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hard start 1972 125 hp johnson

4

48tony

Regular Contributor
this engine does not start correctly unless I manually prime the carbs with spray bottle with gas.when it starts it runs good for the most part.the choke flaps are adjusted to close evenly and tightly to the carb body when the switch is ingaged.i took the thermo choke wires off and wired the dual stage silinoid directly per bulition info. both wires connected on the terminal bar.comprestion test read 140 on all 4 holes.even after it has run and up to temp and shut it off it soe times starts with a quick turn of the key but then there are times when it will not start.i have rebuilt the carbs and cleaned real good took out the welch plugs ran thin wire with 120 lbs of comp air in the small fuel passages.this hard start is driving me crazy.all new ele coil and power pack by cdi .I was thinking the fuel pump may be the culprit but it runs good at wide open and out off the hole with no sluggish sysmptoms.to be sure I changed it out with a good one and it is doing the same.someone told me the rings could be worn not getting the sucktion in the crankcase but with the reading of 140 that is real good for a 40 + year old engine.what else could be causeing this.
 
I'd focus on the choke and throttle linkage adjustments. You are pushing the red fast idle lever down on the remote control,.....aren't you?
 
Are you sure both coils in the two stage choke solenoid are good? One wire/coil pulls the plunger down part way. Both wires/coils at the same time combine to slam it down tight shut for cold startup. Just one stage won't get it. If you rewired it correctly, both wires/coils should be doing that.
 
Possibly this is a problem..............

(Voltage Drop To Battery Capacitance Discharge)
( Pulsepack When Electric Starter Is Engaged)
(J. Reeves)

On the older Battery Capacitance Discharge ignition systems (1968-1972), the electric starter reaches a point, even with a top notch battery, whereas the starter will draw excess voltage/current/whatever which results in a voltage drop to the pulsepack. The cure is to purchase a diode which is capable of handling 12 volts and installing it between the starter terminal of the starter solenoid (NOT the battery cable terminal) and the wiring terminal that supplies voltage to the pulsepack.

The diode must be installed so that the current flows from the starter terminal of the solenoid to the pulsepack... NOT vice versa. When that diode is installed in this manner, when the key is turned to the start position, the voltage that is applied to the starter is also applied directly to the pulsepack via the diode effectively eliminating the voltage drop and energizing the pulsepack with the required voltage needed for its proper operation.
 
my control box has the lift to cold start leveer on it it was for a 1970 60 electric hydro .the control box that came with the 1972 does have the red lever that pushes down for cold start but the 1970 60 box seemed to be in better shape so using that one instead every thing is the same .but yes when I cold start the 125 hp I lift it up and and I have the timing advanced idle set at 2300 rpm and seeing I diconected the heat thermo wires to the 2 stage choke silonoid when the motor does start I feather the choke toggle a few times then I disengage the advance after a couple of minutes.and she idles pretty good at 1000 rpm on the muffs in the water it t about 800 rpm.i have the 2 wires off the choke silinoid hooked up together on the same terminal screw as the bullition states.joe I notice some thing the other day I have 2 good deep cycle batteries hooked up with a make before brake isolater switch it seems I need to put the switch in the all position in order to crank it over if it is on the 1or 2 setting the moter turns over sounding like the battery is dead .when I put the switch in the all setting it cranks over good.so I belive the diode is something I need. or could something elese be the culprit the starter is brand new along with a new starter silinoid
 
OK, good explanation of what you have done so far. Sounds like you have the choke solenoid wired correctly, but have you verified that both windings are good?

The fact that it takes two batteries to crank it doesn't sound right. Something is wrong there. Time to do some voltage drop tests on the whole starter circuit. You sound like you know what you are doing, so I assume you know what voltage drop tests are.

The diode may help, but if it does, it might merely be covering up a voltage problem. Time for tests.
 
48tony said:
.Joe I notice some thing the other day I have 2 good deep cycle batteries hooked up with a make before brake isolator switch it seems I need to put the switch in the all position in order to crank it over if it is on the 1 or 2 setting the motor turns over sounding like the battery is dead .when I put the switch in the all setting it cranks over good.so I believe the diode is something I need. or could something else be the culprit the starter is brand new along with a new starter solenoid
Click to expand...

Your explanation of the above indicates that either one battery is faulty "OR" a cable is either loose, tight but dirty at its terminals, or a cable is corroded internally.

However, even when all is well, the diode would be helpful with that Battery Capacitance Discharge ignition system.
 
thank you guyies for the fast feedback.first off I cheked the 2 stage choke silinoid and it does work I took one wire off at a time and flipped the toggle and with one wire it activates the plunger with both you can see and hear the difference. it slams it shut with both hooked up.as for the battery problem I will go take off all my cables and clean them to a shine conection and hope that does the trick if not I will need some help on some voltage drop test electrical testing is not something I am up to speed with.but with your feedback I think I can find the problem. thanks tony
 
ok first off I went out yesterday and cleaned every +and - cable on the motor hopeing it was the cause of the starter cranking over slowly I even took the double battery switch apart and shined all the leads off nice.when I went to start it with the switch set on 1 it sounds like I got a dead battery then set it to 2 same thing set it to all and it sounds fine the starter cranks the motor just fine.i let it run a while then shut it off set the switch to 1 and it cranks fine and same on the 2 setting on the switch.why would warming up the motor have anything to do with it .racer the clipper box is no longer in the circuit.i did put on a after market voltage reg - recterfier by cdi inc as you no these older johnsons never had a regulater my volt gage at times would read 16+ volts I then put this new reg- rec and the gage reads normal at 13+ volts .dident the clipper box only stop high spike volts from harming the power pack it does not regulate volts in the ingnition were cdi just came out with this new retro fit regulater the guy at cdi told me that they cannot keep up with the orders on this part.he said that they had been working on making this part for sometime. I have read a lot of post regarding these older moters reading hi volts.my first fix was hooking up a set of flood lights on the boat and when buzzing around the lake and the volt reading got up in the 16+ volts a simple flip of a toggle would drop the volts.but to me that was not a real fix and parts on these ignitions are big pennies as you no.well I think I will need to do some testing on the motor.I plan on taking the control box apart today and clean the key switch wires and see what that does inorder to fix the dragging starter problem.can I do a load test on my battryies with a 12 volt and ohms tester.i need some guidance when it comes to electrical.
 
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