Engine issue

[Yorkshirelad]

Hi all,
Filled up with gas, pump out, took her out on the lake. Engines running great, cruising at 1500 to 1800 rpm, when jacking her up to get on plane port engine starts to miss. Bring the rpms back down runs great?
Going to call the marina tomorrow to check it out, I’m leaning towards electrical issue?
Cheers Rob

 

[sbw1]

The last complete tune up with everything new including spark plug wires was when?

 

[Yorkshirelad]

View attachment 107424
The last complete tune up with everything new including spark plug wires was when?

That would be 3 years ago!

 

[sbw1]

Try running it at night with the engine hatch open. If you see lots of blue sparking around the spark plug wires that is likely the cause of the loss of power. Older 454s are known to be hard on plugs and wires. You are due for a tune up if the boat has been run much in the past 3 years.

 

[Dustin Brewer]

I had a similar issue that I finally fixed. I replaced cap/rotor, coil, cleaned and tightened the connections and grounds to include the 10 pin behind the motor, and fuel/water separator...none of it worked. Finally I put a multimeter on the alternator and it was cranking out 11 volts. Replaced the alternator and new cranking battery and problem solved! Thinking the low voltage was causing the ECM to get angry and shut down and back on again.

 

[El Capitan]

Next place to look would be fuel contamination, fuel lines, fuel pump etc.