Slow Speed at Full Throttle

[rjehmiller]

I just purchased a 1986 40 HP Evinrude and got it out on the lake my self for the 1st time.

40 HP Problems:

1. I opened it up to full throttle and The boat speed would only reach 105. MPH. I let it run for about 200 feet this way and it never picked up.
2. Does not idle in gear at slow speed.
3. Has a little troble to stay running when cold.


The motor is on a 1986 Lund Rebel. i also have 8 horse Evinrude on the same boat and it only gets up to a speed of 55. MPH (this seemd normal.

8 HP Problems:

1. It reves really high then back down then dies (when cold).
2. Does not idle in gear at slow speed.
3. Has a little trouble to stay running when cold.

I am thinking bad gas (it is about 2 months old) or bad carberator adjustment.

Please advise..

 

[DJ]

Re: Slow Speed at Full Throttle

105 MPH? I want that 40.

55 MPH? I also want that 8.

My best advice is that you have fouled fuel and fouled carburetors.

Both require complete carb disassembly and cleaning and reassembled with NEW kits. As a starting point.

Don't forget the water pumps, while you're at it.

Buy a manual, available here on iboats for about $30.00.

You may find one that covers both.

 

[tashasdaddy]

Re: Slow Speed at Full Throttle

i think you need to rephrase your speed 105 mph is impossible with 40, as 55mph is with an 8. is this motor new to you, has it done this since you had it, or did it just start. have the motors been setting up for a period of time? what year is the 8 hp. suggest splitiing your post 1 for the 8 and one for the 40, so they stay straight, can't talk about 2 motors in same post. click boat forums, at the top of the page, then engine faq, read awakening a sleeping outboard. as i said start new post for the separate the engines.

 

[rjehmiller]

Re: Slow Speed at Full Throttle

Sorry the I forgot the . the rateing should be 10.5 MPH for the 40 HP and the 5.5 MPH for the 8 HP.

I just purchased a 1986 40 HP Evinrude and got it out on the lake my self for the 1st time.

40 HP Problems:

1. I opened it up to full throttle and The boat speed would only reach 105. MPH. I let it run for about 200 feet this way and it never picked up.
2. Does not idle in gear at slow speed.
3. Has a little troble to stay running when cold.


The motor is on a 1986 Lund Rebel. i also have 8 horse Evinrude on the same boat and it only gets up to a speed of 55. MPH (this seemd normal.

8 HP Problems:

1. It reves really high then back down then dies (when cold).
2. Does not idle in gear at slow speed.
3. Has a little trouble to stay running when cold.

I am thinking bad gas (it is about 2 months old) or bad carberator adjustment.

Please advise..

 

[rjehmiller]

Re: Slow Speed at Full Throttle

Make this post the 40HP post. I will post for the 8 HP later.

I just bought the boat and this is the first time I had it on the water.
Yes the motor and gas have been sitting for a while about 2 months.

 

[iwombat]

Re: Slow Speed at Full Throttle

Sounds to me like you might be missing on one cylinder. Start by putting in fresh plugs and go from there.

 

[tashasdaddy]

Re: Slow Speed at Full Throttle

start with a compression check on the 40 before you spend any money. remove plugs, disconnect gas line, put in forward, full throttle, now you will have to jump the starter solenoid to turn it over.. insert gauge, turn over for 4 revolutions, record reading and cyl # do this for all cylinders. now put back in neutral and check for spark, should be blue and jump 7/16 of an inch,, you can get a spark tester, at auto part store or walmart for $10,00. post the results. this tells us the health of the engne. then we go from there.

 

[rjehmiller]

Re: Slow Speed at Full Throttle

Thank you for all the help the problem is fixed.

Last night I checked the spark before changing out the gas. I had good spark. So I picked up a can of Sea Foam, New two cycle oil for outboards, and 92 prebium() octane gas. I got it out on the water and as soon as all the old gas was out and then new gas hit the pistons (I had the throttle opened all the way) the boat about threw me across the lake. Again thank you.