70 hp evinrude no power at full throttle

[kmacd]

The 70 hp 97 engine starts and idles fine. It will run at wake speed for about 10 minutes {With the throttle on max}then sputter to full power, it may or may not drop back to wake speed.Sometimes after it is running you can pull the throttle back,then push it up and there is no problem. If the choke is applied by pushing the key it will stall out quickly. My experience is, if it was the carbs the choke would push it to full power for a second anyway.

Note, Crabs cleaned.
Temperature switch new
Water pump does not pump well at idle, fine with a little throttle
Engine completely professionally rebuilt two seasons back by number one outboard.
compression 120 in all three cylinders

1997 70 hp 3 cylinders evinrude

 

[zach103]

Re: 70 hp evinrude no power at full throttle

Kind of sounds like your choke is gettting stuck..of something of that nature.. somone with more knowledge will chime in tho

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

Thanks for the response. Choke is ok.

 

[patrick4266]

Re: 70 hp evinrude no power at full throttle

First thing i would do was fix it so it pee's good at idle. It would be ashame to burn a nice motor like that up due to negligence. I have a 1991 70 hp rude. Mine runs great however at full throttle it will surge a little due to something in my gas tank that I will fix over the winter. I'm sure some one will come along with a good answer.

 

[speedracer2j]

Re: 70 hp evinrude no power at full throttle

Had a similar problem in my1985 VRO 70hp, knew fuel pump was good, choke applied engine would rev out. Found fuel line rubber debris in a couple of the main jets. Cleaned them today, and decarboned the engine when I ran it with the mercury can of decarb stuff. Ran GREAT after. Now I am sure fuel lines need replaced to totally eliminate the problem

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

First thing i would do was fix it so it pee's good at idle. It would be ashame to burn a nice motor like that up due to negligence. I have a 1991 70 hp rude. Mine runs great however at full throttle it will surge a little due to something in my gas tank that I will fix over the winter. I'm sure some one will come along with a good answer.

I am going to put a new water pump in asap. I am thinking maybe the temperature switch is more sensitive than I thought.

 

[trendsetter240]

Re: 70 hp evinrude no power at full throttle

The 70 hp 97 engine starts and idles fine. It will run at wake speed for about 10 minutes {With the throttle on max}then sputter to full power, it may or may not drop back to wake speed.Sometimes after it is running you can pull the throttle back,then push it up and there is no problem. If the choke is applied by pushing the key it will stall out quickly. My experience is, if it was the carbs the choke would push it to full power for a second anyway.

Note, Crabs cleaned.
Temperature switch new
Water pump does not pump well at idle, fine with a little throttle
Engine completely professionally rebuilt two seasons back by number one outboard.
compression 120 in all three cylinders

1997 70 hp 3 cylinders evinrude

Sounds a lot like a fuel problem to me. I'd overhaul the carbs again and do a proper link and synch.

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

Are all carb cleaners equal? Can the carbs be cleaned without taking them completely apart

 

[trendsetter240]

Re: 70 hp evinrude no power at full throttle

Are all carb cleaners equal? Can the carbs be cleaned without taking them completely apart

I don't know if they're all equal but I use the standard carb & throttle body cleaner that comes in an aerosol can.

You need to take the carbs apart and spray the cleaner through all the orifices and backwards through the jets. (Backwards meaning the opposite direction of fuel flow.)

Spraying carb cleaner into the carb throat will not clean the jets and fuel inlet.

 

[DJ]

Re: 70 hp evinrude no power at full throttle

You have a clogged high speed jet. Keep running it that way and you will have a melted piston too. Don't ask how I know.

It's time to clean and rebuild all three carburetors.

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

You have a clogged high speed jet. Keep running it that way and you will have a melted piston too. Don't ask how I know.

It's time to clean and rebuild all three carburetors.

Thanx for the tip. I do not have the time to do it myself at this point. I got a price from a dealer, 100.00 dollars a carb labor. Is that price about right? I live in Cape May co.,NJ.

 

[mrcj001]

Re: 70 hp evinrude no power at full throttle

I got a price from a dealer, 100.00 dollars a carb labor. Is that price about right?

If that price includes the carb kits.......

The kits are about 35.00 ea.

It took me about 2 1/2 -3 hours to do the job.....its not that difficult.

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

I decided to take the carbs off today.The inside hardware was in new condition in all three carbs,except for a little oily residue around the high speed jet holes. I made sure the jets were clear and clean. Then reassembled them.The engine idled great. I will run it tomorrow to see if it fixed the problem.
note: I did find cracks in the fuel line as it entered the carbs,I do not think it was leaking but I will replace it.

 

[jeffersondodson561]

Re: 70 hp evinrude no power at full throttle

The 70 hp 97 engine starts and idles fine. It will run at wake speed for about 10 minutes {With the throttle on max}then sputter to full power, it may or may not drop back to wake speed.Sometimes after it is running you can pull the throttle back,then push it up and there is no problem. If the choke is applied by pushing the key it will stall out quickly. My experience is, if it was the carbs the choke would push it to full power for a second anyway.

Note, Crabs cleaned.
Temperature switch new
Water pump does not pump well at idle, fine with a little throttle
Engine completely professionally rebuilt two seasons back by number one outboard.
compression 120 in all three cylinders

1997 70 hp 3 cylinders evinrude

Float level on carbs?
Is the enrichener manual (red) valve cracked?

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

Well the carb clean and inspection made no difference, no power at full throttle. I rechecked the spark it was ok, at idle anyway. I rechecked the fuel for water,no water. The engine will now quit at idle without a little extra throttle. It will also throttle up in neutral but not in gear.

The inside of the carbs appeared fine no clogs no cracks, matter of fact they looked in new condition.

Would a bad power pack cause this?

The only red valve I see is the choke,it looks fine.

 

[kmacd]

Re: 70 hp evinrude no power at full throttle

Problem solved.

I assumed" the compression was good , as I had just taken a compression check the day before I had the problem and found 120 in all cylinders. However, today I hired a mechanic, he check the compression and found only 15 pounds in the top cylinder. It had a blown head gasket, no visible signs of damage to the cylinder. The engine is back in running condition with full power at wide open throttle.

A Thank you to all that contributed,

looking like a Dummy

 

[Bosunsmate]

It's an older post but just came across it after searching because I just started experiencing same issue. A new boat to me, the maiden voyage was running great then lost power at full throttle. When i throttle down and open it up again, it surges for half a second then loses power again. If I hit choke, it also surges after a few seconds then loses power again. I haven't checked yet but almost positive it's trash in fuel system, probably in carb. I am going check filter in the next few days and if I see evidence of trashy gonna remove and clean carbs. The only thing that makes me thing I could be something else is when i disengage prop and throttle up, it doesn't lose power or sputter but of course it's not under load. Hopefully it's a quick fix though.. Btw it's a 2000 Palm beach 161 with a 70 HP Johnson.

You should start a new thread. Theres a link on the left near the top of the main john/evinrude page to click
In the meantime, It could be a few things but start on carbs, then fuel pump