Re: 79 johnson v4 died on the water
Sounds like you quite possibly have several different problems going on here. Possible fuel restriction, link and sync errors, starter issues, and/or water pump needs attention. Soooo....... first things first........ If you haven't already, purchase an OEM Service Manual for your outboard! Not the clymer or other aftermarket products. You will be much better off with an OEM Manual specific to your model.
1) Before you continue running the outboard, it MUST have an adequate supply of water to cool the block. Otherwise, get your checkbook ready for a complete rebuild. You should get that under control first. How long has it been since the water pump was replaced. If more than 2 yrs, you should replace it now. If your not sure, just go ahead and replace it. Better safe than sorry. The 2 temperature sensors can be easily removed by sliding back the rubber sleeves on the brown wires, disconnecting the spade connectors, and pulling them from the heads. You can check to see if they are making contact via conecting an ohm meter to them and submerging them in a pot of hot water on the stove. A meat thermometer should be used to monitor water temp. Just going on memory here, I think they should open at around 145*F. You will need some gasket sealer to re-install them if they are good. If found defective, replacements aren't hard to find. The store here at iBoats likely has them. If you can hold your hand on the heads for more than 5 seconds, I would scratch this from my to-do list.
2) Secondly, when the outboard stalls, there is no mentioned of anything regarding the condition of the fuel bulb. Is it flat or is it still a good firm bulb (a little soft is to be expected but not overly mushy like a rotten tomato). Can you keep the outboard running by squeezing the bulb? If it's sucked flat, this would indicate the fuel pump is likely doing it's job and you have a restriction between the bulb and the fuel cell. Anti-siphon valves are notorious for sticking partially closed and restricting the fuel supply. If the outboard is new to you, and you say it is, it may be time for a carb bath and new kits installed. The carbs are a piece of cake. No need to purchase new ones. There is a walk through on the FAQ's forum for them as well. Follow it to the letter.
3) Compression seems good to me. There is a little difference in the cylinder readings, but I wouldn't be too awfully alarmed. It may be in need of a good decarb, if you haven't done that. Since this outboard is new to you, It sure wouldn't hurt to go ahead and take care of that when you get it running correctly. This needs to be done as part of your anual maintenance as well. Check the FAQ's forum for how-to's. Have you tested spark? Should be jumping a 7/16" gap, with an adjustable gap spark tester, which is available at your local automotives parts store. Check again when your troubles start. You could be dropping a cylinder when things get warm. Also, try to turn the flywheel by hand if/when you suspect it is locking up. This would be a sure way to tell. You may consider pulling the plugs first to make this task much easier. If not, then pull the safety lanyard and kill all spark first. We don't need any accidents. If, with the plugs removed, you find it to be locking up you need to stop running the outboard immediately until you determine the cause.
4) Your starter needs to be able to spin the flywheel at least 300-350 rpm to generate spark sufficient for starting the outboard. It may be time to have it rebuilt. ? Ensure all your connections are shiney clean. And I mean shiney!!!! Ensure all your cables are in good shape too. No cracks in them that may allow water intrussion leading to internal corrosion.
5) The fact that you can generate 5000 rpm with the warm-up lever suggests a link and sync may be in order. My '79 E'rude 140 will not go much higher than 3000 rpm with the warm up lever fully raised. This is assuming the boat is on the water. Do not do this at home on the muffs!!! The outboard needs to be in the water so that you have back pressure on the exhaust. If done on the muffs, and reved higher than a mere fast idle (1500 rpm's), you risk having a runaway outboard on your hands and looking at a completely ruined powerhead and a new pair of trousers will likely be in order as well!!! Have you made any adjustments to anything that could be causing this issue? Consider looking at the timer base, located under the flywheel, and make certain it isn't sticking. Also, what plugs are you running? My '79 E'rude manual suggests a UL-77V permagap plug made by Champion. I suspect yours will too. Others may recommend the QL77JC4 plugs gapped at .030. Personally, I chose to stay with the recommended UL-77V permagap plug. I have had no known issues with them as of yet. If you do a lot of trolling around, the later plug might be a better choice. I'm sure others will chime in on this. To each his own I suppose. When removed, do the plugs all appear the same? Or is one, or more, different than the others? Describe their appearance. Your cylinders are listed like this while looking at the motor from the rear of the boat:
(port side) 1..........2 (starboard side)
(port side) 3..........4 (starboard side)
4) Stop using starting fluid in your outboard. It is breaking the oil down and your not getting addequate lubrication to your cylinders. Use a premix bottle of gas and oil instead. If your getting a good spark, to go along with the compression numbers you've posted, it shouldn't be too hard to start at all when using the premix. When your problem with planing occurs, push the key in to engage the electric choke and see if the outboard picks up or stalls. This can give others a clue as to what direction you might need to go in.
5) Purchase a manual specific to your outboard. I know it's already been mentioned, but it can't be said enough. You will need this in order to familiarize yourself with the terms used in describing the various components in respect to the link and sync process.
Let us know what you find in your testing. As you can see, there is much more information required to better assist you. Check some of this out and get back with us. Good luck!!!................. ALAN
BTW........ Welcome to iBoats!!!!!
<br /><br />hope thats of some help..<br /><br />you might also look into schematics posts on fitting a temp guage to the engine, I have done this myself now, and it works great also.<br /><br />a couple of points.<br /><br />1. If you had cooked it to the point where it "sorta" locked up, I doubt you would still have compression that high. your rings would have lost alot of their tension getting that hot.<br />2. What mixture are you running it on? should be 50:1, but if I were you, I'd run it on 32:1 till you get the problem sorted.<br />3. when an engine gets hot enough to lock up, you can usually smell it.. the paint on the block and heads will be smoking and blistered and a drop of water on your fingertip dropped on your head will evaporate immediatly. (if you can touch all heads for 5 slow seconds without massive pain, its not likely an overheat problem.)<br />4. how do you know it sorta locked up? did you take the cover off and try turning the flywheel by hand? you may have an electrical problem that gets exacerbated by heat, (like the starter soleniod) I have had a similiar problem with my old LARK40. also, when you are trying to turn it over after lockup, do you have it in neutral? it won't or shouldn't turn over unless its in neutral, there is a switch near the throtle linkage to prevent that from happening.<br />5. If you can avoid it, don't keep running the engine till it "locks" to test theories.. you can kill it very easily depending on what the problem is.<br /><br /><br />rgds<br /><br />Frank