1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of gas

[AiricR]

Motor is a - 65ESL73R

I just bought this boat and motor. Gutted the inside the first day and put it in the water to test the motor the next.
It started just fine.... Idled just fine and ran like a top for about a half hour. Could not believe how quite this motor is.
About the third up and back lap the motor started acting like it was running out of gas. Apply throttle and it would bogg down.
Backed the throttle down a bit and cruised back to launch.
1.) Checked gas, A bit low so I filled up the tank with gas and oil
2.) Checked for kinks in line
3.) Checked the vent hole and primer bulb. Primer bulb never seemed to be "Hard" still had squish left.

Left dock and tried it again..ran like a top for about 5 min then the same thing happened. I idled to check tank and connections again and it died and would not start back up again.

Last night I tried to start and run on Ears but I could not get it to idle

 

[oldcatamount]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

Check the ignition spark. It should be strong and blue on all cylinders. Are the plugs cleaned and gapped right? If the ignition checks ok, it sounds like you need to clean and re-build the carbs. Will it run if you spray fuel/oil into the carbs?

 

[AiricR]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

Haven't gotten that far as of yet...Been reading a bunch. I'm getting a new Battery,gas tank and fuel line today. I am far from mechanically inclined. I didnt get much history on the motor but the person I bought it from said it sat for years. I asked him what he did to get it going and he said just put new fuel in and it started right up. So he changed plugs and ran it. I can still smell a slight aroma of that nasty old gas smell every now and again so Your probably right on the carb clean.

 

[AiricR]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

Installed New battery,Fuel Line and Tank with fresh fuel and oil.
Motor Started and idled for 25-30 min. 4 different Times yesterday as I was working on other things.
I may take it out today and see if it will run any better under load
My youngest just informed me I'll be doing this alone...LOL.

 

[oldcatamount]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

Good job!

 

[Whitakerla]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

AiricR, I am having the same identical problems on the same identical motor. Just curious if you had any luck today with the motor under load?

 

[AiricR]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

I did not. I ran up and back a few times... 300 yrds each way... about 3 times staying close to the launch. After a warm up I wanted to see if it could idle and still run so I let it idle after about 35 min and it idled fine for about 5 min then just shut off. Could not get it started after that....I have yet to see any water comming out of the two top ports....But from what I have seen or heard its not supposed to. But ive seen videos on Youtube and water does come out of these two wholes... So I dunno. This Motor runs perfect and so quiet untill it gets warm then boggs down and will not Idle. I found someone in town that works on older Johnsons so I think Im gonna take it in tomorrow and hope he's quick...LOL

 

[Sander]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

I'm not expert but it sounds like your motor is overheating. Hot horn in working order?

 

[BonairII]

Re: 1973 Johnson 65 Hp - Ran great until warm then acted like it was running out of g

I'm not expert but it sounds like your motor is overheating. Hot horn in working order?

You read my mind. When I read that he hadn't seen any water coming out of the motor, I thought "that ain't good"