Motor run up on trailer

[mauzy]

I have a 1981 75 hp evinrude. Should I be able to run the motor up to full throttle in gear with it on the trailer in the water. My motor dies at about 3000 rpms.

 

[Franki]

Re: Motor run up on trailer

sure you can, just keep in mind, "for every action there is an equal and opposite reaction"<br /><br />you will put alot of force onto your trailer when you do that.. also alot more on your transom since the force won't be taken up by forward motion.<br /><br />I wouldn't do it unless you had no other recourse..<br /><br />Also, your motor will be unlikely to reach WOT on the trailer and you could damage your motor through overloading..<br /><br />if you want WOT, put the boat in the water, (off the trailer)<br /><br />regards<br /><br />Frank

 

[mauzy]

Re: Motor run up on trailer

Ok but way is my motor dieing at 2000 to 3000 rpms. I know you haven’t even seen my motor but can you give me things to look for. Some things I can think of are prop size and compression. Is there a place on the net for sizing props and finding compression specs.

 

[mauzy]

Re: Motor run up on trailer

What is WOT,

 

[FlyBoyMark]

Re: Motor run up on trailer

The motor shuld not die though...sounds like a lean carb condition....take apart, clean, new kit, adjust to spec after assembly.....

 

[petryshyn]

Re: Motor run up on trailer

Many things can cause low power.....<br />check the simple ones first, you could get lucky!<br /><br />>fuel supply....squeeze the primer bulb hard, does it help?<br />>do you have good spark to all plugs?<br />>have the plugs been changed?<br />>have the carbs been cleaned recently?<br />>is the compression OK (relatively even)?

 

[mauzy]

Re: Motor run up on trailer

It’s a 1981 75 hp rude. Three carbs. Is cleaning and adjusting the mixture a hard job?

 

[Boatist]

Re: Motor run up on trailer

I do not understand why you would want to do that. It is dangerous, could wreck your boat, motor, trailer, and your truck. I guess if you are going use it as a tug might make sinse. Kind of like a tractor pull you are straining everything. Motor is designed to reach a certain RPM at Wide Open Throttle (WOT) (Full Throttle) on your boat moving thru the water. On the water your boat picks up speed which helps suck exhaust out of prop so you do not build a lot of back pressure. When you go home put your truck against a tree and stick a Patatoe in exhaust and do full throttle may get same results. You select prop with your boat on the water at full throttle then you check the rpm to see if it is in right range for your motor. You can not pick a prop with boat stopped in water. On the trailer you could spin the hub in the prop, break a gear or twist the drive shaft. Main thing here is motor is not designed to run that way and if you got it to run it best that way then took it out on the water you would have to start over. Good luck and stay safe.

 

[Down South]

Re: Motor run up on trailer

Your motor Should not Die doing this, but also keep in mind tha your motor will not go to full RPM. It will appear to bog down. I've done tis a few times when I didn't get my trailer far enough in the water to load the boat all the way on the trailer. If it dies doing this then you have a problem, probably in the fuel system. (By the way, I've used my motor to help get my trucK out of the launch ramp when it was muddy and the truck wouldn't pull it out on it's own)<br />Good luck...

 

[johnkc]

Re: Motor run up on trailer

if you are leaving the boat on the trailer, and putting the engine in gear,then advancing the throttle thus putting a load on the engine, aren't you using the lake as a back in test tank???