1988 70HP Johnson - Strange Behavior (High idle, leaking gas, etc)

[mkaminski]

Hello all...<br /><br />Some background info... I bought a 1988 70HP Johnson (#J70TLCCA) from Craigslist last January. Earlier in the month I took the engine to a reputable mechanic where I had the engine looked at. I asked that they replace the impeller, adjust the steering, perform a tuneup, and replace the lower gear oil. At their discretion they also installed new single-lever OMC controls and replaced a dead powerpack. <br /><br />I took the motor out this weekend. I noticed occasionally that after I would start it up, the idle would be very high (around 3000 RPMS) and would not subside unless I revved the engine. <br /><br />Last night, after I was leaving the canal at idle speed, I went to put the motor into gear and throttle up. The engine then died and refused to start. After a couple tries I discovered that the starter motor was stuck on the flywheel. After freeing up the gear, I tried to start again. The primer bulb lost pressure after each time I tried to start the motor. To my horror, I saw oil and gas leaking into the bay. The engine refused to turn over, and I paddled back to the dock. <br /><br />This afternoon I tried starting the motor, and it fired right up on the first try. The idle speed was normal and I did not see any leakage from the engine again. I checked the fuel lines as it was running and did not see any leakage. I even put the motor into gear quickly and revved it, and it did not crap out. <br /><br />Any ideas on what is happening? I don't want to get back out on the water and start leaking fuel again!<br /><br />

 

[fireman57]

Re: 1988 70HP Johnson - Strange Behavior (High idle, leaking gas, etc)

Sounds like your carb or throttle linkage needs a little lube so it doesn't stick. You need to find your fuel leak. When you say it refused to turn over do you mean that the starter would not turn the engine over or that the engine wouldn't try to fire? You might want to check it for overheating as a hot engine will not crank. Also, what is the picture supposed to show us? You don't have an explanation for it. If you starter is sticking put a little and I mean very little light machine oil on the shaft. WD40 will help short term but it is not a lubricant. Sounds more like an overheat problem to me.

 

[mkaminski]

Re: 1988 70HP Johnson - Strange Behavior (High idle, leaking gas, etc)

Thanks for your response, fireman. The picture shows the stain that the gas/oil leak left. Do you have any idea where I should start looking for a leak? I believe the engine was not turning over because no fuel was getting to the cylinders... it was being expelled into the bay. Also, the primer would lose pressure after each attempt to turn it over.

 

[KYHunter2]

Re: 1988 70HP Johnson - Strange Behavior (High idle, leaking gas, etc)

You said, it wouldn't turn over due to lack of fuel. One has nothing to do with the other.<br /><br /> If you meant , would turn over and not start, then.<br /><br />I've seen , the same thing as in your picture.<br /><br /> The fuel can be leaking from a couple places , that it will run down, like your picture.<br /><br /> Make real sure your line connections at carbs are not leaking.<br /><br /> Its hard to see at times , they can look , Ok . And not be.<br /><br />Check the lines for cracks, etc.<br /><br /> I'd really check , fuel pump and its connections as well.<br /><br /> It looks like more fuel, then would leak from flooded carbs.<br /><br /> It sure sounds like fuel pump , or loose connections.<br /><br /> If you find nothing there, I'd look to the carbs. Maybe a sticking float/needle.<br /><br /> Good-Luck,<br /><br /> KYHunter

 

[jtexas]

Re: 1988 70HP Johnson - Strange Behavior (High idle, leaking gas, etc)

there's a hole on the back side of the fuel pump - gas will dribble out of there when you pump the bulb and also when the engine's running, if the diaphragm has a hole in it.