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J70 Running Great! Now its Not.

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Asport-16

Contributing Member
Hey all. Ive been on here before about my 98 Johnson 70. It had an idle issue, where it was a little high. Thanks to some comments and good feedback. It ended up being my #3 butterfly was just slightly opened, so did the correct sync and link, and up until now i was just enjoying my boat. So its been running very good, all of a sudden it just dies at in very low gear. I usually idle up and down this river all day long without plugs fowling, every once in a while ill run a stretch mid throttle to clear her out. Once in a great while ill do her wide open briefly, but i dont like to push her where its 20 yrs old. So i started her back up shell stay running then bogs out! She starts right back up again and bogs out every time. I dont need to prime the bulb just start her and after 15 seconds or so right before she dies, i try to keep her going but then she chokes and dies. Ive cleaned and rebuild the carbs recently before this issue plus a decarb. New fuel lines from tank to under the cover. New tstat. Ive only been doing my own work with about 7 months experience so i dont want to screw her up because i dont have that much experience. Ive pulled the plugs they are oilly but brown no white spots. I did notice it seems shes not blowing the usual amount of smoke which since i changed over to Johnson Premimiame it hasnt been as smokey with that better oul. Ill day now my VRO is intact and im one of the few who wants to keep it that way, to me the setup is more organized, nice clean tank and oil in its own tank. Its been that way for 20 yrs and no problems,so far . All the warning horns work. But i got paranoid anyway thinking maybe it went and with all the times ive been starting and running her, that maybe it did go and all the horror story are true. So did a comp test #123 all 143 across the board with a warm engine. So im thinking now about tearing into the carbs, and figured id chime in here first. Im stumped i dont think shes flodding out it seems its a lack of fuel issue. I changed out my tacor and put on a new bulb. Sorry for such a long story. Any help would be appreciated. Its the circuitry of that motor where im scared. Its got a SLOW mode and quick start features built into it. So im hoping its a simple problem,
 
Sounds to me like a spark problem. When it acts up can you start it right up without choke/priming? Plugs wet/oily? Maybe a spark test is in order?
 
It does sound like an ignition issue, at least that’s a good place to start.

So so you’re trolling on the river? While your 70 should be able to idle just fine that’s not really how an engine like this runs best. Is there any chance you can install a kicker plate on the boat and use a 9.9 or 15 kicker motor for these low speed runs? I think that would work a lot better than idling a 70 HP all day.
 
Yeah, i can start it without choking or priming. In fact the bulb stays firm. As far as the trolling goes your right about the idle. I did state i throttle it up id say about every 15 min or so. I quite often anchor and shut it off. Theres shallowing everywhere here so you have to keep the speed down. The boat is a 16’ aquasport. Ill do a spark test today. If the test comes out bad what we thinking, powerpack or maybe stator?
 
I've done the same work as you Asport on my 1977 70hp Evinrude plus new coils, wires and plugs. It starts,idles and runs fine until I put it in gear and add a little throttle, then it just dies. :p :confused: I'm waiting for the answers to this thread as to where to look next.
 
Well im starting to think its the stator. It has the symptoms of a failing one. Im getting my hands on a spark tester. I like you, am waiting on some more replies. I ruled out its not a fuel delivery problem.
 
Yesterday i just had it on the muffs. But i just remember something when i pumped the bulb up i herd air coming in the vicinity of the fuel pump, which is the VRO pump. My question is if it is the fuel pump diaphragm will the motor still start up? I dont remember if there was oil in the water at the dock. It ran great for the last several weeks. I use it quite often. Should i try giving it the key and see iff she will stay running?
 
I just jumped in here.... 143 psi compression on all 3 cylinders is good. I may have overlooked but I see no mention of a spark test....... With "all" spark plugs removed, at cranking speed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?........... Do the above test... important!

Now, you've mentioned the stator, questioning it a few times. The stator incorporates three (3) separate coils, all larger than the accompanied battery charging coils within that component. Those three coils, spaced evenly, provide approximately 300ac volts to the powerpack capacitor, needed to engage the powerpack.

Look under the flywheel and inspect the stator as closely as possible. If you see a sticky looking substance dripping down from it, upon the powerhead area, that indicates that the stator has overheated, resulting in at least one of those larger coils to engage a meltdown process. If this is the case, replace the stator regardless of what reading you may get from it. A stator in that condition results in a AC voltage drop to the pack which in turn results in weak, erratic, and eventually no ignition.

NOTE: Also... if you have suddenly encountered tachometer problems, explain.
 
joereeves said:
I just jumped in here.... 143 psi compression on all 3 cylinders is good. I may have overlooked but I see no mention of a spark test....... With "all" spark plugs removed, at cranking speed, the spark should jump a 7/16" gap with a strong blue lightning like flame... a real SNAP! Does it?........... Do the above test... important!

Now, you've mentioned the stator, questioning it a few times. The stator incorporates three (3) separate coils, all larger than the accompanied battery charging coils within that component. Those three coils, spaced evenly, provide approximately 300ac volts to the powerpack capacitor, needed to engage the powerpack.

