Both Motors Running very Rich at idle

[Natesms]

Last spring I rebuilt both carbs because the motors were running rich at idle (in addition to the smell and smoke sometimes you could see a bit of fuel on the surface of the water). I rebuilt one, 2 weeks later did the other. Everything ran fantastic for most of the summer. No smoke, smooth idles and no hesitation. Then in September the first motor started running rich again at idle shortly followed by the other. I checked float levels per holley tech support and everything looked fine. I've never had a single problem with bad idles, hesitation, motors dying or anything like that. They both just run really rich at idle.

Anyone have a suggestion on where to start in the spring? I'm debating rebuilding them again using Holley kits and not sierra's as I was not impressed with the gaskets.

 

[alldodge]

Last spring I rebuilt both carbs because the motors were running rich at idle (in addition to the smell and smoke sometimes you could see a bit of fuel on the surface of the water). I rebuilt one, 2 weeks later did the other. Everything ran fantastic for most of the summer. No smoke, smooth idles and no hesitation. Then in September the first motor started running rich again at idle shortly followed by the other. I checked float levels per holley tech support and everything looked fine. I've never had a single problem with bad idles, hesitation, motors dying or anything like that. They both just run really rich at idle.

Anyone have a suggestion on where to start in the spring? I'm debating rebuilding them again using Holley kits and not sierra's as I was not impressed with the gaskets.

Put a vacuum gauge on the engine and see what it tells you. A compression test would also be a good thing to check status

 

[Natesms]

Put a vacuum gauge on the engine and see what it tells you. A compression test would also be a good thing to check status

I can do that. I compression checked them a couple years ago, have never put vacuum on them though so I won't have a starting point for comparison there.

The thing that is bugging me is that they ran perfect right after the rebuilds and then both went rich again after roughly the same amount of time. And remember there are 2 of them. I'm hoping there is a suggestion like "you might have messed up X" while rebuilding the carbs. EX: I read that the power valve seals often get put in incorrectly.

 

[alldodge]

If there is a common theme, and that is a big if, then look for the place where you buy gas. Wouldn't be the first time the Marina is buying some real crud, but as before that's a big if

 

[frank246]

Check for carb flooding at idle.
Might be float needle and seat issue.

 

[Natesms]

Check for carb flooding at idle.
Might be float needle and seat issue.

Checked that and it looked good. I've been debating making the floats a little lean because the motors sit at a slight reward tilt. If the carbs had external adjustments it would be a lot easier. Drives me nuts having to tear the bowls off to do float adjustments.