I had to jump I and swim to bank and pull the boat in. is there anything to have a look at other than fuel filter?

is there anything to have a look at other than fuel filter?

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Ayuh,.... That's where I'd start,....

More importantly, what's In the old filter,....

caravelleboater1973 said:

1..... then I noticed a change on my vac. guage. I was loosing vac. off the intake.

2..... and then the engine wouldn't run over 2000 rpm.

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You'll do much better if you'll post your questions in the Mercruiser forum.

1..... a vacuum gauge on a Marine Engine is rather useless. When under load (and a Marine Engine is typically under load when above hull speed), manifold pressure drops substantially. This is because the throttle plates are well open enough to meet the engine's fuel/air demands for heavy loads. On a car/truck the dynamics are quite different.

2.... have you looked at your ignition's progressive advance and total advance?


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