Bad Synch & Link Adjustments 1990 70hp

I'm trying to finish my friend's 1990 70hp 3 cylinder so he can sell the boat, and I have run into a problem with the Idle Speed and Synch and Link adjustments, here it is:

On the water, I had to set the idle speed at the maximum the idle speed adjustment screw would go in, in order to get the RPMs the engine needed to not keep turning off at idle when starting in cold. To be more detailed, every time when I would turn off the engine to fish for say 15 minutes, I would have to rev it up, accelerating in neutral to get the engine to start, it would not start at the idle speed. With the idle adjustment screw all the way, it worked better, but still not really good like I've experienced in the other engines that I have had or worked on in the last 7 years. Those engines in the same situation, turned on just by touching the key without any acceleration in neutral, just in idle speed.

After I set the Idle Speed Screw to the maximum, the engine idle speed in neutral was 1275 to 1300+ rpm on my hand held tach, but in gear it was around 800+, which worked fine. Later when I went to set the Throttle Cam Mark (B) to the Cam Follower (C) they would not align until I set the Throttle Cam Locknut (E) to the maximum it would screw into the left. Then in order to get the Wide Open Throttle, I had to set the Wide Open Stop Screw (F) all the way out so the stop was actually the body of the engine, not the screw. In other words, In order to get the Cam Mark to align, I had to set the Idle Stop Screw to the maximum it will go in, the Wide Open Stop to the Maximum it will go out, and the throttle cam follower screw to the maximum it will go back to the left, everything is maxed out!

I had previously set the carburetor idle mixture needles at one turn out, which improved the rpms. I had adjusted the carb throttle plate. The engine runs great at high speed.

I say it all the time.----Many folks pick on the carburetors for some reason.-----Any other trouble shooting done ??

!st thing to check..... Compression, all spark plugs removed. What is the psi reading of each individual cylinder?

2nd thing to check... Spark, all spark plugs removed. The spark at cranking speed must jump a 7/16" gap with a strong blue lightning like flame... a real SNAP!

The need to have the idle screw set all the way in indicates that something more is wrong with the engine than minor adjustments.... usually why one wants to sell the rig.

Hopefully you haven't changed the distance between the vertical throttle arm and the cam... that would change the idle timing and through everything out of adjustment.

joereeves said:

Hopefully you haven't changed the distance between the vertical throttle arm and the cam... that would change the idle timing and through everything out of adjustment.

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Do you mean loosening the locknut and adjusting the thumbscrew on the Throttle Cam? If so, I already did mess with it.

joereeves said:

!st thing to check..... Compression, all spark plugs removed. What is the psi reading of each individual cylinder?

2nd thing to check... Spark, all spark plugs removed. The spark at cranking speed must jump a 7/16" gap with a strong blue lightning like flame... a real SNAP!

Click to expand...

Sounds likely the ignition needs some work.

racerone said:

Sounds likely the ignition needs some work.

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What's next doctor? Should I follow what the manual says for Ignition Output Tests? or do you have short cuts? I tested the spark with three different testers and the last two I grounded directly to the battery ground, so there's no problem with the testers.

It has been proven time and time again that folks have trouble with electrical things and tools to test electrical things.-----Follow your factory manual or the ----cdielectronics-----Trouble shooting guide.-----Those will help you inspect and understand how things work.

The engine must crank over at least 300 rpms in order for the stator (under the flywheel) to produce approximately 300AC volts to the power-pack's capacitor, required to energize the powerpack. A slow cranking engine will result in weak, erratic, or no spark.

If the engine's cranking over fast, and the spark will not jump a 7/16" gap, take a good look at the stator under the flywheel. If there's a sticky looking substance dripping out of it down on the timer base and powerhead area... that would result in a voltage drop to the powerpack... in which case the stator would need replacing.

Tinkering with that nut and the distance between the vertical throttle arm and the cam has screwed up the IDLE TIMING. You'll need to reset that as oer your service manual..... spark plugs removed, timing light hooked up to the top (#1) cylinder plug wire, the idle timing (whatever your manual states) should align (flywheel mark to pointer) when the scribe mark of the cam aligns dead center with the throttle roller.

It turns over real good at least the 300 rpm's, specially since the spark plugs are off, the thing is flying! I can also test it again with twin batteries to double check, but I don't think it'll make a difference in spark.

