1987 Mercruiser 454 Loud 'Popping Noise'

[NorCalNomad]

I have an occasional loud popping noise coming from the engine. Noise occurs during hard acceleration, if I back off and accelerate slowly it doesn't do it. Also it will rarely occur at cruising speed, but seems to coincide when an additional electric load is added, such as adjusting the trim. Also, I am hoping to be educated in the proper terminology here, is it misfiring, detonation or something else? Any input appreciated.

 

[Scott06]

Probably a lean sneeze due to running lean . Would look at fuel supply and carb rebuild. What do the spark plugs look like ? Would bet they look lean

 

[kenny nunez]

Does your engine have the original ignition system? Has there been any carburetor work done recently? With an ohm meter check the resistance of the coil and spark plug wires. Any idea how long the spark plugs have been in service? Be sure that all electrical connections at the ignition switch and on the back side of he instrument panel are tight.
Replacing the spark plugs might cure the problem. When they start to break down you will get a pop out of the flame arrestor under a load.

 

[NorCalNomad]

I removed the carb and installed a Holley Sniper EFI system. Also found a bad wire between coil and distributor. Todays the maiden voyage with the EFI system. Wish me luck.

 

[Swedefj40]

I removed the carb and installed a Holley Sniper EFI system. Also found a bad wire between coil and distributor. Todays the maiden voyage with the EFI system. Wish me luck.

How'd the maiden voyage go? Interested in the Sniper install myself.

 

[04fxdwgi25]

How'd the maiden voyage go? Interested in the Sniper install myself.

You know that last post was July 8 '23, right, and he hasn't been here since.?

 

[Swedefj40]

Yeah, just curious.