1989 70hp fouling plugs

sbv16

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Apr 13, 2009
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15
Hey

Ive got a 1989 Johnson 70hp outboard which is running with the VRO disconnected. Its still using the fuel pump side of the VRO though as a fuel only pump was not put in to replace the VRO. I am mixing fuel precisely at 50:1.

I have put brand new Champion QL77JC4 plugs in it and performed a compression test with the following results:

Top cylinder 130psi

Middle cylinder 126psi

Bottom cylinder 123psi

My problem is that it fouls all 3 plugs badly. So much so that it causes it to miss and stall during light throttle. It is fine however at WOT. I have had a look at my carbies and I think I have got the early production version which do not have needle valves for adjustment etc.

I have notice that sometimes when i Tilt the motor back after use a little bit of unburnt fuel comes out of the air silencer. But it is a very small amount.

Any help would be appreciated
 

tashasdaddy

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Re: 1989 70hp fouling plugs

early model does not have the slow need valve, only the fixed jets. when you had a look at the carbs, did you clean them and use a rebuid kit? are your butterflies all the way close at idle? if not you need to do a link n sinc, and get the butterflies adjusted and the timing coordinated. see TOP SECRET FILE for carb instructions.

when you tilt the motor the carbs will drain, or overflow.
 

sbv16

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Re: 1989 70hp fouling plugs

Cheers for the reply

No I didnt do a carby clean or rebuild when I had a look, I just baught the boat and was hoping to go over everything else first.

I did check the link n sync though. Butterflies were closed at idle and open at WOT. All even as well.

So where to from here?

Is it supposed to foul the plugs with the VRO disconnected?
 

tashasdaddy

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Re: 1989 70hp fouling plugs

no, it is not suppose to foul plugs, ever. and your compression is fine.
 

sbv16

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Re: 1989 70hp fouling plugs

Time for a carbie rebuild and clean?????

I was hoping it would be something simple......
 

Boss Hawg

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Re: 1989 70hp fouling plugs

Time for a carbie rebuild and clean?????

I was hoping it would be something simple......


Looks much worse than it is :rolleyes:
Did my '87 70hsp Friday-
One of those "If I can do it" things :D
 

itsaboattime

Senior Chief Petty Officer
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Jul 4, 2007
Messages
791
Re: 1989 70hp fouling plugs

Your carbs are pouring too much fuel to the motor and it can't keep up, thats why its fouling the plugs. When it does idle does it smoke badly? The best place to start is the carb rebuild. Its not that hard, just a little time consuming and patience is needed. Take your time, do it right, and the reward will be a running outboard.
 

sbv16

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Apr 13, 2009
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Re: 1989 70hp fouling plugs

Nope no smoking from the motor when idling.

I will buy the rebuild kit tommorow and go from there.

I guess I should leave the VRO disconnected?
 

alangf

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Apr 12, 2009
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105
Re: 1989 70hp fouling plugs

If you are once sure of your carburetors including floats, float level adjustments and sealing of the needle valves the next step is to make certain the spark is as strong to the cylinder that is fouling as it is in the others. This is usually done at an outboard shop by determining how far a spark will jump from the plug wire to the block. It sounds like the needle valve in the carb is the culprit but without actually seeing it I am just taking my best guess. The easiest way to check is to squeeze the primer bulb until it gets firm and maintain pressure on it. If it slowly bleeds down something is leaking through.
 

sbv16

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Apr 13, 2009
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Re: 1989 70hp fouling plugs

Ok

I removed the air silencer cover. Tilted the motor up and squeezed the primer bulb holding it firm. There were no leaks, then i squeezed the primer bulb again and fuel came pouring out of a couple of carbies......

Is this because the float valve is not sealing or is this because I squeezed the primer so much that fuel needed to overflow?

I am assuming no matter how much I squeze the primer no fuel is supposed to leak from the bowls?
 

jsalz

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Jun 12, 2008
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Re: 1989 70hp fouling plugs

Try it without tilting motor up so that the float is level.
 

sbv16

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Re: 1989 70hp fouling plugs

nope still leaking out......

Maybe I squeezed a bit to hard cos there were no leaks whilst I was holding it firm, then that last squeeze of the bulb whilst it was hard was enough to make it gush out. Just my luck I probably squeezed it to much and caused it to leak!!!!

Is leaking at the bottom of the thin round tube sitting in middle of carb, which would be the float valve.

I did the thermostat earlier today, rules out the engine running cold due to thermostat not opening and closing.

Would one leaking carbie cause all 3 plugs to foul??????
 

Boss Hawg

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Re: 1989 70hp fouling plugs

nope still leaking out......

Maybe I squeezed a bit to hard cos there were no leaks whilst I was holding it firm, then that last squeeze of the bulb whilst it was hard was enough to make it gush out. Just my luck I probably squeezed it to much and caused it to leak!!!!

Is leaking at the bottom of the thin round tube sitting in middle of carb, which would be the float valve.

I did the thermostat earlier today, rules out the engine running cold due to thermostat not opening and closing.

Would one leaking carbie cause all 3 plugs to foul??????

No, 3 carbs- 3 plugs - 3 cylinders working independently as a unit -
Did i say that right :confused:
 
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