It is very clean under the stator no sticky dripping​

In the Synch & Link instructions for this 1990 70hp engine it says to adjust the Throttle Cam "Loosen the throttle cam locknut...rotate the thumb wheel until the throttle cam and the cam follower just touch". Maybe you mean I adjusted it too far, like 3/8" of thread?​

Ignition Out Test in Evinrude manual:

Step 1 - With spark plugs on …. adjust tester gap to 1/2" and test. If tester shows no output (it does not even jump 7/16") go to Step 2

Step 2 - Stop Circuit Test - Disconnect 5 wire connector between stator and power pack and insert jump wires to four terminals to isolate/eliminate the stop circuit. (my stop circuit wire is connect with a removable connector because the original wire broke off. So I just left the 5 wire plug in place and disconnected the stop circuit wire. I tested it and n the spark did not jump the 3/16", it di jump the same as before, weak thin spark at 1/4".) If there is no spark (it does not jump the 7/16") go to Step 3 Charge Coil Test

Step 3 - Charge Coil Test - uses a special tester, How do I do it with a multimeter?

From there it goes to a Sensor Coil Test, an Ohmmeter Test, Power Pack Test, Running Output Test, all these steps necessary?

One of the features of outboard motors since the early 1970's is ignition timing that requires NO ADJUSTMENT.-----So like I say I am not sure why folks start tampering and using the " i think I will adjust this or that "---- and see if it runs any better.----Find the real problem !!

Temporarily disconnect the Black/Yellow wire (Kill Circuit) at the ignition switch, then retest the spark to see if that allows the spark to jump a 7/16" gap.

The synchronization/Link thing..... what the book is telling you is that when the scribe mark of the cam is dead center with the roller.... the idle timing listed in the manual should register on the flywheel (timing light). And if it doesn't, the distance between the vertical throttle arm and the cam has to be adjusted one way or the other.

The roller itself should be approximately 3/8" in diameter..... If it is only something like 1/8", the outer covering has broken away. In which case replace the roller.

The charge coil(s), three sealed within the stator. Check out the ohm reading as stated in the manual. If the ohms check out and since it is not leaking (melting down)... you could assume it is functional. Wires leading to the powerpack are normally Brown and Brown/Yellow but I don't have the wiring diagram in front of me.

racerone said:

One of the features of outboard motors since the early 1970's is ignition timing that requires NO ADJUSTMENT.-----So like I say I am not sure why folks start tampering and using the " i think I will adjust this or that "---- and see if it runs any better.----Find the real problem !!

Click to expand...

I followed step by step everything detailed in the manual to do the Synch and Link to get the engine to idle right in gear and the Throttle CAM mark to align with the cam follower. I do not understand what that has to do with ignition timing.

Re:Temporarily disconnect the Black/Yellow wire (Kill Circuit) at the ignition switch, then retest the spark to see if that allows the spark to jump a 7/16" gap.
(Like I explained above in red, I disconnected the black and yellow wire at the power pack and tested it, and the spark was still weak, the same)

Re: The synchronization/Link thing..... what the book is telling you is that when the scribe mark of the cam is dead center with the roller.... the idle timing listed in the manual should register on the flywheel (timing light). And if it doesn't, the distance between the vertical throttle arm and the cam has to be adjusted one way or the other.
[Do you mean - what the book is telling me is that when the scribe mark of the cam is dead center with the roller.... the engine idle speed RPM's listed in the manual (it says 725+- 25 rpm) should register on the flywheel (using a hand held tachometer). And if it doesn't, the distance between the vertical throttle arm and the cam has to be adjusted one way or the other?]

Re: The roller itself should be approximately 3/8" in diameter..... If it is only something like 1/8", the outer covering has broken away. In which case replace the roller.
(the roller looks good is not warn where it slides on the Throttle Cam, or anywhere)

The charge coil(s), three sealed within the stator. Check out the ohm reading as stated in the manual. If the ohms check out and since it is not leaking (melting down)... you could assume it is functional. Wires leading to the powerpack are normally Brown and Brown/Yellow but I don't have the wiring diagram in front of me.
(Will do and report back)

Klink said:

Re: The synchronization/Link thing..... what the book is telling you is that when the scribe mark of the cam is dead center with the roller.... the idle timing listed in the manual should register on the flywheel (timing light). And if it doesn't, the distance between the vertical throttle arm and the cam has to be adjusted one way or the other.
[Do you mean - what the book is telling me is that when the scribe mark of the cam is dead center with the roller.... the engine idle speed RPM's listed in the manual (it says 725+- 25 rpm) should register on the flywheel (using a hand held tachometer). And if it doesn't, the distance between the vertical throttle arm and the cam has to be adjusted one way or the other?]

