Logo
FULL SITE MENU

Out board motor not running up to power

N

neighborbill

Member
I've got a fourwinns 170 Freedom with a 115 Johnson outboard on it 2 stroke. Both from 1995. Over the last couple of years the motor would lose power for what seemed like no reason. And then it would kick back in and everything was fine. This year I took it out and from the start I could only get the rpm's and hense the speed up maybe half of what it should do. It has always been hard to start, but this power problem is fairly new. It feels like there is a gas feed problem. I change the filter, and put new premium gas in but that didn't help.
It's hard to do anything on the motor when it is on the trailer. Water muffs work for idle and starting but you can't run full throttle with that set up.
Looking for some ideas before i have to take it in for repairs.

Bill
 
These motors are not hard to start at all.-Are you raising the throttle only lever ?------Are you pushing the key in while cranking the motor over ?-----------------Does it run any better with the cowling off ?------------These motors do have a history with compression problems and broken piston rings.----Just picked up a 1995 model myself to rebuild for that same reason.
 
racerone said:
These motors are not hard to start at all.-Are you raising the throttle only lever ?------Are you pushing the key in while cranking the motor over ?-----------------Does it run any better with the cowling off ?------------These motors do have a history with compression problems and broken piston rings.----Just picked up a 1995 model myself to rebuild for that same reason.
Click to expand...

I'm really not concerned about the starting problem as much as the full throttle problem. Sometimes it runs at 35 mph where it always did with max RPM's. It ran with no problems last year a couple of times, but every once in a while it would just cut back like someone pulled the accelerator back. It would run that way for a while and kick in again to high speed. This year I could not get it up to full throttle acceleration. It is like it isn't getting the gas that it needs. LIke a blocked filter. But, the filter is new.
 
One more try.--2 simple tests that cost no $.----Run with a timing light and see if you have issues with spark.-Hook up to each plug for a while.----Remove cover in front of carburetors and use a STRONG flashlight to shine in each bore.---Compare fuel coming up the main nozzle of each carburetor.------No need to mention that these tests are to be done out on open water I hope.
 
racerone said:
One more try.--2 simple tests that cost no $.----Run with a timing light and see if you have issues with spark.-Hook up to each plug for a while.----Remove cover in front of carburetors and use a STRONG flashlight to shine in each bore.---Compare fuel coming up the main nozzle of each carburetor.------No need to mention that these tests are to be done out on open water I hope.
Click to expand...

Ok this would be worth trying. I rev up the motor yesterday in neutral. No problems getting up the RPM. However, the day before when I had it under load in the water it would not rev up. Is there something that happens under load that doesn't happen when there is no load?
 
Winding it up in nuetral means nothing at all.-----The motor would wind up running on 2 of 4 cylinders .----Not sure why folks can not grasp this concept !!!
 
racerone said:
Winding it up in nuetral means nothing at all.-----The motor would wind up running on 2 of 4 cylinders .----Not sure why folks can not grasp this concept !!!
Click to expand...

Not sure what your point is. "Winding it up in nuetral means nothing at all" A more constructive comment in stead of " Not sure why folks can not grasp this concept !!!" would be appreciated. I think people write to this board looking for help not waiting for comments like yours.
 
kimcrwbr1 said:
Other than the load. So far all you have done is change gas and a filter from what I am reading. The hard cold start issue can very well be related. How often do you change the gearoil and spark plugs? You need to do a proper diagnostic check compressin and spark gap with a spark gap tester. The compression must be even and the spark must jump a gap of at least 7/16 inch brite blue snap. Get back with the compression numbers engine cold.
Click to expand...

I've changed the gear oil at the end of every season and the spark plugs are new every year, needed or not. I have yet to check compression but I don't know why the boat would run good sometimes with bad compression. One would think that this would be a constant problem with bad compression. Never the less, it's worth looking at.
Thanks.
 
neighborbill said:
Ok this would be worth trying. I rev up the motor yesterday in neutral. No problems getting up the RPM. However, the day before when I had it under load in the water it would not rev up. Is there something that happens under load that doesn't happen when there is no load?
Click to expand...

Yes, your propeller turns. Your engine may not have a rev limiter, but mine does, and with a bent prop your engine can overrev. This causes the limiter to cut the engine back until it is safe. Then it will pickup power again, until it overrevs again. It acts just like you threw the choke on it. Next time on the water and it happens, pull throttle back to half, and when it picks back up go to about 90 percent throttle and see if it continue to run.
 
kimcrwbr1 said:
It is bad for the motor running it at high rpms without a load because it takes alot less fuel to run faster. Engine oil is in the fuel so revving it up without a load is like running your car after draining the oil out. Besides running the prop fast out of the water can damage it also. When troubleshooting a motor allways start with compression and spark gap. It is very common for guys to go directly to fuel for performance issues and you need good compression and spark to burn the fuel so eliminate the variables. Pull all the connectors apart and clean with electrical cleaner. Put back together with dielectric grease and push all the pins in on both sides with a jewelers screwdriver. Sand all grounds metal to metal including components that use the mount bolt for a ground. Inspect the wires good looking for bare, cracked, broken wires and fix as necessary, Be careful running it like it is you may need the carbs rebuilt make sure the engine is mechanically sound then you can focus on fuel delivery.
Click to expand...

Good advice all the way around. I've never rev'd and kept it there. Just wanted to see if it would go. I have the motor prop in a large tank of water (90 gallon feed tank). Never the less, I agree with needing less gas to get high rpm.

I'll be taking it in on Monday to someone who might know more about it then I.

Now I'm starting to think about replacing with a 4 stroke. But, it looks like a nightmare to substitute with cables and wiring.
 
Back
Top