CARBON FILM ON BACK OF BOAT

[rs1lollie]

After a day out on the lake, some trolling speed and some racing around the lake speed I have carbon film around the out drive water line, engine runs great, its a 1998 four winns 180 horizon rs, volvo 4.3gl gm vortec black/ dark grey block, with a sx out drive, holley 2 barrel carb. I have a bottle of berrymans total fuel cleaner in 20 gal of non oxy gas along with some sta-ble in it. do you think after this tank that carbon film will go away?? or should I do a complete tune up / carb rebuild...

 

[ondarvr]

A carbon build normally means it's running rich, Berrymans might help, the sta-bil will do nothing, and neither will the E-0 fuel. Best to clean and adjust the carb.

 

[rs1lollie]

A carbon build normally means it's running rich, Berrymans might help, the sta-bil will do nothing, and neither will the E-0 fuel. Best to clean and adjust the carb.

the only adjustment i see on the holley carb is idle and accelerator pump, does any one know how and a diagram

 

[jimmbo]

No Title

There are two Idle mixture screws, they are located, one on each side of the of the metering block

 

[rs1lollie]

There are two Idle mixture screws, they are located, one on each side of the of the metering block

Thanks for the pics, I will look for them. Now how to correctly adjust them???

 

[spoilsofwar]

Does your boat have a notched transom? Where the Outdrive is set back a bit and there are "pods" on either side of it? And is there a built in swim platform above it? If so, then the exhaust film is the effect of the transom shape trapping the exhaust in that area. My boat has this type of transom, and a similar driveline, and has had this issue since new. I just clean it after each use to try to keep it from getting too out of control.

I would not diagnose your boat as running rich by looking at hull scum... The plugs will tell you a much more accurate story.

If you have a smooth, "normal" transom, then you may have an actual issue.

 

[jimmbo]

Thanks for the pics, I will look for them. Now how to correctly adjust them???

I use a vacuum gauge. Running in gear, adjust for highest vacuum

 

[rs1lollie]

Does your boat have a notched transom? Where the Outdrive is set back a bit and there are "pods" on either side of it? And is there a built in swim platform above it? If so, then the exhaust film is the effect of the transom shape trapping the exhaust in that area. My boat has this type of transom, and a similar driveline, and has had this issue since new. I just clean it after each use to try to keep it from getting too out of control.

I would not diagnose your boat as running rich by looking at hull scum... The plugs will tell you a much more accurate story.

If you have a smooth, "normal" transom, then you may have an actual issue.

I have the typical four winns notched transom.

 

[spoilsofwar]

I have the typical four winns notched transom.

Then I highly doubt you have any issue at all and need to be fiddling with your carb. If the exhaust film is extreme, maybe, or is much worse then it used to be (assuming you've owned the boat for multiple years).