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You are not looking for any specific rpm, nor will what you are looking for be found with a tachometer. You need to use a timing light to find the Idle Timing Mark which is normally quite low... something like 2,3, or 4 degrees.

joereeves said:

You are not looking for any specific rpm, nor will what you are looking for be found with a tachometer. You need to use a timing light to find the Idle Timing Mark which is normally quite low... something like 2,3, or 4 degrees.

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Nowhere can I find anything in the manual that mentions the timing mark degrees with a light.

joereeves said:

You are not looking for any specific rpm, nor will what you are looking for be found with a tachometer. You need to use a timing light to find the Idle Timing Mark which is normally quite low... something like 2,3, or 4 degrees.

Click to expand...

Klink said:

Nowhere can I find anything in the manual for my 1990 Evinrude 70hp 3 cylinder that mentions the timing mark degrees required, or having to test it with a with a timing light, or that the adjusting of the Throttle Cam thumbwheel affects the engine timing.
​

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P.S.- I did now find in the manual that some of the 1990 3 cylinder engines, the ones equipped with the double mark Throttle Cam Part number 394466, do have to have the Throttle Pickup adjusted to 1 degree BTDC, just like Joe Reeves described. For those engines you use the Section titled Method "A" Synch and Link Adjustments, which is different from mine.

My engine has a single mark Throttle Cam Part number 431707 and uses Method "B" Synch and Link Adjustments, which has no section at all which mentions the Throttle Pickup adjustment to X degree. My model does not need it.

How does your book explain how to adjust that thumb wheel/lock nut to obtain the correct distance between the vertical throttle arm and the cam?

Here is all it says about adjusting the thumbwheel on the Throttle Cam:

Back to the original problem:

...every time when I would turn off the engine to fish for say 15 minutes, I would have to rev it up, accelerating in neutral to get the engine to start, it would not start at the idle speed. With the idle adjustment screw all the way, it worked better, but still not really good like I've experienced in the other engines that I have had or worked on in the last 7 years. Those engines in the same situation, turned on just by touching the key without any acceleration in neutral, just in idle speed. ​

Click to expand...

On all cylinders we have good compression, but weak spark. That's likely why the engine has to be revd up to start it. Joe Reeves said to test the charge coil ohms:

The charge coil(s), three sealed within the stator. Check out the ohm reading as stated in the manual. If the ohms check out and since it is not leaking (melting down)... you could assume it is functional. Wires leading to the powerpack are normally Brown and Brown/Yellow but I don't have the wiring diagram in front of me.​

Click to expand...

QUESTION - In the manual all the charge coil tests just show a drawing of the stator off the engine, but I don't find anything that says to remove the stator from the engine. Do I have to remove the stator assembly from the engine to test it?

No, there is no seen to remove the stator as long as the wires are disconnected so that they do not give a false reading.

I followed the instructions in the manual for the ohmmeter test on the stator assembly (see below picture) and got 350 ohms on the first test, well below the required minimum of 480+- 25 ohms, and on the grounded test I got 32ohms on both A&B, which should have been 0.00, so it did not pass there either. I only disconnected the 5 wire connector that I was testing, is that correct or do I have to disconnect all the wires coming from the stator assembly?

Is that the final verdict, do I have to replace the Stator assembly?

I see no reason to disconnect the other wires as you have been following your manual.

However... Please wait for another fellow knowledgeable member to jump in here to look over and verify your findings/readings before putting out $$$ for a new stator.

From what you've said here, it sounds like the stator is failing... BUT... it is best to have more than just one member agree on this point, especially since it is not a $5.00 item.

I just real quickly skimmed through this long thread, and hate to get involved. I'm assuming A and B are the charge coil wires, brown & brown/yellow, whatever? If I'm assuming correctly, and your Ohm meter is calibrated correctly, it should show zero Ohms to ground. You say you are seeing 32 Ohms. That is totally unacceptable. Gotta be zero. Again assuming your procedure and hookup are correct. I'm not there to look.

EDIT: I think I spoke too soon. There should be NO connection between the charge coils and ground---that is an infinity reading. Zero Ohms would be a direct short to ground. What am I missing here? I'm tired, been pulling out a bunch of plants that took over.

Appreciate you jumping in here gator. The use of the term "zero" to me always coincided with nothing, no connection, zilch, etc... Thanks for the second opinion.