1976 Johnson 70 hp stator test

[Coltrickle]

I have a 1976 Johnson 70 hp that I have been nearly all the way through.. I have a lot to tell so please bare with me.. Rebuilt all 3 carbs several times. Disassembled exhaust plates and head. Lapped/resurfaced all plates, replaced all gaskets, new t-stat, water pump Assy and all.. I have 124 psi compression on top 2 cylinders and 120 psi on the bottom. I can not get this motor to idle longer than about a minute and it will slowly die.. Then act as if it's flooded.. I pull the plugs and they are wet with fuel.. If I try to take off it is sluggish and will sometimes bog down.. But once I get the boat planed out it runs perfect.. You can back off the throttle and get back in it and it will tach right back up wide open.. But if you slow enough to come off plane you start all over.. If I run wide open for 5-10 minutes it will usually die not long after I come to idle speed.. So this is where I am now.. The trigger and stator both pass ohms check however the coils will only ohm on the primary circuit from the wire that connects to the power pack to the wire out of the coil to ground.. They will not ohm on the secondary circuit that is from the spark plug wire to the wire that connects to the power pack which is what the coil trouble shooting guide states it should be able to do.. Also I am only getting 93-97 volts on the brown and brown/orange wire coming out of the stator.. Cdi states it should be around 150v a/c.. So the question is.. Is it possible that all 3 coils are bad and would it still run if they were?? I may be ignorant to the test instructions but I am almost certain I am performing it correctly. Also should the stator put out the 150 at idle or at wot. I only get the mid 90's at idle and if I rev it up on muffs it drops into the lower 80's?? And would this possibly have an effect on the symptoms I described!! I know it's a lot to take in but if anyone has any advice it is greatly appreciated!! Thanks in advance for your help.

 

[wrench 3]

Your symptoms sound like it's still over fueling. Have you done any work on the fuel pump?

 

[Turn4fun]

Man this sounds an awful lot like the way mine was acting. After replacing all of the coils and the powerpack, rebuilding all of the carbs and testing everything I could, I finally gave up and took it to the dealer for diagnosis. Turns out the lower crank seal was shot. You might check into it. See my thread here

http://forums.iboats.com/forum/engi...boards/10138215-1976-evinrude-70-hp-need-help

 

[Coltrickle]

wrench 3 Turn4fun I have replaced the fuel pump with a new one. Sorry I forgot to mention that.. I have heard about the crank seals but do not know how I could determine that myself.. I I guess it may be time to bite the bullet and pay the man!! Trying to not go that route.. I appreciate all of your input.. Thanks for the thread.. I will check the fuel and see if I can determine anything else.. I know these carbs have no adjustments so they work or don't.. I am at wits end!!

 

[pontiacfieroguy]

I have very little boat experience but I like tinkering on 2 stroke motorized bikes and you might try bending the float arms down a tad if you are flooding and can't adjust the idle or high-speed jets.

 

[F_R]

Lets back up a bit. Will it start ok? Will it produce a spark across a 7/16" sharp pointed gap at cranking speed? If it will, chances are there is nothing wrong with the ignition system. But I am a bit curious about the lack of a resistance reading through the secondary. Do you have your meter set to a suitable scale to read the higher resistance? How about the spark plug boots & the spring inside? They may not be making contact with the wire core.

You say it acts like it is flooding or running too rich at idle. Might be.

 

[F_R]

Correct idle orifices? Or possibly somebody drilled them oversize? Or buggered them up with wires, and stuff? I believe they should be #30, that is .030" diameter.

 

[Coltrickle]

F_R yes sir it will usually start up great the first time but will die idling after a minute or so after the fast idle lever is lowered and is not as fast to fire off the next go around. If I launch my boat and start the engine it will run fine while tied to the pier after warming a minute or so I can lower the high idle lever and before I can get to my truck to go park it the engine will be near dead or already dead.. The only reason I didn't consider the carbs to be rich was because the motor used to sneeze and I was told it was to lean.. But it no longer does that.. Also once I run it wot and come back off to idle it dies pretty quick.. It will also jump a gap over 1/2" bright blue spark. my meter is a fluke T5-1000 it has a 1k ohm setting.. It can read the stator ohms and they are around 635 from the brown to brown/orange which is within spec according to cdi. And the 3 white/black trigger wires individually to the lone black/white are around 18ohms which is within the 10-20 range given.. The primary circuit of the coils are down to 2 ohms each.. But no secondary readings.. I took the coils off the mounts and tried them unbolted and all wires disconnected just to be 100%.. But no reading from the plug wire to the wire that connects to the power pack.. And also no reading from the plug wire to the primary ground.. I checked that one just for grins.. I have looked at all the jets and you are correct sir, the idle jets are .030". It is stamped on them however I have not verified the actual diameter of the orifice.. Would as little as 2-3 thousandths make it flood out?? Just asking to see how sensitive they are to engine performance.. I can remove them from the carbs and take them to work and dim. check them or i could probably order 3 new ones relatively cheap.. thank you for your replies sir!!

