1975 Johnson 70 HP ignition problems HELP

Hello to all, I got a 1975 Johnson 70 hp. I bough the boat from someone and here is the problem. Motor start great, idle great, and runs great off water hose, in the water it die as soon i put it in gear, sometimes does not die and runs but no power. Compression test is 145/125/125. Here is what i found, #1 and #2 cylinder/coil is working, #3 is not but it has spark. I switched coils and they are good because they work on every cylinder except the #3, but again #3 has spark, but when I take the plug wire on and off the spark plug it doesn't do nothing. I search on youtube how to test the stator and seem that mine is good, it show 650 in ohms. Coils are good, so powerpack?? can a powerpack send signal to the coil and still be bad? HELP please.

UPDATE: Even know still no reply I want to go ahead and update this post, I bought a new powerpack and still same problem. #3 cylinder is not working but wire has spark. HELP

Squirt some fuel in # 3 cylinder carb once and see what happens.

Boobie said:

Squirt some fuel in # 3 cylinder carb once and see what happens.

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Will try that tomorrow and post results, thanks.

Here are the results, when I squirt some fuel in #3 rpm go higher, when I squirt fuel in #1 and #2 rpm go lower. Also, two note from a trip to the lake this morning. With the spark plug wire connected to #3 rpm go higher if I squirt fuel in the carb, when the wire is not connected it doesn't do nothing if I squirt fuel. Second note, it ran good, better than before (maybe the new powerpack help) it didn't die when put in gears, but the only problem was that to make it run I have to push the throttle all the way down, unless is all the way down there no power to get on plane. Any Help?

Hopefully, #3 carburetor is dirty. It isn't the powerpack because you have spark on all cylinders. Now, here is what you do not want to hear: Water in cylinders. That also could explain why compression is low on 2 and 3. That water intrusion is a known problem. The inner exhaust cover warps and then water squirts into the exhaust ports. This is an educated guess. Could be a false alarm.

On the other hand, PT Barnum was right.

Thanks for the quick reply. If indeed the problem is water leak, is that require to take everything apart even motor timing? Or can you fix it without dealing with timing?

fdrgator said:

Hopefully, #3 carburetor is dirty. It isn't the powerpack because you have spark on all cylinders. Now, here is what you do not want to hear: Water in cylinders. That also could explain why compression is low on 2 and 3. That water intrusion is a known problem. The inner exhaust cover warps and then water squirts into the exhaust ports. This is an educated guess. Could be a false alarm.

On the other hand, PT Barnum was right.

Click to expand...

If it does turn out that it is water damage, it means total disassembly and rebuilding of the powerhead. That doesn't necessarily mean the ignition timing is changed, but the link & sync would have to be dealt with. We are talking major work here, possibly not worth repairing. Depends on the extent of the damage and how quickly you discovered it. If it was salt water, too bad, so sad.

Let me ask you, I know the head gasket is not hard to replace, can I just take it apart and see if there water in the piston?

fdrgator said:

If it does turn out that it is water damage, it means total disassembly and rebuilding of the powerhead. That doesn't necessarily mean the ignition timing is changed, but the link & sync would have to be dealt with. We are talking major work here, possibly not worth repairing. Depends on the extent of the damage and how quickly you discovered it. If it was salt water, too bad, so sad.

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Check the high speed jet in #3 carb before you do anything else. JMO !!

This is an 8 months old thread by me, and wants to thanks all. I put all my focus on #3 carb and after a well cleaning (not new kit) runs great and i even sold it to buy a center console. Thanks again