1971 johnson 100hp no idle.

[Justinpereira]

Hi I got the 100esl71a Johnsonout outboard.
I've pretty much been over every component by using this sites forum and tests on internet.
I've used this motor this year many times like 3 times a week and almost every weekend with no problems. Started perfect with barely a rotation of the flywheel,once warm everytime.suddenly it started hesitating at almost full throttle,to a point where it kinda changed.now I can start it with the fast idle lever up and fires everytime. But as I lower the idle to normal it quits. On the lake I got stranded and the only way back was to start it and throw it in forward and giver.it runs perfectly at half to full throttle until the tank would run dry but the minute I get close down to idle speed it it dies instantly. This has an amplifier is a dual points system .the carbs have been rebuilt and cleaned, the ignition switch is new ,sparkplugs,amplifierbox looks replaced and coil. This is a v4 with one coil only. New rectifier aswell. Stator looks clean and flywheel magnets. So far what I did notice was the blocking diode in the shifter assembly was melted looking and touching the metal box . Fixed that .and made sure terminal screw red had same as battery volts aswell as the purple wire.

Now what I notice is that with my muilti meter leads on battery positiveand negative its says normal 12.5 + volts but while running the numbers on the meter go crazy like I can't even get a reading. On dc 20 setting. When I disconnectedpurple and green wire from terminal strip . The voltage was normal reading 12.5-15v. While running.
I tested stator on ac setting and cranked and got the same kind of crazy numbers. I un hooked the stator wires from terminal strip and it fired up not good but much better because I didn't have to put the fast idle lever up.
I set the points on my motor one was at .014 other at .012.I set them both on highest part of cam to .010 like timer base engravingsays.

Hopefully someone can help I feel like theres nohing I can do anymore.
Also can someone elaborate on the anti reverse spring. Could this be my issue.
Idle speed seems to be my issue but why? Thanks so much

 

[emdsapmgr]

When later models start having idle problems, the first thing to look at is the idle jets. They do plug up with dirt, debris. Your engine does not have idle jets, but rather the idle screw. In your case you may have some debris wedged between the idle screw tip and the body of the carb. If your engine has any old hoses (pre-ethanol hoses) these will break down when flowing today's fuels and you can get bits of the black hose throughout the carb and it's passages. So, clean the carbs and make sure all your hoses are rated to handle today's fuels. That includes your fuel tank hose and all hoses under the cowling. Keep in mind when the carbs are set to idle, the butterflys should be completely closed. Air flows only thru the small hole in the butterflys. Fuel only flows thru the idle passages. Once you crack the throttle even a little (open the butterflys) the carb will draw fuel from the high speed jets. Might as well remove the high speed jets and visually inspect them also.
The rectifier will re-charge the battery. When first started, the battery voltage will read somewhere around 12.5 volts. As you run the engine, the voltage will start to come up as the rectifier starts to replenish the battery voltage. It can get up to 16 volts as the battery charges. This is normal, as these older units do not have voltage regulators. If you get concerned about cooking the battery, play the radio. Keep watch thru the summer on the water level in the battery.

 

[boobie]

Do a compression test on it and get back to us.

 

[Justinpereira]

Hey guys, so I did the compression check 140 evenly. That's a relief. Lol and I set the float level to the base of carbs and the neeedle valve show NO wear ring around the tip. The high speed tubes are clean and clear also. Went back and cleaned and soak the low speed orfices in the carb , and removed needle valve (4) and cleaned and shot 120psi threw it . Made sure I felt and seen every little hole leaks out the carb cleaner. Put it back together and 5/8th turn out from bottom.I did notice that the little gasket inserts that seals the needle two are not sealing and the needle back out very easily. Also one needle seems a little bent while threading in. I set up the timing and carb adjustments because it didn't seem right. Is it possible that even with set points to SPEC that a point may be bad. Like the contacts looked clean and I sanded them lightly in a previousattempt to get it to idle. Turning flywheel by hand and doing a. continuity test seem like the points were good. Now with bringing back the idle screw to a more centered position in stead of maxed out, I then notice the throttlecam and carb thottle wasn far apart so I move that small brass colored arm . Now it harder to start unless the fast start lever is maxed. Before it would come down half and then suddenly quit. Could one point be faulty and mess up the duration between both points . The points don't have a condenser and the points are offset.
And I really appreciatethe help thank you

 

[Justinpereira]

I also replaced all fuel hoses. And removed anti reverse spring because I didn't notice it touching the points block when trying to return the level to idle. I will be replacing it. But removed it in trial and error process. Also when I take the bok/ white trigger wire and strike it to the block the the coil fires. And when cranking the spark at plugs. And I got it to somewhat idle lower for a bit but its surely seems to be a problem with the timer base advancing or points.maybe amp box.?