2018 Nitro z18.speed problem.

[Kejin]

Hi guys.i have a 2018 z18 with 150 four stroke.Just go out couple times.should be around 10hours around on the motor.didn’t go for the 10hours oil change yet.
when my boat fully load,half tank,with one passenger.the speed only get 40mph.the rpm only 4500.is anything wrong with it?thanks guys

[Nailbender8]

Short answer, yes there is absolutely something wrong with it. Get it to the shop.

[Kerz321]

Yelp. 1000+ rpm short and 20 MPH slow

[Kejin]

I’m thinking.should I bring the boat to dealer this weekend,or after I finish my Sunday tournament? Any suggestions?

[JR19]

A pure guess but it sounds like your throttle linkage is out of adjustment. A Mercury tech can hook a laptop to the boat motor computer and see if the throttle position sensor is reaching 100%. I don't know the exact max rpm for that motor. Someone in another post said you were 1000 rpm low. I think your 1300 low. A Mercury tech can tell you the correct suggested max rpm. Once you get it up to the correct range your speed will see a significant increase.

[Kejin]

A pure guess but it sounds like your throttle linkage is out of adjustment. A Mercury tech can hook a laptop to the boat motor computer and see if the throttle position sensor is reaching 100%. I don't know the exact max rpm for that motor. Someone in another post said you were 1000 rpm low. I think your 1300 low. A Mercury tech can tell you the correct suggested max rpm. Once you get it up to the correct range your speed will see a significant increase.

Thanks.should I bring it to the shop right away?i’m thinking wait for a week.cause I have a tournament this Sunday.

[JR19]

I don't think a couple more trips with 4500 max rpm will hurt. I would want my boat to perform at max or near max performance so I would get it into a dealer sooner rather than later.

Out of curiosity what prop are you running and do you know your prop to pad distance.

[Kejin]

I don't think a couple more trips with 4500 max rpm will hurt. I would want my boat to perform at max or near max performance so I would get it into a dealer sooner rather than later.

Out of curiosity what prop are you running and do you know your prop to pad distance.

Shows up 22p.3 blade.
prop to pad I think is 1.5 to 2 inches

[remaly181]

Shows up 22p.3 blade.
prop to pad I think is 1.5 to 2 inches

You should be running somewhere around 3 1/2". You need to get an accurate measurement. What is your water pressure when you are topped out?

[BearCreek]

boat will only run 4500 rpm but im gonna fish a tournament this Saturday..... Really ?? Take it to the shop dude

[Kejin]

You should be running somewhere around 3 1/2". You need to get an accurate measurement. What is your water pressure when you are topped out?

Ok.where can i find out the water pressure?didn’t see from the dash board.

[C0MRAD]

boat will only run 4500 rpm but im gonna fish a tournament this Saturday..... Really ?? Take it to the shop dude

What's wrong with that? I would make an appointment for early next week and fish the tournament on Saturday.

[JR19]

Ok.where can i find out the water pressure?didn’t see from the dash board.

I would say that a water pressure gauge is very important. I know everyone has their own opinion but I had rather not have a fuel gauge than not have a water pressure gauge because that is how important it is to me. When I took it to the dealer I would ask him some very specific questions.

1. What is the recommended max rpm for your specific motor...a good tech will give you a range something like 5600-5900. In other words they don't want the motor turning more than 5900 but they also want it to turn at least 5600 when the throttle is wide open. I use those numbers as an example. Ask what your specific #'s are.

2. What is the minimum water pressure you should have when running wide open throttle

3. Why do I not have a water pressure gauge and when can you install one...with that being said a water pressure gauge has been standard on boats for several years. I can't even think of a Nitro that does not have one so this leads me to believe you have one but why your overlooking it I have no idea.

