Logo
FULL SITE MENU

2000 Johnson 25hp 3 cylinder seems slow.

J

JeepNWilly

New member
Hi I am new here and also new to boating in general. I recently bought a 16 foot Sundance Skiff with a 2000 Johnson 25 hp 3 Cylinder. Engine starts and runs good. there are time it shuts off when idling after it has warmed up.
1st question - What should the RPM be during idle?

2nd question - I seem to only get 10 mph (per hummingbird depth finder) when I have 4 people on board. Won't get on a plane.
The RPM at full throttle was 4200. Being that it is a 3 cylinder shouldn't it go faster?
 
you can try messing with the trim. That is a small boat to have that many people. I see that the boat is rate a 40 to 50hp so it would do a lot better with that size motor. You also have to make sure you have the boat loaded right to get it on a plane.
 
Mattl468 said:
you can try messing with the trim. That is a small boat to have that many people. I see that the boat is rate a 40 to 50hp so it would do a lot better with that size motor. You also have to make sure you have the boat loaded right to get it on a plane.
Click to expand...

I have played with the trip but the best I get is 10/11 mph at 4200 RPM full throttle
 
faztbullet said:
Under powered !!!!
Click to expand...

I figured 25hp was a bit low but the was hoping to be able to give it a little boost for the few times I load it up and head to the sandbar.

Again I am new at this but what is kinda strange to me no knowing much about outboards is seeing other with higher hp (40) be physically the same size as my 25 hp.
 
Is oil injection in service , yes or no ?--------------Do a compression test.----------Check for spark on all 3 leads.----May be running on 2 of 3 cylinders.
 
racerone said:
Hopefully the oil injection was thrown away before damage was done !---Do a compression test on it.
Click to expand...

The original owner was the grandfather of a good friend of mine. I was told that he removed it as soon as he got it.

I can do a compression test. Do you know what the readings should be?
 
I personally don't think there is anything wrong with the motor. I think you have it under powered and overloaded. How does it run with 2 people?
 
I have only had it for a few weeks and only used it 3 times so far. The first run was on a lake with my son and daughter. I was able to get it on a plane at times but not always. When on plane it did 15mph (per hummingbird depth finder) but also on the same ride there were times it only did 13mph. Would there be a difference in performance on Saltwater vs fresh water?

I did take a look at the 3 blade prop and it looks a bit rough on the leading edge of the blades. Trying to determine the spec on it to replace it but was also wondering if I should attempt to file down the leading edge to get it sharp and smooth as a test.

There is a spare 4 blade prop in the boat but haven't tried it yet. It look older but the leading edges look a lot better. I am thinking at some point the previous owner switched from a 4 blade to a 3 blade.
 
Anyone have any ideas on the idle question I had in the original post?

Basically after engine is warm it won't idle in gear or in neutral for very long. At home with hose no issues with idle at all.
 
"1st question - What should the RPM be during idle?"
Per the manual, 'engine idle speeds in gear range from 700 to 800 RPM, depending on propeller selection.'
I would suggest you get the manual for your specific year; they are cheap on ebay and offer a wealth of info.

Those were also great engines, albeit with a few quirks. The mixing unit was the biggest, and it seems you have yours removed and pre-mix (good).
Second were the powerpacks, but you have other items to check first (namely, the compression test as mentioned above) and then the spark gap.

Those engines' full operating range is 5200-5800 RPM, so you are definitely lugging that engine. They were designed around the 4 blade prop. Standard is either 10.5" x 12" or 10.5" x 14". It will be marked on the side of the prop. Make sure you running correct Champion spark plus too (not NGK or something else). Specific plugs were called for by engine year, but typically QL86C (1996-1998) or QL82C (1998 on).
 
Thanks for that great info. Yea I will look into getting a manual soon.

This weekend I will run a compression test on it. I will also take a look at the spark plugs tonight there are 4 spares in the dry box where I have the boat registration papers etc.. With regards to the prop I have looked all over it and no luck finding any numbers. The black paint is chipping off on the blades. I will take another look at both the 4 blade and the 3 blade for numbers.

I am attaching pics of the boat.

Resized_20170611_175924.jpgResized_20170626_145533.jpg
 
NautiBuoys said:
Those engines' full operating range is 5200-5800 RPM, so you are definitely lugging that engine. They were designed around the 4 blade prop. Standard is either 10.5" x 12" or 10.5" x 14". It will be marked on the side of the prop. Make sure you running correct Champion spark plus too (not NGK or something else). Specific plugs were called for by engine year, but typically QL86C (1996-1998) or QL82C (1998 on).
Click to expand...

