2010 Tahoe Q5i 4.3l will only make 3500-3700 rpm, 32 mph

[ohaze]

Ohaze,
Do you have any idea how many hours may be on the engine? Have you done any compression testing? Simple to do and may provide some insight into the problem. Just out of curiosity, where are you located?

No exact count but expect they are on the low end. The couple I bought it from only used it on a small lake and probably never hit WOT much if at all. The engine is very clean, and seems to have been well maintained by a Tracker service center (I have all the receipts from original owners) . That is part of what's puzzling me, I highly doubt this is the issue but could the hours be low enough it may still be in break in? I have not done or had a compression check yet that will be one of my first checks when I get back from Vaca. Boat is running fine here, just not making all the power it should.

 

[BCran]

No exact count but expect they are on the low end. The couple I bought it from only used it on a small lake and probably never hit WOT much if at all. The engine is very clean, and seems to have been well maintained by a Tracker service center (I have all the receipts from original owners) . That is part of what's puzzling me, I highly doubt this is the issue but could the hours be low enough it may still be in break in? I have not done or had a compression check yet that will be one of my first checks when I get back from Vaca. Boat is running fine here, just not making all the power it should.

I don’t think it has anything to do with break-in on a 13 year old engine. I also looked up what happens when you spin a hub, and you would get higher rpm and reduced power, so I don’t think it’s the prop hub.

You didn't answer my question about your location. Are you at high altitude or was the boat previously moved significantly in elevation? If so, it could be a carb jet issue.

Does the engine seem to hesitate, surge or misfire when you accelerate? If so, I would change the fuel water separator, dump the contents into a jar and see if there is any sediment or water in the fuel. If so, take a look into the gas tank. Try running carb cleaner through then next tanks full of fuel and see if you experience any improved performance. I’ve used various brands of carb cleaner but have several friends who swear by “seafoam” for their boats. I also run Stabil 360 Marine in all my fuel to counter the effects of ethanol.

It may be time for a full tune up, plugs, wires, cap, rotor and even a carb rebuild. If the boat sat idle a lot, then the carb may be the issue. It could have a bad accelerator pump in the carb. Previous owner(s) may not have been using Stabil during the off season and allowed the carb to gunk up. (Yes, Gunk is a technical term). I’m in Indian Land, SC not to far from Charlotte, NC. If you’re nearby, let’s put the boats side by side and see how they compare. Im leaning toward this being a fuel/carb problem. That boat with 4.3L TKS should be making the same RPM (4800) and speed (55) as mine with the 14x23P prop.

BC

 

[ohaze]

I don’t think it has anything to do with break-in on a 13 year old engine. I also looked up what happens when you spin a hub, and you would get higher rpm and reduced power, so I don’t think it’s the prop hub.

You didn't answer my question about your location. Are you at high altitude or was the boat previously moved significantly in elevation? If so, it could be a carb jet issue.

Does the engine seem to hesitate, surge or misfire when you accelerate? If so, I would change the fuel water separator, dump the contents into a jar and see if there is any sediment or water in the fuel. If so, take a look into the gas tank. Try running carb cleaner through then next tanks full of fuel and see if you experience any improved performance. I’ve used various brands of carb cleaner but have several friends who swear by “seafoam” for their boats. I also run Stabil 360 Marine in all my fuel to counter the effects of ethanol.

It may be time for a full tune up, plugs, wires, cap, rotor and even a carb rebuild. If the boat sat idle a lot, then the carb may be the issue. It could have a bad accelerator pump in the carb. Previous owner(s) may not have been using Stabil during the off season and allowed the carb to gunk up. (Yes, Gunk is a technical term). I’m in Indian Land, SC not to far from Charlotte, NC. If you’re nearby, let’s put the boats side by side and see how they compare. Im leaning toward this being a fuel/carb problem. That boat with 4.3L TKS should be making the same RPM (4800) and speed (55) as mine with the 14x23P prop.
View attachment 384193
BC

Thanks, no owner and I both live in the St. Louis, MO area so no altitude change. I'm leaning heavily on the fuel/carb side that you mentioned. From my understanding the boat sat for at least a year and probably longer. Owner mentioned Stabil always added prior to storage and when I got it there was only a 1/4 tank of gas in it (not filled prior to storage from what I could see). Makes sense on the spun hub higher rev point you mentioned. I did notice the day I was switching hubs and it started running a bit better that when idling out in totally flat water I could feel a slight surge of power every once in a while - which with what you've mentioned is making me think there is a good chance there is fuel/carb/Gunk issue going on. It seems to be getting a little better each time I go out so whatever (carb passage maybe) is trying to work itself out. If I can get my hands on some Seafoam while I'm here I will try that. Else when I get back I'll get a full tune up service done. Thanks again!

