Thread: 1970's Johnson 25 horse losing power

Scrapper - The motor has a tiller so squeezing the bulb while I am running will be easy. BTW the stiffness is due to the material the hose is made of which is gray. I was mistaken thinking it was black rubber. I will keep you posted

Originally Posted by cricket george

No sir. I checked that. I have been told to check for an air leak on my connections to the bulb, tank and engine for a loose clamp. I will check that today.

You do understand that since you are able to force fuel out of a connection with the bulb that this condition exists, right?

Your "air leak" is where the fuel is exiting. If it's hose clamp tightening should cure it. If it's the connector some carb cleaner and "working it" on and off should work. The ball that "seals" the connection when removed is likely dirty and/or the small seals are deteriorating. If it's the seals you will likely need a new connection. If the motor and tank always stays in the boat you could always just eliminate the quick connect, that's what I did with my little 25hp.

MDCrappie - The fuel came out of the connector not behind the end. I did not think about the connector ball being dirty or the deteriorating seal. I can easily replace it today and kill 2 birds with 1 stone. Thank you.

Originally Posted by cricket george

MDCrappie - The fuel came out of the connector not behind the end. I did not think about the connector ball being dirty or the deteriorating seal. I can easily replace it today and kill 2 birds with 1 stone. Thank you.

While you're replacing make sure your hose is not the older style Mercury hose. If it's "hard" I think it's likely attwood, but if it's the older Mercury hose the interior could be dissolving causing you some problems.

Duplicate post

MD - The hose is an Attwood's and when I squeezed the bulb again today to duplicate the gas leak nothing exited. I did notice when I squeezed the bulb tiny air bubbles coming out around the seal on the tank gasket. I tightened the screws around the gasket and the bubbles quit and still no exiting gas from the connector at the motor. It seems that the system is now tight. Now I need to take the boat out for a test run and see what happens. Any thoughts??

I have a thought. I went back to your first post and reread. After what you say about tiny bubbles on "tank gasket", that leads me to think the second poster may have gotten it. Are you SURE the vent is venting?? If you had tiny bubbles or air pushing through the tank gasket that would lead me to believe the vent is not venting like it should. Have you tried to run it with the gas cap loose or off? 10-20 mins of run time and it shuts off sure sounds like a vent problem. I'm sure you checked it but just wanting to make sure. I rewired a 78 Johnson 140 I got really cheap and could NOT get to run correctly. It did not run correctly before...this is why I got it so cheap...lol. Anyways...it would miss...like two cylinders were firing backwards...if you've heard this you l know exactly what I mean...lol. I checked, checked, checked....looking everytime at the schematics. One night Agrihawg and I were working on some stuff and I saw it. The powerpack wires were reversed on the engine harness side. OH MY...I had piddled with this thing and could have sworn up and down the wiring was correct. Just didn't see it right until then I guess. Felt kind of silly but was SURE glad to find it finally. lol

Originally Posted by cricket george

I did notice when I squeezed the bulb tiny air bubbles coming out around the seal on the tank gasket.

Not sure why this would happen (if the bulb is pointing the correct direction and working properly) it should be "drawing" from the tank, not forcing anything into the tank.