82 Johnson 70hp - Cheat with the choke to take off?

I've been having some "taking-off" issues lately where the motor doesn't take the gas and dies out when too much throttle is given. So I brought it in to my repair shop where they soaked the carbs and put in 3 new carb kits but unfortunately after taking it out again, it still has the same problem.

On the muffs it's fine, only under load will it die out. When it starts bogging down I can quickly hit the choke and the thing takes off. Once going, the motor runs great, I can let off the gas and then WOT just fine. However if I shut it off for 10secs or more and then try to take off again, I have to hit the choke to go.

What can this be?

Re: 82 Johnson 70hp - Cheat with the choke to take off?

Have you checked the fuel pump or the fuel pump diaphram? You might have a ruptured diaphram and need to rebuild....

Re: 82 Johnson 70hp - Cheat with the choke to take off?

ftltony said:

Have you checked the fuel pump or the fuel pump diaphram? You might have a ruptured diaphram and need to rebuild....

Click to expand...

No I haven't and to be honest I'm not really sure how. So basically the pump could have a hard time getting started but once the motor goes with the choke, the pump starts going again?

How much work is involved with a rebuild?

Edit: I'm also suspecting a small fuel leak, could the pump be leaking if the diaphram is ruptured?

Thanks

Re: 82 Johnson 70hp - Cheat with the choke to take off?

Follow the linkage and synchronization instructions in your service manual. Your linkage is probably not synchronized for the throttle and timing levers after the carburetor work.

You don't meed to do anything with timing. Just follow the instructions for the throttle plates and the marks on the throttle lever.

Re: 82 Johnson 70hp - Cheat with the choke to take off?

ezeke said:

Follow the linkage and synchronization instructions in your service manual. Your linkage is probably not synchronized for the throttle and timing levers after the carburetor work.

You don't meed to do anything with timing. Just follow the instructions for the throttle plates and the marks on the throttle lever.

Click to expand...

Not saying this isn't the problem but would this not affect the motor all the time, not just on take off? Because once I hit the choke and go, it runs smoothly. Only when I let it sit for 10secs will it start doing it again...

Re: 82 Johnson 70hp - Cheat with the choke to take off?

In reference to "Ezeke's" reply, did you screw with the linkage at all right about the time it started? Maybe you can get the guys at the shop to look at it for free since they didn't fix the problem you brought it in for ....

As for the diaphram, its pretty easy to fix once you have the fuel pump out. The real HASTLE is getting the fuel pump off the motor to do the job!

Put your "cussin' pants" on because it can get a little tricky!

Re: 82 Johnson 70hp - Cheat with the choke to take off?

ftltony said:

In reference to "Ezeke's" reply, did you screw with the linkage at all right about the time it started? Maybe you can get the guys at the shop to look at it for free since they didn't fix the problem you brought it in for ....

As for the diaphram, its pretty easy to fix once you have the fuel pump out. The real HASTLE is getting the fuel pump off the motor to do the job!

Put your "cussin' pants" on because it can get a little tricky!

Click to expand...

When I bought it 3months ago, I could only test it with the muffs and it ran great. Only when I took it out on the water did I notice it was doing that. The first few runs were ok but it just seemed too get worse the more I ran it. Now if I stop it for more than 10secs or so, I can't even give it the slightest amount without having to choke it to go, or else it just bogs down. It's amazing how just hitting the choke makes it go, I swear it's like hitting the Nitrous button.

As for the guys at the shop, I was trying to make a long story short but I got the carbs rebuilt first and then brought it back since it didn't change nothing. They ended up taking them off again and soaking them for free. I'll bring it back again and have them do it. I'd just like to go in a little more educated and perhaps point them in the right direction, even though I don't think I should have to, just a little fed up at this point. Any help is really appreciated, thanks.

Re: 82 Johnson 70hp - Cheat with the choke to take off?

Hello kehops,

I have a 2001 Johnson 150 and I have the exact same problem. It happens primarily in the summer months when it is hot.

I have owned this boat since new in October 2001 and it started happening the very first summer.

Just got back from a week of Scout Camp and it did the same thing and now I am on a mission to try to get it fixed.

The answer I get from most mechanics is similar to your experience. Carbs need to be adjusted.

I am not sure if I believe that expecially after what you have reported here.

My problem is in the transition from 600 RPM to 800 RPM.

Choking in this range gets you "out of the hole" and on your way.

I am amazed that the mechanics I've talked to have never seen this before.