Engine cutting off high rpm .

[Markiemrk]

My 2000 Johnson 40 HP. Started cutting out after I got up to higher speeds . I heard the alarm go off and realized I was low on the oil that gets mixed with the gas . The boat started and ran but would cut out after I tried going at higher speeds for any length of time . I wound up going back to the marina at speeds less than 30000 rpm . Once home I filled the oil tank . Went out a few days later thinking that would solve the problem , same thing soon as I go to higer rpm’s it would cut out . It seemed like it was lacking power and not enough even enough to get up to plane. I checked the fuel filter blew it out. Trimmed the ends of the fuel line where they seemed a little cracked and reconnected the lines to the motor and external gas tank . Nothing changed . I swapped out the fuel line and primer bulb with another I had in the boat . It ran much better but seemed a little weak to me. With this fuel line it ran better once running , had more difficulty starting it with this line and the ball never seemed to stay firm . Ran the boat several miles . Took a break for a few hours and took the boat out again . Again some difficulty getting it started , seemed to be running well . After a 3 Mike run it started doing the same as before dying out at higher rpm’s . Got back at lower speed .
Just wondering what might be causing these symptom. Do I need an entire new fuel line and primer ball ? New external tank ? Is it a pressure issue ? The original ball was soft and easy to pump and stayed firm . This one is hard to squeeze and doesn’t seem to stay firm even when I pump it without the engine running . Doesn’t seem to be leaking and why would this line make the boat run closer to normal .. just not sure how to trouble shoot or diagnose these issues . Any tips or suggestion would be appreciated.

 

[racerone]

Model # is ?----Primer bulb does not need to be hard once engine is running.-----How did this motor run for you last season ?----Post the results of a compression test here.----Once those are posted you will get better responses here.----Water pump impeller replaced ?----Overheat warning horn tested by you ?

 

[Markiemrk]

Model # is ?----Primer bulb does not need to be hard once engine is running.-----How did this motor run for you last season ?----Post the results of a compression test here.----Once those are posted you will get better responses here.----Water pump impeller replaced ?----Overheat warning horn tested by you ?

Shouldnt the bulb pump til it’s firm and can’t be pumped any harder before the engine starts? The old bulb would get hard to where it wouldn’t squish anymore . The second line I put in the bulb doesn’t get hard to where I can’t squeeze it anymore . The boat has benn running great for me the last several weeks I had taken it out 6 or & times in the last month . I’ll look into the compression test is that something I can run on my own or do I need special equipment or experience ti do so ? I don’t believe the impeller had been replaced the last time I had the engine serviced probably 10 years ago . I have not tested the overheat warning horn . Is that the long beep sound that sounds when you have low 2 cycle oil ?

 

[Markiemrk]

Model # is ?----Primer bulb does not need to be hard once engine is running.-----How did this motor run for you last season ?----Post the results of a compression test here.----Once those are posted you will get better responses here.----Water pump impeller replaced ?----Overheat warning horn tested by you ?

Can a compression test be done cold ?
Will it give me an accurate reading ?

 

[Markiemrk]

I had a minute to check out the motor today . I removed the spark plugs , which were recently replaced back in November . They were very brownish black with a lot of build up on them . I can send a picture of the plugs if that would help diagnose anything. I tried testing the horn according to the manual . The key self test beeped , but the horn did not sound after touching the jumper wire to a ground . I wasn’t clear on what to check next. The impeller hasnt been replaced in probably 10 years if it was replaced when I had the engine checked then . The water was coming out the engine last week when I ran the engine . I did a compression test cold on the engine . The top cylinder read just under 60 psi. The bottom cylinder read 30 psi . I wasn’t sure how to cut the power to the fuel pump . How much would the gas in the cylinders and being cold affect the reading? What does this difference in the pressure mean and is it something that can be corrected ?

Any input or suggestions would be appreciated .

 

[racerone]

Remove cylinder head.----You have a bad gauge , bad head gasket , or a motor that needs lots of work ( overhaul ) I say.----A VRO fuel pump runs off crankcase PRESSURE pulses.-----The wires are for the warning system.

 

[Markiemrk]

I happened to look on the internet to see what a used motor would cost if I decided to go that route rather than fixing the 40 hp . Here is a listing I found. My boat says it can take up to a 75 hp motor . I figured a Johnson would be compatible with my boat . It’s a 2000 logic , center counsel v 175 triumph boat . Just wondering if the steering and throttle would be compatible .

Very Clean, low hour 2000 Johnson 70 horsepower 2 stroke, 3 cylinder outboard motor for boat or pontoon.


Long shaft (20 inch transom Length).


Non VRO (You must mix oil with the fuel).


Power tilt and trim with switch on cowl.


Like new prop.


Fresh gear lube.


New impeller.


Top Mount controls (for pontoon).