 

[F_R]

Don't know what to say about the coils. It would seem odd that they are all bad, but I suppose stuff happens. But back to the spark issue, it sounds OK. At least for now. Those coils might fail in the future. Question is how far in the future.

You mention the fast idle lever. How slow is it idling when all the way down? Perhaps too slow?? Are the 3 carbs completely closed at slow idle? (Should be).

 

[Coltrickle]

The carbs are completely closed at slow idle.. I have adjusted the slow idle up a little but if I raise it to high the engine won't start after it is warmed up.. I have attempted to adjust this many times.. In a barrel, in the lake and it seems that when I think it's right the next time I crank it will either not start or hits then dies right back..

 

[oldboat1]

To check for a bad lower crankshaft seal, pull the l.u. and check for fuel/oil up around the top of the driveshaft, at the splines.

 

[Coltrickle]

oldboat1 thank you.. Sorry for the long wait to reply. I had to stop working on it for a while. The seal is good. I rebuilt all 3 carbs with all new parts and it will idle as long as I want now. It still has a miss when going through the throttle. About 1/3-1/2 way through the throttle it has a dead spot. If i ease through it I can get to wot but if I hammer down on it it just Boggs and dies out.. Any thoughts? Thanks

 

[jakedaawg]

oldboat1 thank you.. Sorry for the long wait to reply. I had to stop working on it for a while. The seal is good. I rebuilt all 3 carbs with all new parts and it will idle as long as I want now. It still has a miss when going through the throttle. About 1/3-1/2 way through the throttle it has a dead spot. If i ease through it I can get to wot but if I hammer down on it it just Boggs and dies out.. Any thoughts? Thanks

During all the carb rebuilding did you replace fuel lines from pump to carbs? Are any of the bends in the lines a little too tight causing a restriction? Sounds like you maybe a little clogged in the off-idle and transition circuits of one of the carbs.

 

[Coltrickle]

All lines have been replaced. They have as much room as I could give them to not kink.. It's pretty tight in there where the fuel line has to fit.. It's just odd.. When I first got it the dead spot was right after you started through the throttle just off of idle it would die. But if you hammered down off the start it would take off like a scalded dog.. Now it's where the boat is about to start the plane process and you have to ease through the throttle until full plane then you can hammer down to wot. If i don't ease through the dead spot or if I just hammer down it Boggs down and dies..

 

[wrench 3]

I just reread the whole thread and can't find any mention of the synchronization being checked?

 

[Coltrickle]

I have attempted to perform this in the past but I couldn't get it to where it was acting right. I marked all settings prior to adjustment and put them back after I could not perform the link and sync as they say.

 

[jakedaawg]

Sure sounds like you have a needle not seating or a heavy or mis-adjusted float. Here is what to check:

With the air silencer cover off and engine trimed down but.not all the way down. You want a slight tilt so that fuel coming out of carbs will run forward and out the front. hold the bulb with the arrow pointing upwards. Squeeze bulb.till firm. Once firm keep applying pressure to bulb. You're not squeezing super hard but you should be squeezing. I bet the bulb will continue to depress. Give it a good 30 sec to a minute. Eventually you will see fuel come out of the the thrhroat of the carb. Note which carb. Address float, needle and seat of that carb.

Easy test, only take 3 minutes. I have done 100's of carbs and every once in a great while it just happens. You miss some little thing and have the exact problem you are getting.

 

[oldboat1]

good info., Jake....

 

[Coltrickle]

Thanks for the info.. I will try out first chance I get!!

 

[Coltrickle]

Ok. I tried the test today and noticed the that the bulb did continue to depress slowly and I can see a slight amount of fuel around the base of the main jet in the throat of the top two carbs. So what do I do next.. All floats needles and seats are new and I have adjusted the floats per instructions. Do I drop the float level a hair so the I don't have as much fuel in the bowl? Thanks