Slow Starting Mercruiser 5.0

[drcalderwood]

I have a 2000 19' Rinker open bow with the 5.0 merc and Alpha one drive. It has a problem with getting up to full power until it has been running/idling for about 5-10 minutes. If I start it up and then try to accelerate, it bogs down at around 10 mph and can't go any faster regardless of how much throttle I give it. It's not so much a problem when I first take it to the lake because I can keep it running while I am parking the truck and trailer and then I can keep it warming up while I work my way out of the marina and wakeless area. It's the biggest hassle though when I am camped at the lake and want to get up and go water skiing at first sunlight. Sometimes it has to be at operating temp for a few minutes before it seems to go away.
Once it's warmed up and gotten to the point that it runs smoothly, it no longer is an issue. I can stop it and turn it off for a while, then start it back up with no issues. It's only associated with the cold start. Is there anything I can fix or do to improve that performance, or do I just need to be patient everytime I cold start it and give it 10 minutes?

 

[Scott Danforth]

It is common to require the motor to warm up on I/O's. however have you checked your choke settings recently?

 

[alldodge]

I have a 2000 19' Rinker open bow with the 5.0 merc and Alpha one drive. It has a problem with getting up to full power until it has been running/idling for about 5-10 minutes. If I start it up and then try to accelerate, it bogs down at around 10 mph and can't go any faster regardless of how much throttle I give it. It's not so much a problem when I first take it to the lake because I can keep it running while I am parking the truck and trailer and then I can keep it warming up while I work my way out of the marina and wakeless area. It's the biggest hassle though when I am camped at the lake and want to get up and go water skiing at first sunlight. Sometimes it has to be at operating temp for a few minutes before it seems to go away.
Once it's warmed up and gotten to the point that it runs smoothly, it no longer is an issue. I can stop it and turn it off for a while, then start it back up with no issues. It's only associated with the cold start. Is there anything I can fix or do to improve that performance, or do I just need to be patient everytime I cold start it and give it 10 minutes?

:welcome: to iboats

Would you know your engine serial number?

 

[DaveG55]

Yep, more information on your engine is needed. For instance, is it carbed or injected? Im sure the sn will tell the gurus exactly what you have though.

 

[Bondo]

Ayuh,..... Get outa bed 5 or 10 minutes sooner,......

 

[NHGuy]

I bet you have a carbureted engine with a sticky choke. If you do here are some things you can do before really tearing into it.
The first thing is to remove the spark arrestor from the top of the carb. Stick your finger in the lower side of the choke plate and see if it snaps closed when you let it go. If it's a little sticky you can exercise it a little to try and get it free. If it's stuck hard don't force it.

Check out your choke pulloff system. You should find a round device on the end of the choke shaft with a wire to it. That's your electric choke pulloff. Make sure the contact with the electric plug is good. Remove the connector, check for and clean up corrosion, and plug it back in. If you have a test light or meter, check that it has power with the key on. It could also need adjusting to a more open position, so it opens the choke earlier as the motor warms. When cold it should just barely close the choke.

Get the motor running around 900 or 1000 rpm with the spark arrestor off and watch to see how the choke opens. If the choke is sticky shoot some bursts of carb cleaner around the linkage that's on the side opposite from the throttle cable. The choke links and pulloff will be over there. Don't send a steady stream of cleaner, that can overload the engine and stall it or flood it. And don't be surprised when the engine changes speed with using carb cleaner. The motor will come back to it's original speed momentarily.
After it's begun to warm, or fully warm, running at 1000 to maybe 1300 you can shoot some bursts right into the carburetor top choke area to clean up in there.

If the choke and linkages were already OK or if the above steps do nothing you might have other issues. Or if the choke links to a metal coil on top of the intake, let us know. That's an earlier system like I have.