1974 Johnson runs then quits

[vegard]

I took my boat out for the first time today. After launching, I let the boat idle for a while. After a couple minutes it died unprovoked, and we decided that that was a fluke and restarted (real fast), and set off. After about 10 minutes, the engine died at about half throttle. after a few minutes of cranking, it restarted. This happened again after another ten minutes (or so). This time it took more time and cranking, but it started. We drove some more, and then it died again, and would not restart no matter what we did. We cranked it a whole lot, and we tried all different choke, and throttle positions. We then waited a half hour and tried again, no luck. Eventually, we were towed back to shore. Heres what I did before we took the boat out:<br />carbs rebuilt<br />waterpump<br />fuel pump cleaned/checked<br />Spark plugs fire (may be weak though)<br /><br />What could the problem possibly be? I think it may be the ignition system. I dont have an analyser, so is there some way to check all this stuff? (I have a multimeter) Thanks alot. Im stumped.<br /><br />ps. Included are some pics <br /><br />

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[vegard]

Re: 1974 Johnson runs then quits

its an 85 hp

 

[Hooty]

Re: 1974 Johnson runs then quits

Since it quit, have you tried starting it on the muffs? If not, give that a try. Have a squirt bottle of premix on hand and if it doesn't start, squirt the carbs until it starts or you can see the fuel on the plugs. This way, you'll know your getting fuel. If it still doesn't start use your multi-meter and manual to check out the electrical components.<br /><br />c/6<br />Hooty

 

[vegard]

Re: 1974 Johnson runs then quits

The manual calls for a neon test light and an ignition analyzer. I do not have these instruments. Do I need to get them? or can I do these tests with my multimeter (if so, how?). Also, I found that the rectifier diode was bad. could this be the whole problem?

 

[Hooty]

Re: 1974 Johnson runs then quits

Usually, when the rectifier goes south, the tach quits working and the battery doesn't charge. Occasionally, a bad rectifier will keep the engine from running but not very often. Your manual shoud give resistance values for the different components and instructions on how to check diodes.<br />You didn't answer. Have you tried starting the engine on the muffs?<br /><br />c/6<br />Hooty

 

[ezeke]

Re: 1974 Johnson runs then quits

If you have a minute, what kind of fuel tank are you using?<br /><br />Once your battery is weak, you will not be able to start that motor - it has to turn at 300RPM minimum to start. Get a fullly charged battery and try it again.

 

[ezeke]

Re: 1974 Johnson runs then quits

All you need to check the rectifier is an ohm meter.<br />Read Joe Reeves rectifier test info:<br />"<br />Joe Reeves <br />OMC Guru <br />Member # 6826 <br /><br />posted September 13, 2003 11:10 PM <br />--------------------------------------------------------------------------------<br />Ron..... Only replace a rectifier if it's faulty. If it's a water cooled regulator/rectifier type, you'll need a manual to check it. If it's the small three (3) wire type, the following procedure would be the one to use.<br /><br />(Small Rectifier Test)<br /><br />Remove the rectifier wires from the terminal block. Using a ohm meter, connect the black lead of the ohm meter to the rectifier base (ground), then one by one, connect the red lead of the ohm meter to the yellow, yellow/gray, then the red wire (some rectifiers may also have a yellow/blue wire. If so connect to that also). Now, reverse the ohm meter leads and check those same wires again. You should get a reading in one direction, and none at all in the other direction. <br /><br />Now, connect the black lead of the ohm meter to the red wire. One by one, connect the red lead of the ohm meter to the yellow, yellow/gray, and if present, the yellow/blue wire. Then reverse the leads, checking the wires again. Once more, you should get a reading in one direction and none in the other. <br /><br />Note that the reading obtained from the red rectifier wire will be lower then what is obtained from the other wires. <br /><br />Any deviation from the "Reading", "No Reading" as above indicates a faulty rectifier.<br /><br />--------------------<br />Joe (30+ Years With OMC)<br /><br />--------------------------------------------------------------------------------<br />Posts: 1597 | From: Central West Florida | Registered: Feb 2002 | IP: Logged "

 

[Sotey]

Re: 1974 Johnson runs then quits

Something possibly to check before you do major maintenance. I have a 1975 and had the same problem. When you put your fuel pump assy back together make sure you installed everything correctly, I had put a part back on at 10 o clock instead of like 3 oclock position. It worked great after that was fixed. Also if that doesn't work make sure your tank vent is open. Good luck.

