1988 Yamaha 25

[rocker3]

Hello<br />I have a 88 25 hp Yamaha. Its has oil injection. It runs great until it warms up then it loses power. It stays running but no power. The red light in on like its hot but it don't feel hot. Sit for 10 min. and it runs great untill it warms up. Nobody can tell me what wrong. Thanks

 

[rocker3]

Re: 1988 Yamaha 25

So nobody has an idea? Ok its a 1988 25 hp Yamaha,model 25SG. Like I said it runs great untill it warms up,then loses power and cuts out. I don't have a manual for it but I think the red light means it hot or out of oil. I can put my hand on the head and its not hot. Water pump is working. It don't seem to use very much oil but the oil goes down a little in the tank. I run it today but I put oil in the gas but its run the same. Could a coil be heating up and breaking down? the power pack going bad? Someone please reply. Thanks

 

[clanton]

Re: 1988 Yamaha 25

The first thing I would do is find out what the red light is for and repair what is turning the light on. I dont have any Yamaha manuals or work on them, so not much help.

 

[Ray Neudecker]

Re: 1988 Yamaha 25

First check compression. light will go off if a head gasket is leaking and increasing combustion chamber temp. Your running problem could also be a fuel restriction. If you plan to repair yourself, you really need a service manual. But the very first thing I would do is check compression.

 

[nodima]

Re: 1988 Yamaha 25

I am having similar issues with my 1993 Yamaha 25, just posted last night my specific issues. How recently have you replaced the impeller/T-stat? <br /><br />The red light can be either and oil or heat issue. The manual has some info on how to check the function of the oil sensor <br /><br />good luck, and please post results of the issue.<br /><br />nodima

 

[rocker3]

Re: 1988 Yamaha 25

First I'll like to say I'm sorry for the other post. I had hoped that someone would reply sooner. Here at home we can only run our 25's when the river is up,and its up now. I took it to a marina last year and they didn't know why the red light was on. They let it run in the tank for an hour and it wouldn't mess up. I have never replaced the impeller. I'm going to take it to a friends and check the compression. Again sorry and thanks. Jim(rocker)

 

[Ray Neudecker]

Re: 1988 Yamaha 25

Those things will frustrate you. If you and your friend are going to troubleshoot yourself, post what you find as you go along. There is plenty of good help here, but the problem is not clear enough to give instant answers. Problems such as this are repaired by doing a process of tests. You can have more than one problem or repair to make before you are done. Most problems on those motors are basic, many times normal service issues. They have been extremly reliable and had no real recurring problems. The people on this and most message boards are friends trying to help and learn from each other. No one understands boater fever any more than I do. Hope this helps.

 

[rocker3]

Re: 1988 Yamaha 25

On the red light. Its only on when you give it gas. You run it wide open the light is fickering and when it starts messing up the red light is just on. Friend wasn't home so don't know about compression. Thanks again

 

[Ray Neudecker]

Re: 1988 Yamaha 25

The light is a warning. When you get the problem fixed, it will likely go out. Since you have run the motor with extra oil and not changed the symptoms, it would point to heat related. If the head is not hot, then you have to check for an internal problem. Good Luck, gone racing. Check on you the first of the week.

 

[rocker3]

Re: 1988 Yamaha 25

Haven't got compression check done,buddy was in a car wreck. Went to the river this weekend(I know I shouldn't be running my outboard like it is, but couldn't help it,got the boating fever bad LOL and the river is going back down too) and it ran the same. Was looking at the motor and there is some oil coming from under the magneto. Is there a gasket under it that might be leaking? Thanks for any idea's on this.

 

[Ray Neudecker]

Re: 1988 Yamaha 25

There is a seal there for the crankshaft.

 

[rocker3]

Re: 1988 Yamaha 25

Could that be the problem?

 

[Ray Neudecker]

Re: 1988 Yamaha 25

You are going to have to act like you were working in a shop and do the basic trouble shooting such as checking compression,ect. before finding the problem. Many times the participants on the board because of experience can put you on the right path and sometimes even offer a quick easy solution. As you can see from some of the posts, this is not always so. This is also why the shops and mechanics can be so vague when discussing what may need to be done to correct your problem before actually having a chance to test the motor.

 

[rocker3]

Re: 1988 Yamaha 25

Hey I'm back. Checked compression,over 100 in each. Going to change oil seal on top of crankshaft this weekend. Maybe thats the problem. Got some used coils off of a 40hp yamaha,not sure what year.Coils don't look the same but bolt pattern is the same.Will the coils work on the 25hp? Thanks

 

[new2obrepair]

Re: 1988 Yamaha 25

change the impeller, check the thermostat in boiling water. change if neccessary.<br /><br />Ny of you guys read my last post? I am getting zero replies for 2 days? Something wrong with my posts?

 

[rocker3]

Re: 1988 Yamaha 25

Well since no one knew if the coils would work on a 25,they will. Got the red light out. Had a short in one of the wires to the light. With the light out it runs better but after 5 to 10 min it starts cutting in and out but not as bad as it did.I can still plain the boat. <br />Heres what we did.<br />tried the coils -didn't help<br />changed the oil seal and got all the oil off of the magneto. didn't help<br />Tried another tank and hose-didn't help<br />adj. on carburetor and ran carburetor cleaner though it-didn't help<br />It has new spark plugs<br />Ok guys,don't leave me hangen here. Got any idea's? Thanks

 

[Ray Neudecker]

Re: 1988 Yamaha 25

Take the carb apart and thourghly clean. Need to soak in carb cleaner and rebuild.

 

[rocker3]

Re: 1988 Yamaha 25

Ok will do the carbs. Question,if its in the fuel then why don't it do when I start it? Why does it wait 5 to 10 min? Thanks. Ray what kind of boats do you race?

 

[Ray Neudecker]

Re: 1988 Yamaha 25

What little actual racing I do now is in a drag boat. Allison Bass Boat with a Yamaha in the 10 second bracket. I raced roundy round in tunnels and v-bottoms for a number of years, also river races in Allisons. Mostly build motors and crew chief for others now.

 

[rocker3]

Re: 1988 Yamaha 25

Hello<br />Help...running out of money on this motor. Had carburetors rebuild,fuel pump rebuild.($280.00)<br />new coil($80.00)only got 1 and switched it around.New cdi($280.00) New tank line. The motor still runs great for 5 to 10 min then loses power. Let it sit for 5 min and off you go. Any idea's? Can't afford to put much more money in it. Thanks <br />1988 25 hp Yamaha