5.7L (carb) Issues-gctid806263

[Douggy]

My 2003 245 with the 5.7L (carb) is having issues. I get smoke with soot and the idle stays high (>10k) even after it's warmed up. I'm going to start with a visual inspection and some carb spray cleaner. I'm wondering if the choke is not working properly.

Any suggestions would be appreciated.

[builderdude]

"Douggy" post=806263 wrote:
My 2003 245 with the 5.7L (carb) is having issues. I get smoke with soot and the idle stays high (>[strike]10k[/strike]) 1k :whistle: even after it's warmed up. I'm going to start with a visual inspection and some carb spray cleaner. I'm wondering if the choke is not working properly.

Any suggestions would be appreciated.

Good place to start. maybe the + wire came loose.

[Four_Pyrates]

Well, 1K is high. I agree...check the electric choke. All the symptoms are there.

[Douggy]

Well, I took a look and found that the choke was still connected electrically, it gets ~13 volts when running the engine. I did however see that the choke was more than half way open at cold. I sprayed carb cleaner on the choke linkage and then adjusted the choke back to almost closed at cold. Started it up and it ran normal and the choke slowly started to open. After a few minutes I gave the throttle a goose and the choke opened up almost all the way. When I ran the rpm's up the choke would open all the way. The idle is now ~780-800 rpm's and run's pretty smooth.

[builderdude]

Sounds like you maybe had some sticky choke linkage then and she's running smoothly. Not sure what carb you have but another thing to check are the idle air bleeds around the air horn, they can become plugged up over time, this can also cause a super rich idle circuit.

[Douggy]

It's the stock mercruiser 2 barrel (#864943A01).

If the choke was basically open when cold would that cause the symptoms I experienced?

[dmcb]

An open choke would only make it a bit harder to start. I would expect to see a closed choke when warm to see what you experienced.

Doug

[builderdude]

Agree with Doug, idle may be a touch on the high side. Mine idles around 650-700

[Douggy]

"dmcb" post=806442 wrote:
An open choke would only make it a bit harder to start. I would expect to see a closed choke when warm to see what you experienced.

Doug

I'm going to run it some more and see if the problem returns. With my luck it will return when I get it back on the water.

[Douggy]

"builderdude" post=806444 wrote:
Agree with Doug, idle may be a touch on the high side. Mine idles around 650-700

I'll try lowering the idle and do some more carb cleaner.

[2850Bounty]

"Douggy" post=806452 wrote:


I'll try lowering the idle and do some more carb cleaner.

Look into the upper area of the throttle bores. You will see several small brass air orifices that lead into the low speed fuel metering circuits.

Using the red "straw" on the carb cleaner spray can, give each one a good blast.

Wear eye protection!

This should clear out these passages that may have become blocked or restrcted.

[Douggy]

"2850Bounty" post=806505 wrote:

"Douggy" post=806452 wrote:


I'll try lowering the idle and do some more carb cleaner.

Look into the upper area of the throttle bores. You will see several small brass air orifices that lead into the low speed fuel metering circuits.

Using the red "straw" on the carb cleaner spray can, give each one a good blast.

Wear eye protection!

This should clear out these passages that may have become blocked or restrcted.

Thanks, I'll try that.