Look under the flywheel and inspect the stator as closely as possible. If you see a sticky looking substance dripping down from it, upon the powerhead area, that indicates that the stator has overheated, resulting in at least one of those larger coils to engage a meltdown process. If this is the case, replace the stator regardless of what reading you may get from it. A stator in that condition results in a AC voltage drop to the pack which in turn results in weak, erratic, and eventually no ignition.

NOTE: Also... if you have suddenly encountered tachometer problems, explain.
Click to expand...

2x on this.

Add this to your testing, pull the pulse line off the VRO and squeeze the primer, NO FUEL SHOULD COME OUT OF THE PULSE PORT ON THE VRO PUMP.
 
Thanks Joe. Yes my tach has been going eratic, but there is a loose wite on it and sometimes makes it go nuts. If i whack it with my fist, at times, it goes from 5000 down to 1000 where i am at idle. I felt under the console and found this at the time so been ignoring the erratic behavior.
 
Asport-16 said:
Thanks Joe. Yes my tachometer has been going erratic, but there is a loose wire on it and sometimes makes it go nuts. If i whack it with my fist, at times, it goes from 5000 down to 1000 where i am at idle. I felt under the console and found this at the time so been ignoring the erratic behavior.
Click to expand...

Understood... However, it would be a good idea to correct that loose tachometer wire, if indeed that is the cause of its erratic behavior. My reasoning is that, when all is well with the circuitry and the tachometer itself is okay... to have the tachometer suddenly go berserk (so to speak)... It has always been due to a regulator/rectifier failure that causes a voltage backup to the stator which in turn results in a stator meltdown. A one thing leads to another failure type thing.

At the moment... your tachometer problem could indeed be the loose wire thing mentioned... OR... it could be a warning of a much more expensive failure. Correcting the loose wire problem if it exists... gets rid of the "OR".

At any rate... be sure to inspect that stator as mentioned.
 
How do the wires look heading up under the flywheel? Anything that moves when the throttle is moved, could be suspect as well.
 
Yes its i hope a simple fix with the tach, once i get it out. Idk the tack is tell tale with the stator. Im starting it up shortly with new plugs. A friend of mine told me that possibly my vro is out of wack and putting in to much oil, so much that the fuel going in cant even it out. If my diaphragm side of the vro went with the fuel pump side, would it still start right up? Ill also test the battery with my multi when its running to see if the battery is charging might tell me something. Im also going to check my fuel primer selanoid to see if thats working correctly, if it is ill try to keep it going while running with the key. Seems as though she is over whelmed with oil. Ill give you an update as soon as i get some results. Thanks for the feedback guys
 
It sucks being a rookie, we jump the gun, thats what i did. Thanks to Joe Reeves, Timguy and Dockside Marine Services for helping me. With my diagnosis of pushing in the primer it had to be fuel related. So while i fixed the wire on my tach, it bothered me, figured ill pull the carbs and retrace my fuel lines and clamps, while i had the carbs off, i went into the #1 the high speed orifice was clogged with what looked like tiny pieces of rubber Obviously from my old lines or maybe the new stuff i just put in. After i primed her it ran smoothly at idle, no cutting out and no more eracted tach. Yeah i feel foolish getting ready to buy a new stator or fuel pumpi found out its important to go down every avenue first, before you hit the panic button. Thanks again .
 
Asport-16 said:
...But i just remember something when i pumped the bulb up i herd air coming in the vicinity of the fuel pump, which is the VRO pump. My question is if it is the fuel pump diaphragm will the motor still start up?....
Click to expand...
Do you see fuel leaking anywhere. You should hear no air around the fuel pump. you will hear fuel 'sloshing' as it fills the carb bowls, but that should stop after the float needles get seated.

If you squeeze the bulb after the needles seat, do you still hear air or see fuel flowing? If so then you probably do have a bad diaphragm in the pump.

Yes, the engine will start even with a bad diaphragm. When you fill the float bowls the carbs have all the fuel they need to aspirate the liquid and run the engine.
 
Yes it did that on the water, something similar to this happened some time ago and it ended up being the bulb, which I replaced, thought it happened again so i put on a new one. I didnt hear anything and didn’t see fuel leaking, the bulb stays rock hard, noticed the mixture is carbon rich but thats just the carb adjustment i havnt gotten to yet, ill close that gap in a day or two. It probably could use a new pump anyway, its 20 yrs old.
 
Actually of all the fuel lines I replaced theres just 3 i havnt done. The return for oil line going into the vro and that 1 fuel line. Its all wedged in there pretty good, ive been trying to look for the pulse limiter, i dont know if it’s mounted to the hose or the block, on my 98 model. Im planing on getting a new pump along with steering cable and helm, remote control boxand new shift and throttle cable. Ive only had the boat for 7 months. It was garage kept all of its life but nothing outside of regular maintenance was done on it. It has a great hull in prime shape. I think its worth putting the money into it. That test for the pulse limiter after i do it, will the warning buzzer go off after I install it back? All alarms on this boat work.
 
If fuel comes out the pulse port.....its "B O A T". Oh, it can't possibly have anything to do with saving 50 cents a gallon on ethanol......can it?
 
Wouldn’t even think of it. No ethanol is going in my boat. SW Florida is a boaters paradise. Dont have to go far at all, for the only gas, one should put into their boat. Im lucky there, good location
 
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