Mercruiser 3.0L stalling when adjusting the throttle

[durban131]

Hello All,

I have a 1999 Bayliner Capri 1750 I/O with a Mercruiser 3.0L engine. Ive been having some issues as the boat seems to stall when adjusting the throttle. Im not a very mechanical person but Ive got some good advice on the iboats forum in the past and I would like to attempt to resolve this issue myself before I bring it to the mechanic and break out another thousand. Here is my attempt to best describe the issue:

(Sorry but my RPMs gauge is broken so I can not be specific regarding the exact RPMs)

1) Boat will *generally* start up fine.

2) The boat will generally engage and cruise at a slow no-wake speeds without issue.

3) The boat will generally cruise at a high speed without issue.

4) The boat does not like to cruise at "medium" speed. When adjusting the throttle to medium speed the engine usually either stalls or runs like the engine in this youtube video. (https://www.youtube.com/watch?v=mnkii1E0q1M)

5) Regardless of what speed Im cruising at, adjusting the throttle in either direction (slowing down or speeding up) usually results in the engine stalling.

6) It usually takes a couple minutes and some tinkering with the throttle to get the engine to start and run again.

7) I have noticed that the temperature gauge tends to swing wildly approximately around the times the engine is running poorly, and generally holds steady when the engine is running good. Could this be an electrical issue? Ive had electrical issues in the past.


Sorry for the long post and thanks in advance for any advice you can provide.

 

[alldodge]

Re: Mercruiser 3.0L stalling when adjusting the throttle

Hello All,

I have a 1999 Bayliner Capri 1750 I/O with a Mercruiser 3.0L engine. Ive been having some issues as the boat seems to stall when adjusting the throttle. Im not a very mechanical person but Ive got some good advice on the iboats forum in the past and I would like to attempt to resolve this issue myself before I bring it to the mechanic and break out another thousand. Here is my attempt to best describe the issue:

(Sorry but my RPMs gauge is broken so I can not be specific regarding the exact RPMs)

1) Boat will *generally* start up fine.

2) The boat will generally engage and cruise at a slow no-wake speeds without issue.

3) The boat will generally cruise at a high speed without issue.

4) The boat does not like to cruise at "medium" speed. When adjusting the throttle to medium speed the engine usually either stalls or runs like the engine in this youtube video. (https://www.youtube.com/watch?v=mnkii1E0q1M)

5) Regardless of what speed Im cruising at, adjusting the throttle in either direction (slowing down or speeding up) usually results in the engine stalling.

6) It usually takes a couple minutes and some tinkering with the throttle to get the engine to start and run again.

7) I have noticed that the temperature gauge tends to swing wildly approximately around the times the engine is running poorly, and generally holds steady when the engine is running good. Could this be an electrical issue? Ive had electrical issues in the past.


Sorry for the long post and thanks in advance for any advice you can provide.

View attachment 231859 View attachment 231860

When was the last time the boat had a tune up?
When was the last fuel filter change?
Have you pulled the pugs, and if so what did they look like?

 

[durban131]

Re: Mercruiser 3.0L stalling when adjusting the throttle

When was the last time the boat had a tune up?
When was the last fuel filter change?
Have you pulled the pugs, and if so what did they look like?

I winterized the boat at the end of last year (Nov 2013). I changed the fuel filter as part of the winterization process. I had subtle hints of the stalling issue toward the end of last season and was hopeful that winterizing the boat (which involved changing of the filters) would solve the problem. Which it did not.

I have not pulled the plugs.

 

[alldodge]

Re: Mercruiser 3.0L stalling when adjusting the throttle

I winterized the boat at the end of last year (Nov 2013). I changed the fuel filter as part of the winterization process. I had subtle hints of the stalling issue toward the end of last season and was hopeful that winterizing the boat (which involved changing of the filters) would solve the problem. Which it did not.

I have not pulled the plugs.

You could start with connections. Check them at the battery, starter, block and pull the main harness cannon connector and clean the pins. The weird is OK at idle and high rpm but nothing in between. Also check the shift interrupter and it's switches, be sure everthing is snug.

Are you having any trouble shifting?

 

[durban131]

Re: Mercruiser 3.0L stalling when adjusting the throttle

You could start with connections. Check them at the battery, starter, block and pull the main harness cannon connector and clean the pins. The weird is OK at idle and high rpm but nothing in between. Also check the shift interrupter and it's switches, be sure everthing is snug.

Are you having any trouble shifting?

I dont have any trouble shifting.

Any idea what would cause the issue in this video (https://www.youtube.com/watch?v=mnkii1E0q1M)? My engine sometimes does the same things.

Sounds like a good plan... Ill go over all the connections and make sure all connectors are clean and snug.

 

[alldodge]

Re: Mercruiser 3.0L stalling when adjusting the throttle

I dont have any trouble shifting.

Any idea what would cause the issue in this video (https://www.youtube.com/watch?v=mnkii1E0q1M)? My engine sometimes does the same things.

Sounds like a good plan... Ill go over all the connections and make sure all connectors are clean and snug.

With no other info except the video I would lean toward a fuel carb issue.