Frustrated

[JD2]

I am getting near the end of my patience! The old Johnson 70hp 1977 Seahorse I have, starts well and warms up no problems when it's in my driveway and earmuffs are applied. When in the water it starts up and seems to have problems warming up and when i get going under acceleration, bogs down! If I take it easy on acceleration it seems to gather momentum and runs well. If I stop for a while and then restart the motor stalls under accelaration, if I stop and restart within 5 minutes the motor performs instantly and with no problems!. It will run all day cruizing after it seems to get itself together. I have had it tuned and serviced by 3 seperate marine specialists and they all report what a great old motor. has great spark and advances wonderfully to use a term. Compression is 100 to 125 over the 3 cylynders. Also
have replaced the fuel pump, spark plugs, coils and power pack with no difference.
Still bogging down under constant accelaration, the carby's have also been kitted out. New fuel and fuel lines plus tank!
I am now being told that it could be the butterfly shafts on the carbys being worn, but I seem to see very little movement on them. Remember the jets are pre set so fuel mix adjustement is out of the question.
I am about done! Every where I go is something different for the same original problem and costs are mounting up.
Would Seafoam or a similar product do the trick?
Please end my frustration!! Thanks

 

[boobie]

Re: Frustrated

Try doing a good decarb on it and see what happens. Your compression looks a little out of wack.

 

[rpsloan]

Re: Frustrated

Explain on how to do a decarb. I am at my wit's end myself chasing a similar issue.

 

[boobie]

Re: Frustrated

It's not polite to hijack a thread. Read the rules at the top of the forum. Also check the top secret file when there. It gives decarb instructions.

 

[woody66912]

Re: Frustrated

Try doing a good decarb on it and see what happens. Your compression looks a little out of wack.

As boobie and I have posted before, a engine needs four things to run.
Air, fuel
Ignition
compression,
Exhaust,
I would remove the side cover, on the exhaust side, not that big of a deal you will only need the gaskets to reinstall. A engine this old could easily have the exhaust half plugged. If it can't breath it can't run.

 

[rpsloan]

Re: Frustrated

I apologize. You offered a solution that I hadn't heard of before and was interested in trying it for myself. Found the process where you said to look.

 

[boobie]

Re: Frustrated

No problem, glad you found it.

 

[JD2]

Re: Frustrated

No problem, glad you found it.

I am excited!
Will try asap and let you know. We can't get Seafoam in australia will a basic carby foam cleaner product do the job?
Thanks for your insights!

 

[JD2]

Re: Frustrated

I have looked foer the secret file, but this aussie boy is new to this.
can you please explain weher the info on carby decarb is, I can't even find the rules! Sorry!

 

[JD2]

Re: Frustrated

Sorry guys found the secret file that it is why it is sectret.
Let you know how I go!
Cheers

 

[durban]

Re: Frustrated

it wouldnt surprise me if you are getting water on no3 or no2 plug .

 

[woody66912]

Re: Frustrated

it wouldnt surprise me if you are getting water on no3 or no2 plug .

If that's the case he could find it when he pulls the exh cover, good add on to the thread.

 

[Home Cookin']

Re: Frustrated

also could be funky fuel in the tank. try running off a remote tank with fresh fuel hooked straight into the motor (bypass fittings; they can leak air, too)

 

[EddiePetty]

Re: Frustrated

Humm......

Kinda sounds to me like the thermostat is malfunctioning......especially the part where the motor runs nicely after a brief shutdown.

Just sayin'. :joyous:

 

[Bill3434]

Re: Frustrated

My marine mechanic said the same thing, it's also a common place for a leak. Mine wasn't has bad a OP engine but my first clue was an occasional small (small) drop of water on the upper spark plug tips. Mine is a 77, 70hp.

As boobie and I have posted before, a engine needs four things to run.
Air, fuel
Ignition
compression,
Exhaust,
I would remove the side cover, on the exhaust side, not that big of a deal you will only need the gaskets to reinstall. A engine this old could easily have the exhaust half plugged. If it can't breath it can't run.

 

[JD2]

Re: Frustrated

Guys, really appreciatte all your feedback.
Did a de carb, boy what crap came out the motor with that, but I still had the same problem! I then took it to an old bloke that was "handy " with general motors (we all know one). He took of the air filter and in his opinion I had to much movement in my butterfly arms, he suggested before I spend tooo much more $$ on this motor, that I take it out on the water and when it bogs down quickly hit the start key to engage the choke, causing the motor to suck fuel. I did this and off she went, I have been out several times now and every time it bogs down on accelaration I just hit the start key innitiallizing the choke and off she goes instantly. I hop ethis helps.

 

[tx1961whaler]

Re: Frustrated

It helps.
Either the carbs are clogged up, or the carb linkage is not synchronized properly.