1988 70hp johnson

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imported_Bassin

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I've had this engine for six years now without a single problem. Immediately experienced problems when I mixed older MTBE fuel with the new Ethanol fuel. Sluggish, cutouts and refused to idle, progressively got worse with each outing. Going to change fuel lines, filter, plugs and primer bulb. Any other suggestions?
 
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dakotarmx

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May 22, 2006
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Re: 1988 70hp johnson

bassin sounds like a good plan to me .give her a once over fresh fuel take her out and run for a while .hope it clears up
 
jtexas

jtexas

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Re: 1988 70hp johnson

welcome to the forum.

If it was mine I'd go ahead and do a compression test and a spark test just to rule out anything else but fuel.

If that's a built-in tank, I'd drain it and flush it out. Inspect the vent and anti-siphon.

Seafoam in the fuel might do the trick, with luck you won't be looking at a carb rebuild.
 
rickdb1boat

rickdb1boat

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Re: 1988 70hp johnson

I'd change out the carb kits to the more modern version if you haven't done so already. A local Rude Mechanic told me that anything older than 1990 should have new parts installed in the carbs to prevent failure from the ethenol.
 
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Kevin W

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Re: 1988 70hp johnson

Rebuilding Carbs, inline water separating filter, and Seafoam.
Those are what solved all my problems with the E10 gas.
Basically what can happen is the gas b4 Ethanol gas left some deposits and after years of deposits ehanol was added which has cleansing properties.
the Ethanol dislodges all the years of deposits with the first tank or so of fuel.
Guess where it ends up? hopefully your fuel filter but most likely your Carburetor.
It also pulls moisture out of the air.

The rebuilding of the carbs cleaned out the deposits.
The inline water separation filter made sure of no water or crud.
the Seafoam prevents water and stabilzes gas along with preventing carbon buildup.
 
jtexas

jtexas

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Re: 1988 70hp johnson

Also the stations have drain and clean their tanks before the first load of E-10, or else you can end up with some of their crud, too. And water. There were some stations in our area that might not've taken it that seriously. After the first load it should get better.

If rickdboat is right, you might oughtta think about a fuel pump kit, too. I'd heard that E-10 is not really worse on engine parts than MTBE fuel - the critical change there is the switch to oxygenated from non-o2 fuel - but I can't site an authoritative source.
 
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Kevin W

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Re: 1988 70hp johnson

It is my understanding that engine parts after 1985 have been built to used 10% ethanol gas.

E10 gas is not a problem in itself.
Switching to E10 can cause issues sometimes.

I was also thinking it may not be a bad idea to decarb your engine first before going nuts rebuilding everything.
See the FAQ section on decarbing.
 
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imported_Bassin

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Re: 1988 70hp johnson

Took her apart this weekend found water in carbs, lines, pump and gee the tank too... The fuel was topped up end of August. Must have had a bad load of fuel. Hopefully, no damage to the carbs and pump. The water was cloudy red brown color.

Thanks Ethanol!!!

Drain the tank, put in seafoam and keep you all posted... Thanks for the help/advice
 
rickdb1boat

rickdb1boat

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Re: 1988 70hp johnson

The water was cloudy red brown color
Click to expand...

Sounds like rust to me.....Do you have a metal fuel tank? Might look at it real good...
 
jtexas

jtexas

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Re: 1988 70hp johnson

My dad filled up an old fuel tank once, discovered it leaking out a rust hole in the bottom, transfered the fuel to another tank, and proceeded to foul his carbs with tiny little rust particles. Nothing a rebuild couldn't cure. 8)
 
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