possible carb issue?

[mikemj]

i have a 2000 volvo penta 4.3 gl pefs engine boat runs good on start up. recently it started to backfire thru carb.loses power then regains it back . carb is a holley 2300. it seems like it only does it when in in rough water or when running thru waves from fellow boats.it happened when running to the scallop grounds crystal river. doesnt do it when on the lake tubing etc. carb been rebuilt but thinking time to get new carb.timing is good and have done plugs and wires ,ff etc. now i have replaced the ignit mod with one from a auto store could this possibly be the issue.

 

[dypcdiver]

Guessing here, are you sure you got the float height right?

 

[mikemj]

Not sure i didnt rebuild it and its a sx driveBut is it hard to set the float level

 

[alldodge]

i have a 2000 volvo penta 4.3 gl pefs engine boat runs good on start up. recently it started to backfire thru carb.loses power then regains it back . carb is a holley 2300. it seems like it only does it when in in rough water or when running thru waves from fellow boats.it happened when running to the scallop grounds crystal river. doesnt do it when on the lake tubing etc. carb been rebuilt but thinking time to get new carb.timing is good and have done plugs and wires ,ff etc. now i have replaced the ignit mod with one from a auto store could this possibly be the issue.

:welcome: to iboats

Agree, probably float but could also be a weak fuel pump or restriction. Suggest getting a vacuum fuel pump gauge and check the fuel pressure. Put a Tee between the pump and carb, should be 4 to 7 psi. Would be great if you could leave it in line so to check when your running.

When was the last time the fuel filter was changed?

 

[DaveM]

I agree with the others, backfiring through the carb usually is a fuel starvation issue. Think about what the ambient temp was when this has happened. Heat will increase the impedance of electrical circuits if there is corrosion on the fuel pump power connections. Or in other words, your fuel pump may be failing.

 

[mikemj]

I will check pressure this weekend looked at the 7.5 fuse by pump and it was like melted inside the plastic housing where it sits . I ll have to redu the fuse housing this could be the prob bouncing in the waves could be shaking the fuse contacts is it suppose to be a 7.5 or a 10 amp fuse. The put a new pump on when i bought the boat before summer only had it out a few times maybe 4 times.will also get new ff fri and see if any water is found.