 

[ohaze]

Also once the tune up/rpms are done and seems to be more in line with normal operation I'll be getting another prop (or two) and be looking at those recommendations as well. Thanks folks, really appreciate the help here and I'll definitely reply back once I get it all straightened out.

 

[BCran]

Also once the tune up/rpms are done and seems to be more in line with normal operation I'll be getting another prop (or two) and be looking at those recommendations as well. Thanks folks, really appreciate the help here and I'll definitely reply back once I get it all straightened out.

Once it’s tuned up, I think you’ll be happy with the stock aluminum 14x23P. But let me know what you learn while playing with all the props. I want to put a SS prop on mine and keep the alum 23P as a back up. I believe that I need to drop down to a 21P if I go to SS.
Good luck!!
BC

 

[QBhoy]

Hi. Thought I’d add to the mix. Make sure that enrichment system those tks have, isn’t playing up. Known to cause issues for sure.

 

[BCran]

Once it’s tuned up, I think you’ll be happy with the stock aluminum 14x23P. But let me know what you learn while playing with all the props. I want to put a SS prop on mine and keep the alum 23P as a back up. I believe that I need to drop down to a 21P if I go to SS.
Good luck!!
BC

Ohaze,
This is my 2011 Q5i 4.3 TKS from a dead stop, idling at 650 rpm, trim down. This is with the stock 23P Alum prop. The site doesn’t allow for long videos but you’ll see that it come out of the hole, planes and runs right up to 54. I could squeeze a little more out of it but with one hand on the wheel and one on the throttle and one on the camera and a thump on the trim, it was a little sketchy. But you get the idea. That’s how yours should be running.
BC

 

[ohaze]

Ohaze,
This is my 2011 Q5i 4.3 TKS from a dead stop, idling at 650 rpm, trim down. This is with the stock 23P Alum prop. The site doesn’t allow for long videos but you’ll see that it come out of the hole, planes and runs right up to 54. I could squeeze a little more out of it but with one hand on the wheel and one on the throttle and one on the camera and a thump on the trim, it was a little sketchy. But you get the idea. That’s how yours should be running.
BC

I realize its been a bit bit thanks for that video! That really showed me how this boat/motor should be running. Happy to say I have it running the same now! Did a full tune up (dist cap,rotor,plugs, wires,fuel/water sep) and runs great, revs full now. The biggest and most obvious was the distributor cap, every plug contact (firing contact) had green oxidized gunk built up, rotor I literally had to pry off - must have been original. All plugs brown with some oil/gas buildup but not terrible. In the end, I think it was that distributor cap and rotor causing all the issues - weak fire Thanks again for all the ideas and help!

 

[BCran]

No exact count but expect they are on the low end. The couple I bought it from only used it on a small lake and probably never hit WOT much if at all. The engine is very clean, and seems to have been well maintained by a Tracker service center (I have all the receipts from original owners) . That is part of what's puzzling me, I highly doubt this is the issue but could the hours be low enough it may still be in break in? I have not done or had a compression check yet that will be one of my first checks when I get back from Vaca. Boat is running fine here, just not making all the power it should.

I realize its been a bit bit thanks for that video! That really showed me how this boat/motor should be running. Happy to say I have it running the same now! Did a full tune up (dist cap,rotor,plugs, wires,fuel/water sep) and runs great, revs full now. The biggest and most obvious was the distributor cap, every plug contact (firing contact) had green oxidized gunk built up, rotor I literally had to pry off - must have been original. All plugs brown with some oil/gas buildup but not terrible. In the end, I think it was that distributor cap and rotor causing all the issues - weak fire Thanks again for all the ideas and help!

That boat/motor/prop combo performs very well when it’s running right. I’m glad you got it running like it should. I’ll bet you’re going to keep that 23p prop on it too.
Take care and enjoy your “new” boat.
B