Confirmed the spark plugs are Champion QL82C
Prop 4 blade is 10.5 x 12

Prop 3 blade is 10.5 x 11

I will check the compression over the weekend and also check plug gap since I will have them out to do the compression check
 
When switching from a 3-blade prop to a 4-blade, you’ll usually need to decrease the pitch by 1 or 2 inches to keep the engine RPM in the same range.
So you will be going the wrong way with that 4 blade prop...you should be running a minimum of 5200 rpm if not nearer the top (5800) empty to give maximum motor life.

Lowest pitch prop they made for that motor was an 11" x 9" 3 blade, and you are almost there.

You may have too much boat for that motor (or not enough motor for the boat whichever, as folks above have stated). A 16' Sundance Skiff calls for 40-50hp; hull alone is 680 pounds. Add 3 extra people and I'm surprised you did as good as you did.
 
Thanks for the great information. It is good to know that there is no real issue aside from the idle issue when warm. Also thanks for the information on the props. I will give the 3 blade a try but it looks rough on the leading edge of the blades. Maybe I will file it down in an attempt to remove the rough edges it has.


What I know of this boat is it was purchased new (boat, trailer and motor package) back in 2000 by my friends grandfather.

The papers I have is a Sundance K16 but in the title it shows 15'-10"
What is strange is that the Coast Guard Sticker on the transom list a max hp remote 30 hp and 25 hp tiller but on the side console there is a sticker that shows max remote 40 hp, tiller 30 hp same Sundance k16 model on both Coast Guard stickers

Also from all the papers I have it seems that it came with the 4 blade prop and at a later time my friends grandfather put in the 3 blade prop.
It is actually awesome that I have all the papers and receipts of the boat. They kept great records on it.
 
NautiBuoys thanks for the great information. It is good to know that there is no real issue aside from the idle issue when warm. Also thanks for the information on the props. I will give the 3 blade a try but it looks rough on the leading edge of the blades. Maybe I will file it down in an attempt to remove the rough edges it has.

What I know of this boat is it was purchased new (boat, trailer and motor package) back in 2000 by my friends grandfather.
The papers I have is a Sundance K16 but in the title it shows 15'-10"
What is strange is that the Coast Guard Sticker on the transom list a max hp remote 30 hp and 25 hp tiller but on the side console there is a sticker that shows max remote 40 hp, tiller 30 hp same Sundance k16 model on both Coast Guard stickers

Also from all the papers I have it seems that it came with the 4 blade prop and at a later time my friends grandfather put in the 3 blade prop.
It is actually awesome that I have all the papers and receipts of the boat. They kept great records on it.
 
FYI, I got the info on the K16 from their website, where they show it running with a 25hp of all things.

Before messing with the idle issue, I would confirm it's running at 700-800 rpm at idle, in gear and under load. If no, you can tweak it with the idle stop easily on that engine. I would then run some engine tuner, Ring Free, Quikleen or Sea Foam through it. It might just solve your idle stall issue. It doesn't sound like the engine has been abused but perhaps not used enough, given the ethanol fuel and carb issues of recent years.
 
I was trying to reply yesterday to your comment but for some reason it kept telling me moderator needs to approve very strange.

Hmm I see my post made it after all lol
 
NautiBuoys said:
FYI, I got the info on the K16 from their website, where they show it running with a 25hp of all things.

Before messing with the idle issue, I would confirm it's running at 700-800 rpm at idle, in gear and under load. If no, you can tweak it with the idle stop easily on that engine. I would then run some engine tuner, Ring Free, Quikleen or Sea Foam through it. It might just solve your idle stall issue. It doesn't sound like the engine has been abused but perhaps not used enough, given the ethanol fuel and carb issues of recent years.
Click to expand...

It has been a busy week . I have not had a chance to do a compression test Will try to get it done during the week.
I did get the boat out on Saturday and this time It did not stall at all in idle (I did nothing to it). I did take a look and the idle RPM in gear was about 1100. In neutral I wanna say 1200. I forgot to take a picture of the reading. I did swtich to the 3 blade prop and it felt a bit faster than the last time. just a little bit.

Oh and by the way I only use Ethanol free fuel.
 
Back
Top