Deutsch connector on main harness.


Good compression 135 , 130, 138


Water ready.


Just wondering what would be a fair price for this motor in good to like new condition ? Also what other questions would be go to ask the seller or any other tests or inspections I could make or ask if they have been done .

 

[saltchuckmatt]

Not sure why you're giving up on your motor unless you've confirmed it's toast. First of all, a long solid tone is an overheat and for some reason it seems like maybe you're in limp mode even though it should be slightly less RPMs.

By the way 30,000 RPMs is a hell of a motor.

Lol, that being said low oil is a beep beep beep beep noise and is not constant. So yes there's a good chance you smoked the motor by overheating it. Water coming out of the telltale or the pee hole is not a sign that the engine is getting water, it's only a sign that the pump is still pumping water.

Assuming that maybe I'm wrong when you added oil to the bottle did you bleed out any air it might have gotten into the line? Or did you have a significant amount of oil in the bottle?

Have a friend, family member or neighbor come help you double check the compression. Those motors are super reliable but they cannot take an owner who has no idea what he's doing, not that I'm saying you have no idea but you're definitely having trouble.

Again, diagnose the motor and whether it's good or bad you will know a lot more about OMC motors.

I wish you the best of luck and let us know if we can help you out anymore.

 

[Markiemrk]

Not sure why you're giving up on your motor unless you've confirmed it's toast. First of all, a long solid tone is an overheat and for some reason it seems like maybe you're in limp mode even though it should be slightly less RPMs.

By the way 30,000 RPMs is a hell of a motor.

Lol, that being said low oil is a beep beep beep beep noise and is not constant. So yes there's a good chance you smoked the motor by overheating it. Water coming out of the telltale or the pee hole is not a sign that the engine is getting water, it's only a sign that the pump is still pumping water.

Assuming that maybe I'm wrong when you added oil to the bottle did you bleed out any air it might have gotten into the line? Or did you have a significant amount of oil in the bottle?

Have a friend, family member or neighbor come help you double check the compression. Those motors are super reliable but they cannot take an owner who has no idea what he's doing, not that I'm saying you have no idea but you're definitely having trouble.

Again, diagnose the motor and whether it's good or bad you will know a lot more about OMC motors.

I wish you the best of luck and let us know if we can help you out anymore.

Not sure why you're giving up on your motor unless you've confirmed it's toast. First of all, a long solid tone is an overheat and for some reason it seems like maybe you're in limp mode even though it should be slightly less RPMs.

By the way 30,000 RPMs is a hell of a motor.

Lol, that being said low oil is a beep beep beep beep noise and is not constant. So yes there's a good chance you smoked the motor by overheating it. Water coming out of the telltale or the pee hole is not a sign that the engine is getting water, it's only a sign that the pump is still pumping water.

Assuming that maybe I'm wrong when you added oil to the bottle did you bleed out any air it might have gotten into the line? Or did you have a significant amount of oil in the bottle?

Have a friend, family member or neighbor come help you double check the compression. Those motors are super reliable but they cannot take an owner who has no idea what he's doing, not that I'm saying you have no idea but you're definitely having trouble.

Again, diagnose the motor and whether it's good or bad you will know a lot more about OMC motors.

I wish you the best of luck and let us know if we can help you out anymore.

So since my last post I had a marina mechanic that works on Johnson’s run a compression test on my 40 hp . Numbers were 120 top and 95 bottom . I had my eye on another Johnson 70 hp and was told the compression was 135, 130, 138 . I Went to look at it today and the guy ran the compression about 10 15 minutes after the motor was run for a few minutes . It read 135, 120, 130. I didn’t like that 120 . Is that too much outside the 10% differance range to be concerned about ? It just bothered me that the numbers didn’t line up with what he had listed And that the one was lower more than 10%. It’s making me wonder if I should look into the issues with my original motor or go with the 70 hp if that compression is still acceptable . What can I expect out of them . How do engines with those numbers run ? What do the numbers mean exactly ?

 

[racerone]

That 120 is not a good omen.-----

 

[saltchuckmatt]

Two posts, the same thing in the head man and I boats says it's a bad omen.

I'd have to say I disagree but he's the head man.

Please refer back to my prior post. The hell with the motor do you trust the person in front of you.

 

[Markiemrk]

That 120 is not a good omen.-----

The guy spayed some stuff , forgot what he said it was , into the spark plug hole said it would clean some of the carbon on the rings and that it might make the compression go up right away . He tested it again and it was the same . He then said proper way to do it was to run it through the cylinder then let it sit over night and then run it again tomorrow to see if it ups the compression . If it’s better tomorrow would that be a good sign that it was just carbon on the rings ? What would be an acceptable number if it goes up ?
Is that just a temporary thing?

 

[racerone]

There are known issues with #2 cylinder.