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Erratic timing poor idle

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weshebron

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I have a 90 hp evinrude model is E90TLCDC and i have been having some issues regarding timing-idling. So i set full advance at 28 deg @ 5000 rpm engine seems to be running pretty well at high rpm. The problem is at idle and at start. The timing at idle is moving back and forth about 3-4 deg was wondering if anyone has any insight. Will not start if it has been sitting unless put in neutral and given throttle. Rebuilt carbs and replaced all jets and have new plugs and wires. Will not idle without the cam follower slightly touching the cam and i know this can't be right being that the manual a purchased says that the cam should not be touching the follower in neutral. I was going to attempt to do the ignition trouble shooting procedures but do not have a dva adapter. Also does anyone know the a modern equivalent for battery type? Any help would be greatly appreciated.
 
I just checked for play and doesn't seems to have an excess amount of play. Is there supposed to be no play at all? I'd say there's no more the a 1/16" play.
 
Timing on these motors does not go out of adjustment !-------------I would start with a compression test on this motor.-They have a history of broken piston rings once they have some hrs on them.
 
Ok so I've read in the manual how to go about checking compression and understand that main focus is variance between them but is there a idle pressure or tolerance for actual pressure
 
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Ok so I've read in the manual how to go about checking compression and understand that main focus is variance between them but is there a ideal pressure or tolerance for actual pressure
 
Many times folks will ask for the preferred readings.---------Gauges and techniques vary.----Do yourself a favour and post your values here.
 
Pull the plugs and with a fully charged battery and a cold motor check all the cylinders three times 1-4 1-4 1-4 and take the high number for each cylinder. Then post the results here.
 
Get a open air spark gap tester or make one and all four plug wires should jump a open air gap of at least 7/16 inch brite blue snap. Compression looks good for a 40 yr old motor.
 
Use the search...this same issue has been covered tons of times on this site alone.

Clue quickstart timing, and throttle body cleaning.
 
ok so #1 and #3 jumping 7/16" gap bright blue.
however #2 & #4 are not. #2 barely visible at 1/8" and #4 at about a 1/4" both of which appear to be more of an orange/yellow color.
 
For the best diagnostic from here a DVA adaptor will nail it down. Have you gone through and cleaned all the wire connectors with electrical cleaner and put back together with dielectric grease. Sand all the grounds metal to metal including components that use bolts for a chassis ground. CDI electronics has good troubleshooting procedures. Just click on the CDI parts and click on installation instructions.
 
Thank you! I really appreciate everyones help. I will post results when i obtain an DVA adapter. If anyone knows if there any literature on how to use one or anywhere i could get one it would be a big help. The manual i got just speaks of the omc neon tester
 
You sound pretty sharp all it is is a capacitor, resistor and diode for measuring peak pulse voltage. The pulses from the stator or trigger charge the capacitor so you can read the voltage with a VOM. Find the part here stator, PP, ignition coil or timer base (trigger) and follow the instructions. Swap the two coils with the ones not working and try again if it follows the coils the coils are bad if it stays the same the coils are all good. Then swap the powerpacks if it stays the same the both powerpacks are good and you need the DVA to test the outputs of the stator and timer base. Sometimes you get lucky and can isolate the problem with a ohm meter but not allways.
 
Ok sounds great. I also found a pretty cool "DIY" DVA adapter but unfortunately radio shack did not have the [FONT=Arial, Helvetica, sans-serif]Capacitor required, bummer. That would have been a cheap alternative. But it does make perfect sense to try and switch the coils and powerpacks to try and see if they are the problem. [/FONT]
 
One more question if anyone could assist with. The rectifier literally caught on fire last year when i first got the motor and started the boat rebuild. The local marine dealer where i purchased the rectifier said that my current battery was fine when asking about the enclosed cdi info about maintenance free batteries would void the warranty. After reading some post about the rectifier possibly causing other problems with the electrical system of the motor. I then wonder if the deep cycle battery I'm using is causing these issues. I was not aware that the deep cycle/starting maintenance free battery demanded more from the rectifier than it could produce. So what battery should i actually be using. I'm kind of confused about about this. Any help is appreciated.
 
Finding the faulty part is part of it next is to try and determine why it went bad. Normally due to overcharging be a bad battery or the wrong battery. Allways use a lead acid (old style) battery they can handle the higher voltages produced at high rpms. If you see tar like goo dripping off the stator it is on its way out. It is recommended you replace the reg/rect when you replace a stator.
http://www.marineengine.com/newparts/part_details.php?pnum=CDI193-3408
It still says not to use a maintenance free battery.
 
Any auto part store should have one. If you use a electric trolling motor it is probably best to just run it on a separate battery and charge it when you get home. Your engine is not producing enough amps to charge it anyways with alot of use. One trick is to run a high amp appliance like a 12v ice chest while the engine is running to use up the high voltages produced at high rpms. Maintenance free batteries store energy alot more efficient, adding a volt meter is also recommended so you can monitor battery voltage real time so you dont burn up expensive ignition/charging parts.
 
So i went to pasco today and this is the battery i walked out with. http://www.pascobattery.com/marine/...recision-group-27-800-cca-1000-mca-12v-marine The guy that worked there said that this is what i needed but i honestly have no idea as to what this guy was saying. It is a lead acid marine cranking battery and you can add water to it so i guess thats better than the deep cycle Walmart special i've been using. I have a charger that has 3a and 15a setting does anyone know which setting i should be using?
 
Allways use a slow charge to extend the service life of the battery. When not is use over long periods pull the battery out and use a trickle charge and keep it up off the concrete. What did you find out with the ignition? Did the problem follow the powerpack? One of those battery disconnect switches work good for disconnecting the battery from the system between uses never charge the battery when connected to the motor.
 
thank you so much for that info. I did not get to check to see if the problem followed due being dependent upon the girlfriend cranking while i watch the gap tester i got it all set up last night but by the time i got home today she was already off shopping with her friends "dammit" so i went to grab a battery. Hopefully tomorrow. I will definitely post the results as soon as i get done. Once again all the help is greatly appreciated and thanks everyone for being patient with my lack of knowledge.
 
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