loud popping sound from carb at WOT

[ratking20]

just started doing this? doesnt seem to be as fast as it was before either? what could be causing this????

260hp 5.7 mercruiser i/o alpha one

 

[Tahorover]

Re: loud popping sound from carb at WOT

it means it is lean

 

[fossill]

Re: loud popping sound from carb at WOT

Or cam lobes worn

 

[bcasey22b]

Re: loud popping sound from carb at WOT

or it has a bent push rod or the rocker came off not letting the valve open all the way or at all

 

[Evinrude Boater]

Re: loud popping sound from carb at WOT

I agree with Tahorover, commonly known as "lean pop". Mine did that when the carb filled up with fan belt dust. My pulleys were rusty and it chew up the belts. The rubber dust clogged the carb creating the lean pop when accelerating.
I would troubleshoot the fuel system before considering internal engine components. When was the last time the carburetor was cleaned internally?

 

[ratking20]

Re: loud popping sound from carb at WOT

How can I adjust the carb so it isn't running lean???

 

[Evinrude Boater]

Re: loud popping sound from carb at WOT

If this just started recently then I would expect something is clogged preventing the proper flow of fuel. I don't think you should be adjusting to compensate for a problem, find and fix the problem.

 

[ratking20]

Re: loud popping sound from carb at WOT

how about that carb clening stuff u ad to the gas? is that worth using or is it crap???

 

[Bondo]

Re: loud popping sound from carb at WOT

how about that carb clening stuff u ad to the gas? is that worth using or is it crap???

Nope,... Mechanic in a can rarely works,...

Tearin' the carb apart, 'n kittin' it is a 50/ 50 shot fer most Diy'ers...
But that's what needs doin'...

 

[fossill]

Re: loud popping sound from carb at WOT

Tearin' the carb apart, 'n kittin' it is a 50/ 50 shot fer most Diy'ers...

Those are pretty generous odds.

 

[christoner2002]

Re: loud popping sound from carb at WOT

My suggestions are check compression. See where you are at on all 8 cylinders. My 5.7 had 4 burnt valves. Also, by any chance, is it popping as soon as you take it out? Or only after it warms up? My coil on mine would boil once the boat was run for about a hour. Caused a severe pop, and miss at upper rpm. Just a coiple things to look at

 

[ratking20]

Re: loud popping sound from carb at WOT

no popping when it starts up, only when i push it almost to WOT, when i slow back down it stops

 

[Bondo]

Re: loud popping sound from carb at WOT

no popping when it starts up, only when i push it almost to WOT, when i slow back down it stops

Ayuh,... It's goin' Lean, at the point of the highest fuel usage...

 

[grendelsniper]

Re: loud popping sound from carb at WOT

could be fuel pump getting weak not having the pressure at wot

 

[Gettinther]

Re: loud popping sound from carb at WOT

just started doing this? doesnt seem to be as fast as it was before either? what could be causing this????

260hp 5.7 mercruiser i/o alpha one

Common problem with GM v8's is broken rocker, or cam lobe worn off (compression test) otherwise lean fuel supply at WOT.
If popping at WOT is steady and rythmic check rockers and cam, might just be the rocker nut backed off(replace nut) again compression test, will tell if the problem is mechanical.