4. I would ask them what is recommended prop to pad distance for your specific boat/motor combination and if they will measure and make sure it is set correct. FYI there is no specific number that's good for all boats. Each boat will vary because boats have different motors and different props. Adjusting prop to pad height is like splitting hairs. Sometimes .50" or .75" makes a huge difference. I know a 1/2 inch may not sound like much but it can sometimes make a big difference. The same boat with the same motor might perform totally different at the same motor height with two different props...example a 3 blade prop that is 14.5" in diameter will run better a tad deeper than a 4 blade that is 15.25" in diameter. The 4 blade will run higher because of the extra diameter and extra blade has more resistance so you raise it higher so it spins with less resistance in the water. The 3 blade spins up faster because it has less blades and it's smaller in diameter so you run it a tad deeper so it has more resistance down in the water.

5. I list this a 5 but it would be my #1 question. Is my throttle linkage set so I am obtaining 100% throttle opening at my motor.

When you say you have a 22 pitch prop is it a 3 or 4 blade and do you know what style prop it is. What I mean by that is the prop style a Fury, Tempest, Trophy or some other model.

If you want to measure your prop to pad distance on your own...On concrete or blacktop that is level ground take a 4' level and put it on the lowest part of the boat hull near the rear of the boat (this is called the "pad"). Then crank the trailer jack until the pad is level. You can do this part by yourself but if your laying under the boat with a level it's easier if you have a second person to crank the winch stand while trying to level the pad. Then take a small level and put on the cavitation plate of the motor and trim the motor until the cavitation plate is level. Measure from the LOWEST part of the pad to the ground. Measure from the center of the prop shaft to the ground. This will be dead center of the prop nut. Subtract prop s to ground number from pad to ground number and you have your prop to pad distance...hopefully that makes sense the way I described it.

[remaly181]

Ok.where can i find out the water pressure?didn’t see from the dash board.

Please don't take this the wrong way, but I suggest you get with someone local who can walk you through some of the ins and outs of your boat. Proper motor setup is critical as well as gauge monitoring when operating an outboard. I could be completely wrong, but your woes could simply be just a lack of knowledge and/or experience. We have all been there and you seem genuine in your quest to getting things dialed in properly. I would certainly offer you my phone number via PM if you wanted to just talk through some of the stuff instead of getting a variety of guesses based on limited information. I am not a mechanic, but like many on here, i have been running boats for a while and have encountered my share of gremlins. Most of which were simple fixes.

[JR19]

Please don't take this the wrong way, but I suggest you get with someone local who can walk you through some of the ins and outs of your boat. Proper motor setup is critical as well as gauge monitoring when operating an outboard. I could be completely wrong, but your woes could simply be just a lack of knowledge and/or experience. We have all been there and you seem genuine in your quest to getting things dialed in properly. I would certainly offer you my phone number via PM if you wanted to just talk through some of the stuff instead of getting a variety of guesses based on limited information. I am not a mechanic, but like many on here, i have been running boats for a while and have encountered my share of gremlins. Most of which were simple fixes.

Very well and politely said. I mean no ill will when I say this but it sounds like the OP is not an experienced boater. If this is correct then there is a learning curve WE ALL went through. As remaly181 offered I extend the same offer. If he wants to talk boat/motor shoot me a PM with a phone number I am kind of wondering now if the boat is fully trimmed when only getting 4500. It would be nice to discuss this in person if the OP so desires.

[Silas79]

KEJIN i think what we are looking at here is you where not given a proper walk through and instructions on your new boat. I don't think anything is wrong with it. You need to go back to the dealer you purchased it from and ask the service manager to give you a proper walk through of the gauges and proper operating procedures.

[Kejin]

KEJIN i think what we are looking at here is you where not given a proper walk through and instructions on your new boat. I don't think anything is wrong with it. You need to go back to the dealer you purchased it from and ask the service manager to give you a proper walk through of the gauges and proper operating procedures.

Thanks for the suggestion and all the tips.i called the dealer.i will bring my boat back to them.looks like they didn’t give me all the information I need know for my boat.this my first boat,so always get questions.thanks again

[cubswin]

Are you trimming the motor up when you get on plane? If not the numbers are probably not all that far off.