Volvo 4.3 GL popping at 3000 RPM

[dgauci]

Hi all,

I have a 24' 1983 Sea Ray with a 3 year old Volvo 4.3 GL engine/SX Leg with 125 hours on it. Since I started using it after the winter ,I'm getting a dull popping sound when I get it up to 3000 RPM. I back off the throttle and it goes away. I've tried to get it to make the same noise when onshore but when there's no load, It seems to be fine.

Last year I changed the plugs, distributor, fuel filter and it was fine afterwards. I thought it may be water in the tank but I added a fuel conditioner and its still popping under load. I haven't touched the timing yet.

Any suggestions?

David

 

[IVAZ]

Re: Volvo 4.3 GL popping at 3000 RPM

Welcome to iboats.
You mean backfiring? Where is the noise coming from?

 

[dgauci]

Re: Volvo 4.3 GL popping at 3000 RPM

Seems to be emitting the offending noise from the carb area.

 

[IVAZ]

Re: Volvo 4.3 GL popping at 3000 RPM

Lean condition is usually the culprit for backfiring. Is your fuel old? Check the fuel filters. Start with the simple stuff first.

 

[TilliamWe]

Re: Volvo 4.3 GL popping at 3000 RPM

Is the bottom of the boat clean? Can it get over 3000rpm? What is the WOT RPM? How's the prop?

 

[Don S]

Re: Volvo 4.3 GL popping at 3000 RPM

A friend of mine put a new 4.3 in his a few years back and had a similar problem. Turned out to be valve seals. Seems he had to remove some from either the exhast or intake valves not sure which. But I did just email him to see if he remembers.
I didn't do the work, so don't remember all the details.

 

[dgauci]

Re: Volvo 4.3 GL popping at 3000 RPM

I tried some carb cleaner and it seemed to go away at 2900 rpm but when I hit 3300, we did a collective sigh until we got one loud pop, then we throttled back. Then I tried running it to near empty, then added new gas..same thing.

I'll try changing the fuel filter this week and am almost tempted to remove the fuel tank and drain it as I suspect that after 25 years, there could be gunk in the bottom of the tank. I'll do the timimg as well as its not been done for a few years.

Will keep you posted and thanks to all that have commented with suggestions. I've got to be getting close.

David