 

[OBJ]

Re: 1974 Johnson runs then quits

Hey vegard.....<br /><br />Couple questions....<br /><br />When it restarted, did you have to pump up the primer bulb again? Did fuel system seem empty?<br /><br />Did you check for over heat? This would have probably been obvious.<br /><br />Just a "gut" feeling here, I think your losing fuel. Make sure your connections are tight and the hoses are all servicable. They should have some flex to them and not be hard.<br /><br />And it wouldn't hurt to check all connections on the igniton system either. Make sure they are clean and tight.<br /><br />The neon test light has been replaced by the Stevens test meter which is a glorified peak reading volt meter that you can switch polarities on.<br /><br />Keep in touch on what you find...thanks.

 

[vegard]

Re: 1974 Johnson runs then quits

I doubt that its a fuel problem. I did not have to pump the primer to get the engine started again. fuel pressure seemed strong the whole time. I Know for a fact that the rectifier diode is blown, because I did test it as you guys described. I have not run the motor on muffs yet because it is in partial dissasembly, but I will try today. I dont think the battery is weak, its spins the motor real well, but Ill charge it anyway.

 

[vegard]

Re: 1974 Johnson runs then quits

fuel tank Im using: built in that I just installed after a good flush. The gas is super fresh, and the fuel system is clean.

 

[vegard]

Re: 1974 Johnson runs then quits

There are three test that I would like to perform, but require the neon tester: Sensor coil input check, Charge coil output check, and power pack output check. Is there anyway to test these without a Stevens test meter, or should I buy one?

 

[vegard]

Re: 1974 Johnson runs then quits

It didnt overheat... I dont have a buzzer connected yet, but I could put my hand pretty much anywhere on the thing and it was bearable.

 

[vegard]

Re: 1974 Johnson runs then quits

ok, I tested resistance in the coils... <br />Sensor coils both measured 11.6 ohms, manual wants 8.5+-2<br />Charge coil measured 600, manual wants 910 +-75<br /><br />Nothing is shorted to ground. So do you think I need to replace the stator?

 

[vegard]

Re: 1974 Johnson runs then quits

ok, I have strong spark on all four when cold and cranking the starter.<br /><br />I left my spark plug wrench in the car when I was out yesterday, so I couldnt check spark when it failed, but I assume that was the problem.

 

[ezeke]

Re: 1974 Johnson runs then quits

OK, disconnect and tape all of the rectifier wires after making a chart so you can put the wires back when you get the new one. The motor should run without it. You won't have charging and your tach will not work.

 

[ezeke]

Re: 1974 Johnson runs then quits

OK, disconnect and tape all of the rectifier wires after making a chart so you can put the wires back when you get the new one. The motor should run without it. You won't have charging and your tach will not work.

 

[vegard]

Re: 1974 Johnson runs then quits

I will do that as soon as I can, but I pulled the heads out because I had a suspicion that my engine was rebuilt recently, and it was (new sleeves), so I need to buy new gaskets before I can put it back together. None of my johnson dealers seem to be open on sundays...

 

[GRAPPAJOE]

Re: 1974 Johnson runs then quits

I have a feeling that your problem is one of two things your power pack or your coils . I have a 140 johnson that was having the same problem once the start heating up they start to misfire or stop working all toghether until they cool down

 

[vegard]

Re: 1974 Johnson runs then quits

Ok, Im trying to start it on the muffs with a replaced diodes (those things must be made of gold), and it ran for about 5 seconds and died. I do have spark, so now Im thinking fuel. maybe my carbs clogged again? I will try with a spray bottle to the carbs now.